【Abstract】 what frightened every firefighter mostly is that he finds the air will be running out before his retreat. Though firefighters are trained rigorously and disciplined severely before assignment, it always possible that because of the complexity of fire scene, retreat later than the plan, evacuation route blocked, getting lost on the site, firefighters haven’t left the fire scene while the air in the respiration was used up. This paper is going to take a discussion on the emergency measures of dealing with respirator air exhaustion, and advance a proposal to equip firefighters with filter canisters which have express interface to mask. This research will provide useful protection when the firefighter is in the danger of exhaustion of the air in respirators.
【Keywords】respirator; exhaustion of the air; fire scene; emergency measure; emergency equipment

0 Preface
When a fire occurs, the combustion of combustible materials will produce a large amount of gas, heat and smoke, among which the smoke and gas are collectively called fire smoke, which is generally composed of a mixture of suspended solids, liquid particles and gases produced by combustion. The main components of flue gas are solid particles and toxic gases such as carbon monoxide, carbon dioxide, hydrogen sulfide, and hydrogen cyanide.
The smoke from the fire will spread the fire, affect the sight of people, cause high temperature burns and cause poisoning, and cause great harm to the human body. According to statistics, most of the deaths in the fire scene are caused by smoke inhalation. Therefore, for firefighters performing tasks on the fire scene, respirator is one of the most important equipment to protect personal safety.

1 Status of use of firefighters’ air breathing apparatus
1.1 Structural composition and working principle of air respirator
At present, in the process of fire fighting and rescue in our country, the main breathing apparatus equipped is positive pressure air breathing apparatus (referred to as air breathing apparatus). The composition of positive pressure air respirator is generally divided into: mask, air supply valve, gas cylinder, pressure reducer, back support respirator, the gas tank capacity is generally 6.8L, and the gas cylinder is an aluminum alloy liner carbon fiber wound composite gas cylinder” , It has the advantages of safety and stability, strong pressure resistance, light weight, comfortable wearing and stable performance. The high-pressure compressed air is stored in the bottle, and the working pressure is 30MPa. After the high-pressure air in the gas bottle is decompressed by the pressure reducer, it enters the medium pressure The airway is sent to the air supply valve, and the air supply valve is connected to the mask, and the medium pressure gas is decompressed to the pressure that the human body can breathe according to the user’s inhalation. The part of the mask for the user to breathe is used to cover the face and isolate toxic , Harmful gas enters the human respiratory system. There is an exhaust valve on the mask to discharge the gas exhaled by the user, and the inside of the mask maintains a positive pressure. The exhaust valve is a one-way valve, which can only exhale but not inhale to ensure the safety of the user. The back support is used to support the cylinder part and the pressure reducer part, and keep the whole set of positive pressure air respirator and the user well worn.
1.2 Use of air breathing apparatus
Before performing firefighting and rescue tasks, every firefighter needs to undergo strict respirator training, including adaptive training and breathing management training. Adaptive training is to let firefighters wear air respirator for daily subject training, so that firefighters are accustomed to using air respirator for breathing, accustomed to wearing air respirator to carry out offensive operations and safe evacuation, and through repeated training, find people and equipment. The best combination and make the body form a memory. Respiratory management training requires firefighters to avoid unnecessary physical exertion as much as possible to reduce oxygen consumption; respiratory management training also requires firefighters to keep calm in critical moments, maintain a lower limit of breathing, not blindly consume oxygen, and actively. Find the best way to deal with it.
The fire rescue team implements strict operational safety order control at the fire scene. Every firefighter who enters the fire scene is required to carefully check the reliability and air pressure of the air breathing apparatus. If the air pressure in the bottle does not meet the standard, it cannot be used. The safety officer will record the time when the firefighters enter the fire scene, and remind the firefighters to evacuate in time. For firefighters who cannot evacuate in time, the on-site headquarters should immediately organize emergency rescue. 2 Analysis of the reasons for the exhaustion of air breathing apparatus on the fire scene
Although firefighters have received professional and strict training, and the fire rescue team has strict management on the safe use of air respirators, the exhaustion of air respirators on fire cannot be prevented. The main reasons are as follows:
2.1 The use time of air respirator is short
According to the test of Du Xin and others of the former Armed Police College, the 6.8L air respirator can be used for an average of 50 minutes in normal walking (1.5m/s) when wearing a fire fighting suit and an initial pressure of 30 Mpa in a non-fire environment. Jogging can use an average of 22.1min (2.74m/s). The oxygen consumption of climbing stairs is 2.72 times that of walking on flat ground, and the oxygen consumption of descending stairs is 1.87 times that of walking on flat ground. In the fire environment, firefighters are highly stressed, the operational load is high, the human body is affected by high temperature, and physical energy consumption increases, and firefighters often need to climb and go down stairs, and the use time of air breathing apparatus will be further shortened. At the same time, there are obvious differences in the individual oxygen consumption rates among different people.
Due to the limited use time of air respirators, firefighters have a very short working time in the fire scene. The direction of travel, fire fighting and rescue, and evacuation must be very clear. The action is very decisive, and there is almost no room for error. Once there is a gap between the fire situation and the forecast , or a certain combat link encounters an emergency and is delayed, the firefighters will face the pressure of insufficient air supply of the air breathing apparatus, and every minute of delay may bring serious consequences.
2.2 The fire scene is complex and changeable
Fire-fighting and rescue is a high-risk post, and the environment of the fire scene is changing rapidly. With the development of society and economy, all kinds of new buildings and new technologies continue to emerge, high and low (high-rise buildings, underground buildings, large-scale complexes, petrochemical enterprises) fires increase, and new industrial and commercial building fires have large fire loads, large fire areas, There are many types of materials and high density of personnel. When firefighters attacked in close combat, they were often unable to evacuate as planned or the evacuation time exceeded expectations due to sudden changes in the fire situation and new risks and situations; the originally planned evacuation route was blocked due to local collapses, explosions or changes in the direction of fire spread; The large building area and complex structure may cause firefighters to lose their way in the fire scene, etc., which may cause the air in the respirator to be exhausted before the personnel are completely evacuated. 3 Emergency measures after the respirator air is exhausted
When the air in the respirator is about to run out, firefighters will be under great psychological pressure and must find a safe exit and leave the dangerous area in a short time. Once you can’t get out of the danger area in a short time, you will face the threat of suffocation. When it is found that the air in the respirator is about to run out, the following measures should generally be taken:
3.1 Remain calm and exercise strict breathing control When assessing that the remaining air volume is not enough to safely evacuate the fire, do everything possible.
May prolong the use time of residual gas. Firefighters should control their emotions, keep calm, stay away from high temperature and danger as much as possible, strictly control their breathing, and avoid unnecessary air consumption. Any impulsive and blind movement will speed up the consumption of oxygen and lead to a faster crisis. If you can’t keep calm, it is easy to make mistakes in decision-making and miss the chance to escape. Keeping calm is very important for firefighters to escape from the plight, and the consumption is 1.87 times that of traveling on flat ground. In the fire environment, firefighters are highly stressed, the operational load is high, the human body is affected by high temperature, and physical energy consumption increases, and firefighters often need to climb and go down stairs, and the use time of air breathing apparatus will be further shortened. At the same time, there are obvious differences in the individual oxygen consumption rates among different people.
Due to the limited use time of air respirators, firefighters have a very short working time in the fire scene. The direction of travel, fire fighting and rescue, and evacuation must be very clear. The action is very decisive, and there is almost no room for error. Once there is a gap between the fire situation and the forecast , or a certain combat link encounters an emergency and is delayed, the firefighters will face the pressure of insufficient air supply of the air breathing apparatus, and every minute of delay may bring serious consequences.

2.2 The fire scene is complex and changeable
Fire-fighting and rescue is a high-risk post, and the environment of the fire scene is changing rapidly. With the development of society and economy, all kinds of new buildings and new technologies continue to emerge, high and low (high-rise buildings, underground buildings, large-scale complexes, petrochemical enterprises) fires increase, and new industrial and commercial building fires have large fire loads, large fire areas, There are many types of materials and high density of personnel. When firefighters attacked in close combat, they were often unable to evacuate as planned or the evacuation time exceeded expectations due to sudden changes in the fire situation and new risks and situations; the originally planned evacuation route was blocked due to local collapses, explosions or changes in the direction of fire spread; The large building area and complex structure may cause firefighters to lose their way in the fire scene, etc., which may cause the air in the respirator to be exhausted before the personnel are completely evacuated.
3 Emergency measures after the respirator air is exhausted
When the air in the respirator is about to run out, firefighters will be under great psychological pressure and must find a safe exit and leave the dangerous area in a short time. Once you can’t get out of the danger area in a short time, you will face the threat of suffocation. When it is found that the air in the respirator is about to run out, the following measures should generally be taken:
3.1 Remain calm and exercise strict breathing control When assessing that the remaining air volume is not enough to safely evacuate the fire, do everything possible.
May prolong the use time of residual gas. Firefighters should control their emotions, keep calm, stay away from high temperature and danger as much as possible, strictly control their breathing, and avoid unnecessary air consumption. Any impulsive and blind movement will speed up the consumption of oxygen and lead to a faster crisis. If you can’t keep calm, it is easy to make mistakes in decision-making and miss the chance to escape. Keeping calm is very important for firefighters to escape from dilemma, and it is helpful for firefighters to use all available conditions to increase the chance of escape. However, a calm mind and good breathing control are subject to the rigid constraints of physiological limits, and effective equipment is still urgently needed to provide protection.

3.2 Call for help in time and take appropriate measures to wait for rescue
When judging that the respirator is not enough to support safe evacuation, firefighters should not hesitate to send out a distress message, and send it at least three times so that the commander and comrades can receive the distress message. The distress information should include the department title, name, exact location (or the last location that can be determined) and the situation of distress. Then, according to the actual situation on the scene, decide whether to stand still and wait for rescue, or find an exit to a safe location and wait for rescue. In general, in residential buildings, it should be as close as possible to the external windows. If there is no external window nearby, it should be moved as far as possible to a relatively safe, easy-to-search, and clearly marked location for search and rescue personnel to find.
The problem with waiting for rescue is that the speed of emergency rescue is very limited. It is very fast for the search and rescue team to find the person in distress in 5-10 minutes in a dark environment. The time required for emergency search and rescue often exceeds the rescue window time. Under the pressure of running out of air, it is very difficult for firefighters to stay calm and often fail to make correct decisions, including determining their location and moving to a suitable location to wait for rescue, thereby exacerbating the dilemma.
3.3 Filtering the air with combat suits
After the air in the air respirator is exhausted, it is undoubtedly the worst choice to take off the mask and directly expose to the smoke of the fire. In an emergency, you should lean over and crawl on the ground. You can unplug the quick connector of the air supply valve and the air supply pipe, and insert it into the combat suit from the neck. On the one hand, you can use the air in the combat suit to supply breathing. Heavy combat suits can act as a simple air purifier. It is also possible to remove the air supply valve and directly cover the air intake of the mask with a combat suit or hood for air filtration.
Prostrate yourself on the ground to help firefighters get oxygen. According to a statistical study by Yale University, in a fire, when the oxygen content of the ceiling is only 8.7%, the oxygen content of the ground is still 19%).
The problem with using combat suits to filter air is that it can only play the simplest filtering role, cannot filter poisonous gas, and has very limited protection.
4 Design of emergency equipment after breathing apparatus air is exhausted
4.1 Basic structure of emergency equipment
4.1.1 Material selection
Emergency equipment can choose portable compressed oxygen or filter-type anti-virus materials. If the compressed oxygen is not properly packaged and protected, it will bring safety hazards, and the gas cylinders that can provide sufficient safety protection in the fire scene are not light in weight, small in size, and inconvenient to carry. Therefore, it is more practical to use filter-type anti-virus materials.
4.1.2 Basic structure
There are two ways to breathe through the filter type anti-virus material: one is to connect the quick interface of the air supply valve air supply pipe to the filter type anti-virus material for breathing; the other is to directly connect the filter type anti-virus material to the air inlet on the mask for breathing .
Breathing through the quick interface of the air supply pipe of the air supply valve is simple and quick to operate, but because the air supply valve is equipped with a decompression device, the breathing resistance through the air supply valve under normal pressure is very large, and the body is uncomfortable and difficult to use continuously. It is the most scientific choice to put the filter-type anti-virus material into a special container to make a canister, and design a standard interface matching the respirator mask on the can body. The design of the canister is the same as that of the gas mask, and the design standard of GB 2890-2009 “Respiratory Protection Self-Priming Filter Gas Mask” is applicable.
The canister includes a filter layer, an adsorption layer and a chemical treatment layer. The filter layer is composed of high-efficiency filter cotton and ultra-fine glass fiber or other synthetic materials, the adsorption layer is activated carbon, and the chemical treatment layer uses different detoxification agents for different poisonous gases. Generally, special activated carbons are loaded with targeted detoxification agents without a separate chemical treatment layer. Figure 1 shows a schematic diagram of the structure of a common canister.

4.2 Design points of the canister
Life-saving canisters for firefighters should have higher requirements than ordinary civilian canisters.
4.2.1 Strong anti-virus ability
Ordinary fire canisters can filter out 99.99% of smoke and absorb toxic vapors and some toxic gases. CO cannot be adsorbed, and CO can be oxidized to non-toxic CO2 by special chemicals. When using, the oxygen concentration in the environment is required to be no less than 18%. Considering the complexity of modern fires and the diversity of firefighters’ work scenarios, the canister should be designed with a composite multi-functional filter for firefighter protection to filter and process more types of poisonous gases.
4.2.2 The use should be safe and convenient, light in weight, small in size, and easy to carry
The weight of ordinary canisters is generally not more than 300g, which is convenient, compact and easy to carry. The design of the multi-functional filter for firefighters should also strike a balance between protection performance and portability. The total weight of the canister should be controlled within 500g to facilitate portability and avoid extra burdens for firefighters in combat. The canister body of the canister should be sturdy and strong, with fireproof performance, and it is safe and reliable to use in the fire field.
When the air in the respirator is exhausted, the firefighter can use the canister to switch to the filtering protection mode, and then discard the rest of the air respirator (gas cylinders, back support, etc.)
Escape fast.
4.2.3 The protection time and shelf life should be longer
Generally, the protection time of the canister should not be less than 30 minutes, so as to provide sufficient escape time for firefighters. The shelf life of the canister under sealed storage should not be less than 5 years to reduce the cost of use.
5 The necessity of setting up a canister as emergency equipment
5.1 Urgent needs in reality
Based on the high-risk nature of firefighting and rescue operations, the situation of air exhaustion of respirator cannot be completely avoided. As mentioned above, conventional emergency measures can play a very limited role, and in a short period of time, the use time of air respirator cannot be significantly improve. Therefore, in addition to the conventional emergency measures, it is necessary and urgent to design backup emergency equipment for firefighters that can play a greater role.
At present, the canister is not included in the firefighter’s personal protective equipment standards, and where conditions permit, it should be tested first to accumulate experience and data.
5.2 Powerful practical functions
When firefighters are evacuating, in most cases they are not necessarily in the most dangerous areas. When the respirator air is exhausted, the canister is sufficient to provide life safety protection. Even in smoke-covered areas, the use of a canister may still not prevent injury when the respirator is depleted of air, but immediate death may occur if the canister is not used.
According to the statistical research of relevant research institutions, the oxygen concentration at the floor of most fire sites is higher than 18%, which is in line with the use conditions of the canister. Even in an environment where the oxygen concentration is lower than 18%, the threat of toxic gases such as CO to people is much higher than that of hypoxia. In a hypoxic environment, the human body can barely support for a period of time, but in the face of poisonous gas, the human body can support it for a much shorter time.
The canister should only be used in the most urgent situations and does not conflict with the use of air respirators. Canisters are equipped to provide firefighters with an alternate chance of escape in the most critical situations, and canisters are not a substitute for breathing apparatus. However, no matter the circumstances, when the respirator air is exhausted, the canister will protect the life of the firefighter without any toxic effect. And in most cases, this protection is still very effective, and the canister has a strong practicality.
6 Summary
Using filter-type anti-virus materials, at the most critical moment, the firefighter’s positive pressure air respirator can be quickly switched to a gas mask, so as to strive for the last chance for firefighters to escape. There have been similar explorations abroad, but there is no research in China. and application. Under the existing technical conditions, the use time of the air respirator cannot be significantly improved in a short period of time, and the air exhaustion of the respirator on the fire cannot be prevented. The use of a canister is a very wise choice.
The canister is small in size and light in weight, so it will not be a burden for firefighters, but it can provide respiratory protection for firefighters at the most critical moment. As the last resort and reliance for firefighters to escape from the fire, the application and promotion of “canisters” is of great value to protect the lives of firefighters, and it is necessary and urgent.

【Abstract】This paper discusses the harm of low temperature to human body and the necessity of protection. The effects of fiber material, floc thickness, fabric structure parameters and air layer thickness on warmth preservation were analyzed. The authors put forward that low temperature protective clothing should be lightened, moisture permeable and active.

【Keywords 】 low temperature protective clothing; radiation heat; warmth; air permeability; low thermal conductivity

0 Preface
In low temperature environments, such as working in biopharmaceuticals, cables, low temperature test chambers, building materials, cold processing of metal castings, low temperature gas transportation, laboratory research, frozen food processing and any other places that prevent extreme cold, the body surface will lose heat. , causing injuries such as frostbite and freezing of human tissue, and severe cases will faint. Generally, the common clothing for low temperature protective clothing is the thermal clothing that resists above -40 ℃, and for the temperature below -40 ℃, ordinary protective clothing will limit the protection of the human body, so better protective clothing is required. Existing low-temperature protective clothing includes passive and active types. The passive thermal clothing is generally composed of three or more layers of outer fabric, thermal insulation batt layer, and comfort layer, and the outer fabric is usually covered with a waterproof and breathable membrane. The fabrics used in low temperature protective clothing should not only keep warm, but also have physical and chemical properties that do not change due to long-term low temperature. Because most fabrics are used continuously under ultra-low temperature conditions, the crystallinity of the fabric changes, resulting in the mechanical properties of the fabric. Change, conventional polyester or glass fiber has limited low temperature resistance, after -40 ℃, the fabric will be embrittled and cracked. Taking into account the needs of low temperature protection in different environments, phase change materials and coatings are used to make thermal fabrics (I5-61; in addition, the clothing fabrics should have good cold resistance, water resistance, snow and wind resistance, and can be used in extreme low temperature conditions. The performance of the bottom material will not change greatly. In addition, in the low temperature emergency or rescue, the low temperature protective clothing should not only have the function of keeping warm, but also have certain requirements on flame retardancy and strength.
This paper summarizes the test standards of low temperature protective clothing, and expounds the protective mechanism of low temperature protective clothing. Fiber, functional fibers can be added to the flakes, which can be functionalized while achieving warmth.
1 Standard for low temperature protective clothing
There are relevant standards at home and abroad when evaluating the effect of low temperature protection, among which the foreign standards are IS011092:1993 “Determination of thermal resistance and moisture resistance under steady-state conditions of physiological comfort of textiles”: ISO5085.1-1989 “Testing of thermal resistance of textiles No. 1″ Part: Low Thermal Resistance”: American Society for Testing and Materials ASTMD1518-2011 “Standard Method for Testing Thermal Conductivity of Textile Materials”: Japanese Industrial Standard JISL1096-2010 “Test Method for Woven Fabrics”, and different test standards correspond to different test methods. There are some structural differences. Domestically, the GB/T11048 2018 “Determination of Thermal Resistance and Moisture Resistance of Textiles under Steady-State Conditions for Physiological Comfort of Textiles” is used for thermal insulation testing, and the physical and chemical properties of clothing fabrics do not change under low temperature conditions. In the test comparison, Chen Xin et al. GB/T 35762-2017 “Test method for heat transfer performance of textiles”, GB/T11048-2018 “Determination of thermal resistance and moisture resistance under steady-state conditions of physiological comfort of textiles (evaporative hot plate method) 》The standard thermal insulation was compared and tested, and the thermal resistance measured by the evaporative hot plate method was greater than that of the flat plate method, but the test data of the flat plate method were more stable. In addition, most domestic tests use the warm body heating method to measure warmth retention.
2 The protection principle of low temperature protective clothing
Low temperature protective clothing fabrics are mainly clothing worn by the human body to maintain the normal body temperature of the human body when working in cold environments and extreme environments. The types of existing low-temperature resistant clothing are mainly passive and active: Among them, the passive low-temperature protective clothing mainly aims to prevent the rapid loss of heat in the human body and form a microclimate layer between the human body and the clothing fabric [9] Clothing fabric A large amount of still air is stored between the layers to block the conduction of heat. Since the thermal conductivity of still air is close to 0.02, its extremely low thermal conductivity will effectively isolate the heat transfer so that the heat will not be transmitted to the outside world, and the radiant heat generated by the human body will be reflected between the multi-layer clothing, reducing the transmission of radiant heat. Figure 1 shows the microclimate environment formed between the human body, clothing, and the outside world. Additionally the heat transfer capability of a single layer fabric affects the heat transfer from layer to layer. On the contrary, active low temperature protective clothing mainly uses advanced technology to convert other forms of energy into thermal energy to maintain human body heat, and also uses phase change materials to keep fabrics warm at low temperatures.

3 Factors affecting the thermal insulation performance of low temperature protective clothing
3.1 Fiber Materials
Fiber material is the primary consideration for protective clothing. Compared with active thermal clothing, hygroscopic heating fibers can be used. Such fibers achieve heating through the hygroscopic heat between macromolecular chains. In addition, phase change materials are added to protective clothing. Capsule phase change material, so as to achieve the effect of self-insulation. Hollow fiber is also a kind of active thermal insulation material, which uses the space between fibers to trap a large amount of still air to reduce heat loss3). In the external heating fibers, heating fibers can be used to store the heat in the form of internal energy by using external electric energy and solar energy, so as to play a role in keeping warm. Such fibers include electric heating fibers, solar heating fibers, etc.) Radiation absorption to achieve warmth.
Most passive thermal insulation materials are attached to fur, down, wool and cotton. These fibers have better thermal insulation properties and mainly rely on excellent bulkiness to increase the air cavity layer. This type of fiber material contains more air layers, and the thermal conductivity of the fiber is also low. Many manufacturers make full use of the low thermal conductivity between fibers to enhance the thermal insulation of the protective fabric). In the research on passive fiber materials, it is found that the thermal conductivity of fibers has a high impact on thermal insulation, and the air trapped by fibers is the key to thermal insulation. For this reason, Jia Juan et al. tested the moisture permeability, thermal insulation rate and thermal resistance of various natural fibers, and concluded that the defect of traditional thermal insulation materials is not due to insufficient thermal insulation, but because of poor moisture permeability and air permeability, etc. problems, pointed out that the use of fiber materials should pay attention to comfort. Used in different industries, such natural fibers can be used for fabrics worn by ordinary industry personnel in activities or work, while for some special industries, fiber materials are required to have better physical and chemical properties at lower temperatures, such as liquid nitrogen , metal device cold treatment protection, etc. This kind of protection should use fibers with lower thermal conductivity on the fiber material, and the fibers have better physical and chemical properties and flame retardancy. For this purpose, the performance tests of aramid products and polyimide products before and after liquid nitrogen treatment were carried out. The properties have not changed, and it is concluded that aramid products and polyimide products have better low temperature resistance properties. Therefore, such thermal clothing at lower temperature requires no change in fiber properties. On the other hand, the lower the thermal conductivity of the fiber material, the better the thermal insulation of the fiber.

3.2 Thickness of garment flake layer
The thickness of the low-temperature protective fabric determines the protective effect of the protective clothing. Due to the cold outside environment, the fabric needs to be filled with flakes inside the fabric to maintain the body temperature. Thickness, which not only increases the still air inside the garment, but also blocks the heat generated by the human body from diffusing to the outside. According to relevant research, it can be seen that the quality of the flake layer is under the same conditions, the thicker the flakes used, that is, the flakes with good bulkiness have better thermal insulation. And performance is better 19-200. Therefore, the thermal insulation performance test was carried out on this basis, and the thermal insulation performance test was carried out on polyester batting sheets with different thicknesses. It can be seen that the thermal resistance increases as the thickness of the flake layer increases, so when selecting the thickness of the flake layer, it can be selected according to the purpose of the clothing. of discomfort. The flakes used in extremely harsh environments and special industries often use fibers with low thermal conductivity, such as polyimide flakes, aluminum silicate felt, etc. Its excellent thermal insulation can effectively protect the human body from low temperature damage , In these industries, the outside temperature is often close to -100 ℃, and the flakes used at this time not only need to keep warm, but also need to resist the exchange of their own heat to the outside world [22]. In order to achieve the comfort of the human body, functional fibers can be added to the flake layer to be blended with other fibers to ensure that the flakes can increase their functionality and adjust the body temperature while keeping warm. Considering the comfort and mobility of the human body, the thickness of the flake layer can be controlled between 15 and 30mm. The lower the temperature, the thicker the flakes are required, but the flakes are not easy to be too thick, otherwise it will affect human activities.
3.3 Structural parameters of apparel fabrics
The thermal insulation of clothing fabrics is related to the thickness, density, bulk density and tightness of the fabric. Chen Lili et al. pointed out in their research on the thermal insulation and air permeability of the fabric structure parameters that the number of warp and weft yarns is less, the fabric structure is fluffy and thick, and the thermal insulation of the fabric is high. The better, and it is also concluded that the thermal insulation of the fabric decreases with the increase of the bulk density of the fabric under the same tissue structure parameters. In the organizational structure research, it is found that the order of thermal resistance of the fabric from large to small is: plain weave>2/1 twill>2/2 twill>3/1 twill>3/2 twill>satin weave, it can be seen that the outer fabric is structurally designed The use of a plain weave construction contributes to the thermal properties of the fabric. In addition, the smoothness of the surface of the fabric has different absorption of infrared rays. The surface of the fabric is smooth, the reflection of infrared rays is large, and the surface of the fabric is rough, the absorption of infrared rays is more, so the heat preservation is better. For this reason, filament can be used in the design of fabric structure It can be used with spun yarn to increase the roughness of the fabric, thereby achieving better warmth retention.
3.4 Air permeability and air layer thickness of protective clothing
Under the external environment and low temperature and humidity, the human body will produce sweat in the state of exercise, and it will be transmitted through the inner layer layer by layer. When the moisture conductivity of the clothing fabric is poor, the water will be taken away due to the good thermal conductivity of water. The temperature circulating in the human body reduces the protective performance, so the low temperature protective clothing should have good moisture permeability, which can quickly export sweat and avoid the body feeling stuffy. On the other hand, in the multi-layer structure, the thickness of the static air layer between the layers is the main way to cut off the heat exchange between the outside world and the body. Due to the arrangement of the flake material, there are many voids in the flakes, and a large amount of still air is contained in the voids, resulting in better thermal insulation of the clothing fabric. The inner layer is covered with a film to increase the waterproof and windproof properties of the fabric, and prevent the cold air from outside to take away the heat of the body. To maintain the thickness of its own air layer, the radiant heat convection heat loss between the layers of clothing fabrics needs to be small, and the number of layers of the flock layer can be appropriately increased to increase the thickness of the air layer. It can also add antibacterial fibers to the stretch layer to realize the functionalization of clothing fabrics.
4 The development trend of low temperature protective clothing
With the development of textile and chemical fiber technology, the continuous improvement of the properties of fiber materials and the maturity of some materials with low thermal conductivity, the development of low temperature protective clothing fabrics is not limited to existing materials, and can be made from lightweight materials, scientific structure, functional In the direction of rationalization, good moisture absorption and breathability, and the overall clothing is light, thin and comfortable, ultra-fine fibers (with a diameter of less than 5mm) can be selected as materials, and aerogels can also be selected. To increase warmth, graphene can also be used to achieve active warmth.
In the selection of fabric materials, different types of low thermal conductivity materials can also be mixed, so that each fiber can play a synergistic role, and functional materials can be added to functionalize the cryogenic protective clothing. Protective clothing should pay attention to fluffy in the selection of thermal flakes, but also design on the structure of fiber stacking, so that the flake layer retains more still air and improves the thermal insulation of protective fabrics. With the continuous advancement of new technologies, the preparation process of some microfibers will be mature. Since the superfine fibers are stacked, their bulkiness and warmth retention are better, and these microfibers are integrated into clothing with some self-heating, photoelectric combined thermal elements. In order to achieve thermal insulation and heating under low temperature conditions, to achieve double thermal insulation. In the structural design of clothing and fabrics, attention should be paid to thermal comfort, adjustability and movement to make clothing more comfortable.

【Abstract】 This paper systematically reviews the history of the development of the American spacesuit, and describes the latest commercial SpaceX spacesuit in the United States. SpaceX spacesuit by the private space exploration company (SpaceX) design and production completed, this spacesuit and traditional spacesuit focus on performance and ignore the appearance of different, in the appearance of a great breakthrough. However, the SpaceX spacesuit is only suitable for use within the spacecraft due to functional design limitations. By analyzing the design features of the SpaceX spacesuit, such as the appearance and fabric, combined with the trend of The Times, the future development of spacesuit is the key direction of high-tech multi-function and fit.
【Keywords】 spaceX space suits; In-cabin spacesuits; appearance design; the details show

0 Preface
For thousands of years, human beings have always been interested in space and have never stopped exploring. If human beings want to survive in the space environment, they must use related equipment to maintain the basic needs of life and provide a living environment for life. In addition to spacecraft, space suits are very important for astronauts. As the clothing worn by astronauts during their missions, space suits have functions similar to those of mini-spacecraft. Spacesuits can be divided into three categories according to their functions, namely（IVA spacesuit）, extravehicular spacesuit (EVA spacesuit) and（IEVA spacesuit） . The development of in-vehicle and extra-vehicle one-piece space suits is limited by early technological development, and now the extra-vehicle and in-vehicle space suits have been developed separately. The space suit in the cabin is also called the emergency rescue space suit. It is mainly used in the stages of launch and return. The space suit is used to ensure the oxygen required for astronauts to breathe and maintain the necessary survival pressure to ensure that the astronauts lose pressure in the cockpit. safety of life.
Looking back at the history of the development of human spacesuits in the past 100 years, spacesuits inevitably give people a clumsy and heavy feeling. This is mainly related to the nature of the aerospace industry. The traditional spacesuit design takes safety and functional requirements as the core starting point, and the cost is high, and the “appearance aesthetics” is the second priority. But with the advancement of the times and the commercialization of the space industry, designers will naturally think about how to make the appearance of space suits attractive. This paper makes a detailed statement on the functional reform of the SpaceX spacesuit as a commercial design clothing appearance, in order to provide some ideas for the development of future spacesuits.

1 In-cabin space suit
1.1 U.S. in-cabin spacesuits
In the early 1830s, American high-altitude pilot Persian presided over the development of the world’s first high-altitude pressure suit™, which laid the prototype of the future space suit research and development. In the 1860s, inspired by the high-altitude jet pressure suit of the U.S. Navy, the Mercury space suit was born. From the perspective of the development process of the US space suit, the development of the US space suit is influenced by the mission.
Beginning in 1981, NASA (National Aeronautics and Space Administration) began to use a new generation of extravehicular space suits. Due to the high cost of space suits, the American space suits no longer adopted tailor-made methods, but adopted Modular design ideas. That is, the number is determined through specific tasks, and by combining CEI (Contract End I-tems) modules of different sizes, the astronauts are finally provided with almost tailor-made clothing.
This method not only saves money significantly, but also facilitates astronauts to replace clothing components during long-term exploration missions. Table 1 summarizes the characteristic information of the major US in-vehicle spacesuit systems in different periods.

1.2 SpaceX spacesuit
Generally speaking, although different types of space suits have different fabrics, comforts, overall functions and appearance designs, most of them are bulky and complicated in appearance. With the development of the times, space suits are also facing major changes in appearance.
The spacesuit in the SpaceX cabin is also known as the “Star Man” spacesuit. In 2018, SpaceX used a dummy model called “Star Man”, wearing a spacesuit that only has shape but not function, and flew into space on a launch vehicle. The SpaceX spacesuit, as the first commercial cabin spacesuit to enter space, has undergone major changes in design. In 2015, SpaceX said it would develop a spacesuit. In 2017, Elon Musk published the first official photo of the SpaceX spacesuit on his private account for the first time. He pointed out that the spacesuit has been stress tested, but it is very rare to require the spacesuit to be functional and beautiful at the same time. matter. Therefore, in this process, they adopted a “reverse engineering” design method: first design the appearance of the spacesuit, and then consider how to meet the functional and protective requirements of air travel. It took Musk and Fernandez four years to finally complete this “Star Man”.
In 2020, Bob Behnken and Doug Hurley wore “SpaceX Dragon flight suits” and carried the Crew Dragon into space. And this is the first public appearance of the spacesuit. SpaceX spacesuits are tailored for astronauts to be functional, lightweight, and aesthetically pleasing, as well as provide protection against possible depressurization.

2 SpaceX spacesuit functional design
2.1 Structural Design
Structural design is the core of the spacesuit in the cabin. The SpaceX spacesuit consists of pressure suits, helmets, gloves, ventilation and oxygen supply components and some accessories. It is a functionally integrated clothing. Its structural shape is similar to that of traditional spacesuits, and it adopts a “soft” type structure in which the head and torso and limbs are connected together, and an open ventilation and oxygen supply method.
SpaceX spacesuits are custom-made for astronauts, and helmets are also custom-made using 3D printing technology. Customization allows both garments and helmets to perfectly fit the wearer’s body shape and size. The helmet is equipped with a communication system and control valves connected to various parts of the body. There is a button on the side of the helmet that controls the opening and closing of the mask. The helmet is attached to the mask, but traditional helmets have long been bolted to restrict the wearer’s head movement, resulting in the wearer only looking straight ahead and not looking to the side. Therefore, in the past, astronauts called this situation the “crocodile head” effect.
To this end, Jose Fernandez changed the upper neck part of the spacesuit helmet from bolts to hinges, which made these flight suits lighter and, at this time, provided the astronauts with a better field of view. The design of the SpaceX spacesuit offers a new way to solve this conundrum.
Different from traditional spacesuits, the “Xingxia” spacesuit has a flat appearance, because the designer uses the “hiding” formula to hide the external hoses, wires and raised knobs on the surface of the clothes. , The life support system interface and other line interfaces such as air and power connections are hidden by the rectangular cover above the knee of the right leg and will not be exposed on the surface of the garment. And the seat is equipped with clothing connection pipes, which greatly facilitates the operation of the astronauts.
For spacesuits, improving fit, flexibility, and ease of putting on and taking off can effectively guarantee its ergonomics. In terms of adaptability, SpaceX maximizes the adaptability of space suits through customized strategies, so that astronauts can carry out activities comfortably and flexibly when necessary. In terms of flexibility, the flexibility of spacesuit joints and gloves is the primary factor that restricts the ability of the suit to operate. The activities of astronauts wearing spacesuits are mainly limb activities, and clothing will have certain constraints on human activities. Therefore, the design of the joint is particularly important. The knee part of the SpaceX spacesuit has a suitable margin through the pleated design, which not only facilitates the bending of the human leg, but also makes it more concise and beautiful. In addition, the convenience of putting on and taking off the spacesuit is one of the basic requirements for the spacesuit.

2.2 Appearance design “Xingxia” belongs to the space suit in the cabin, which is only worn by the astronauts in the cabin when the manned spacecraft emerges. If the spacecraft is in danger of gas leaks or sudden changes in air pressure during flight, it must be able to protect the air pressure balance of the astronauts in the cabin. In addition, during the journey, astronauts need to wear the spacesuit in the cabin to move in the cabin, so the spacesuit in the cabin should not be too bulky and should ensure the flexibility of the wearer. Therefore, compared with extravehicular spacesuits, in-vehicle spacesuits are generally lighter, and the appearance is easier to make into a compact design.
Compared with the traditional American spacesuit, because to ensure the comfort of the astronauts when they bend their bodies, they will be designed with sufficient margins, which directly causes the astronauts to appear heavy and bloated when standing. In general, SpaceX’s spacesuit is different from the ergonomic design, and the appropriate margin design makes the clothing look neat even when the astronaut is upright, and is influenced by pop culture and science fiction works in interstellar travel. Influenced by the shape, the clothing is mainly black and white as a whole, and the overall design takes into account the ability and fashion. The black and gray pieces on the side can visually modify the body shape.
It is aerodynamically designed with a dividing line extending from the shoulder blades to the upper part of the knees. The sleek black-and-white look of the SpaceX spacesuit makes for a streamlined, stylish and visually striking look. Visually, the SpaceX spacesuit is an upper and lower suit with a separate helmet and shoes. But in fact it is a one-piece design, the helmet is connected to the body, and the feet are made of black fabric to make the shape of boots, which are part of the body itself. As a one-piece suit, it not only has a streamlined and lightweight appearance, but also can meet the needs of the wearer’s activities in the cabin, and can also ensure the safety of the wearer’s life in the cabin. As shown in Figure 5, the shoulders of the SpaceX spacesuit have straight and smooth lines in appearance, and the body-fitting design makes the shoulders more fashionable.

2.3 Fabric selection
Space suits face a series of functional challenges, and the first problems to overcome are pressure and temperature. As altitude increases, air pressure and air temperature will decrease significantly. This puts forward requirements for the design of functional fabrics of space suits, that is, the core point of the design of space suits is the protection requirements for the decompression environment.

2.3 Fabric selection
Spacesuits face a series of functional challenges, and the first problems to overcome are pressure and temperature. As altitude increases, air pressure and air temperature will decrease significantly. This puts forward requirements for the design of functional fabrics of space suits, that is, the core point of the design of space suits is the protection requirements for the decompression environment.
EMU (extravehicular mobility unit) is a new type of space suit, which is developed on the basis of the Apollo space suit and consists of a pressure suit and a life support system. Due to its unique environmental characteristics, pressure clothing needs to be composed of multiple layers. Similarly, in order to cope with the environmental changes in space, the “Xingxia” spacesuit uses a similar fabric to the international active-duty extravehicular exploration device EMU, which also has a multi-layer structure.
The outer layer of the spacesuit uses a variety of polymer materials including “Nomex” and “Teflon”. “Nomex” series products have superior high temperature resistance, flame retardant, non-toxic, and better mechanical properties. The “Teflon” material is also a material that can withstand high temperatures and allow for quenching, quenching, and high pressure. Both materials are developed by DuPont and are widely used in aerospace and other national economic fields. These special materials make “Xingxia” fireproof, waterproof, dustproof and oil proof, and also resistant to wear and tear. The white part of the surface is made of DuPont’s “Teflon” material, which was used for the outer layer of the “Apollo” spacesuit. Teflon is widely used, not only for soft materials such as textile fabrics, but also for various hard materials. The black part also uses DuPont’s “Nomex” material. This material is commonly used in racing suits, and also functions similarly to DuPont’s “Kelvar” material once used on NASA’s orange spacesuits.
The main function of the construction and material of the inner multi-layer material is to ensure the balance of air pressure inside and outside the wearer’s body. In the case of pressure imbalance in the cabin, the safety of the wearer’s life can be guaranteed. Back in 2017, the suit passed the rigors of double vacuum pressure.
The gloves and bodice of the SpaceX spacesuit are also tailored in such a way that they become part of the overalls. Intelligence and automation are the trend of clothing development, and spacesuits are technology-integrated clothing. SpaceX spacesuits use glove touch screen technology to match existing touch screen technology.
technology, so that the wearer can control the spacecraft through its interaction with the touch screen. The commonly used touch screen gloves refer to the special gloves used to operate capacitive touch screen products in winter, which realizes many functions such as protection and technology. From the design point of view, the inner layer of the touch screen glove is made of antistatic fiber. Through the test of charge amount and yarn test, it meets the charge amount of the touch screen and the inspiration degree of the touch screen glove 10, and the unique weaving is carried out through the computer to complete the space suit. The final form of the glove. As a result, the spacesuit is more automated, which also provides higher safety for astronauts to enter space.
2.4 Functional Innovation
A major innovation in SpaceX’s spacesuits is that SpaceX’s spacesuits dissipate heat from the astronauts’ bodies through air cooling. Prior to this, NASA’s current EMU used water-cooled heat dissipation. The water-cooled tube was adsorbed on the astronaut’s skin to absorb sweat to keep the body dry and absorb heat to keep the astronaut’s body temperature lower than the core temperature of the human body. Air-cooled heat dissipation has higher safety, not only can it avoid water damage to astronauts, but switching to air cooling means that the cooling medium is harmless in the event of leakage. But at the same time, the use of air-cooled spacesuits will increase power consumption, because air is less efficient at removing heat than water, and the pump requires more power. 3 Summary
With the development of the times, industrial changes have brought about major changes in space suits. Space suits have gradually changed from the traditional “protection and functionality as the mainstay, supplemented by aesthetics” to “both functionality and aesthetics”.
In this regard, SpaceX has promoted the development of spacesuits in the cabin. Although it may only be a small step forward, it is not a historic change, but it is a small step that has been realized and has practical significance, and may herald future trends. The beginning of change. For the innovation carried out by SpaceX, all aspects can not only learn from its design ideas, but also promote the continuous development of the spacesuit industry and the industry.

——Interpretation of GB 39800.4-2020 Specification for Personal Protective Equipment Part 4: Non Coal Mine Mountains 【Abstract】Personal protective equipment is an important line of defense to maintain public safety and work safety, and it is also an important guarantee to guard the safety of workers’ lives and occupational health. The release and implementation of GB 39800.4-2020 Specifications for the provision of personal protective equipment -Part4: Non-coal mines standard will play a positive role in promoting the safety and health of workers in the non-coal mining industry. This paper explains the background, scope and main contents of the standard, in order to provide reference for better implementation of the standard. 【Keywords 】 personal protective equipment; provision; Non-coal mines; safety; occupational health

0 Preface
Personal protective equipment is a general term for various items worn and equipped to prevent physical, chemical, biological and other harmful factors from harming the human body. It is the last line of defense to protect the safety and health of individuals. In the past, personal protective equipment was called labor protection articles or labor protection articles, which were mostly used in production labor. The current personal protective equipment is not only this, but also involves personal protective equipment for military, police and firefighting, as well as personal protective equipment for public health emergencies, natural disasters, accident disasters, social security incidents and other rescue work. With the deepening of reform and opening up and the development of socialism with characteristics of the new era in my country, the market demand for personal protective equipment has become larger and larger, and the application fields have become wider and wider, but some systemic problems in the field of personal protective equipment have gradually emerged. , such as the lack of overall overall planning and planning, such as laws and regulations to ensure the safety and health of emergency personnel, such as the provision of personal protective equipment, etc. Although my country has successively promulgated a series of national standards for the equipment of personal protective equipment ((2-31), these national standards are recommended in nature and are voluntarily adopted through economic means or market regulation, and lack legal effect. GB 39800.4-2020 ” “Personal Protective Equipment Specifications Part 4: Non-coal mines” standard was released on December 24, 2020, and officially implemented on January 1, 2022. It is a mandatory national standard for personal protective equipment, and is a non-coal mine industry personal protective equipment. Equipped with the basis and guarantee.
1 Standard project background
The non-coal mining industry is a resource and basic industry that has an important impact on economic and social development. Especially in recent years, with the increasingly complex international situation and the increasing size of my country’s economy year by year, the market demand for mineral resources has continued to grow. The annual output value of the non-coal mining industry has reached hundreds of billions of yuan, with hundreds of direct employees. million people. The total number of non-coal mines is large. As of the end of 2017, there were 44,998 non-coal mines nationwide, including 37,845 metal and non-metal mines (29,007 open-pit mines accounted for 76.6%, and 33,156 small-scale mines accounted for 87.6%). Underground mines with more than 30 people in a single shift (1,072), open-pit mines with a slope height of more than 200m (89), and overhead warehouses have the highest accident risk, and are prone to serious production safety accidents involving mass deaths and injuries. The object of the key supervision of the safety production supervision department. In 2017, a total of 407 production safety accidents of various types occurred in non-coal mines across the country, and 484 people died. Figure 1 shows the trend of the total number of non-coal mine accidents and the number of fatalities from 2013 to 2017. The top ten regions in terms of accident fatalities from 2013 to 2017 are Yunnan, Liaoning, Guangxi, Hunan, Hubei, Inner Mongolia, Jiangxi, Sichuan, Shaanxi, and Xinjiang, as shown in Figure 2. In 2017, there were 259 accidents and fatalities in the above-mentioned regions. 288 people, accounting for 63.6% and 59.5% of the total number of non-coal mine accidents in the country in 2017, respectively.
From the statistics of 2014, there were 640 fatalities in accidents in 2014, accounting for nearly 10% of the total fatalities in industrial, mining and commercial accidents. The number of deaths caused by lack of or defective personal protective equipment has also accounted for 10% of the total number of deaths in industrial, mining and commercial accidents.
The reason is not caused by the lack of personal protective equipment product standards in our country, but the lack of mandatory national standards for personal protective equipment equipment. Enterprises have no basis for personal protective equipment equipment, and relevant departments have no basis for law enforcement. The number of deaths due to missing or defective personal protective equipment remains high.

From a legal perspective, my country’s regulations on personal protective equipment are all
There are clear regulations, such as Article 45 of the “Safety Production Law”; Article 54 of the “Labor Law”; Articles 22 and 25 of the “Occupational Disease Prevention Law”. GB/T 29510-2013 “Basic Requirements for Personal Protective Equipment”, which puts forward general requirements for the identification principles and methods of hazardous and harmful factors, procedures for personal protective equipment, management and training, etc., but it lacks specific industries and specific types of work. Equipped. And because it is a recommended national standard, it cannot provide specific staffing guidance and staffing constraints for workers in various industries.
In the second half of 2016, entrusted by the Policy and Regulation Department of the former State Administration of Work Safety, the National Personal Protective Equipment Standardization Technical Committee organized the Shanghai Institute of Work Safety and other units to conduct a special survey on the equipment of personal protective equipment in the non-coal mining industry. . The survey adopted various methods such as field research, discussion, exchange and questionnaire survey, and the survey content involved the production, testing and inspection, certification, equipment, management and use status of personal protective equipment. The survey found that the equipment standards of the non-coal mining industry are uneven, the equipment that should be equipped is not equipped or not fully equipped, and some positions or types of work are even mismatched, and there is a lack of unified standards and standards. The standard for the equipment of personal protective equipment in the coal mining industry is to standardize the equipment and management of personal protective equipment. 2 Scope of application of the standard
GB 39800.1-2020 “Personal Protective Equipment Specifications Part 1: General Provisions” stipulates the overall requirements for the equipment of personal protective equipment (ie labor protection articles), and the “Personal Protective Equipment Specifications Part 4: Non-coal mines” standard is equipped for the industry The specific implementation standards should be used in conjunction with the “Personal Protective Equipment Specifications Part 1: General Provisions”. Therefore, it is clearly pointed out in the general requirements that the principles and management of personal protective equipment should be implemented in accordance with the “Personal Protective Equipment Specifications Part 1: General Provisions”.
The “Personal Protective Equipment Specifications Part 4: Non-coal mines” standard is applicable to non-coal mines, including metal mines, non-metal mines, water and gas mines, and energy mines other than coal mines, oil and natural gas. Employers and their employees personal protection Equipment allocation and management. Not applicable to the equipment and management of fire-fighting personal protective equipment for employers in non-coal mining industries. 3 Main content of the standard

3.1 General Requirements
GB 39800.1-2020 “Personal Protective Equipment Provisioning Specifications Part 1: General Provisions” specifies the overall requirements for the provision of personal protective equipment (i.e. labor protection equipment), including provisioning principles, provisioning procedures, identification and assessment of workplace hazards, personal protection Equipment selection, traceability, scrapping and replacement, training and use, etc. The “Personal Protective Equipment Specifications Part 4: Non-coal mines” standard is the specific implementation standard for the non-coal mining industry. The principles, equipment management and equipment procedures of personal protective equipment are in accordance with GB39800.1-2020 “Personal Protective Equipment Equipment Specifications Part 1” Section: General Provisions Implementation. 3.2 Identification and Evaluation of Hazardous Factors The identification of hazardous and harmful factors is the premise and basis for the correct equipping of personal protective equipment. The “Personal Protective Equipment Specifications Part 4: Non-coal Mines” standard is based on the requirements of GB39800.1-2020 “Personal Protective Equipment Specifications Part 1: General Provisions” and GB/T13861-2009 “Classification of Hazardous and Harmful Factors in the Production Process and Code”, and combined with the characteristics of safe production in the non-coal mining industry, firstly put forward the overall principles of identification and evaluation of hazard factors. At the same time, two identification methods for hazard factors are provided, which can be combined with Table 1 according to the type of work, or refer to Appendix A for identification of hazard factors according to the type of work. A hazard assessment is then carried out on the basis of the identified hazard factors as a basis for selecting the appropriate personal protective equipment.
The main operation categories involved in the production process and the harmful factors caused by them are identified, and the labor protection articles applicable to each operation category are summarized: the employer should combine the characteristics of safe production in the industry, Identify and assess the hazard factors that may be involved, and use this as the basis for selecting the appropriate personal protective equipment. Different enterprises, different production processes and different degrees of automation, even the same type of work may be equipped with different personal protective equipment.
For example, in the metal mining process, cyanide is widely used as a solvent for metals such as gold, silver, and copper. Hydrogen cyanide gas is also easily generated in the cyanide solution, and contact with the solution can also irritate the skin. Cyanide can damage the heart and brain and cause death. Low-level exposure to cyanide can cause long-term health effects such as difficulty breathing, chest pain, vomiting, blood changes, headaches, and goiter. Therefore, the practitioners must be fully protected during the above process, including breathing and skin.
3.3 Provision of personal protective equipment
The equipment of personal protective equipment in the non-coal mining industry, due to the complexity of various types of work, cannot be compelled to specify what kind of personal protective equipment should be equipped for each type of work. of personal protective equipment. However, in order to facilitate the provision of personal protective equipment for employees in non-coal mining industries, two methods are given in the standard informative appendix:
a) Combining the hazard factors and hazard assessment results identified in Table 1 according to the job category, and the applicable personal protective equipment recommended in Table 1, combined with the protective position, protective function, scope of application of the personal protective equipment and the suitability of the protective equipment to the user , select the appropriate personal protective equipment.
b) Execute with reference to Appendix B. For the types of work not covered in Appendix A, the employer shall identify and evaluate the hazard factors according to the operation characteristics of the type of work, and equip corresponding personal protective equipment according to the requirements of the “Personal Protective Equipment Provisioning Specification Part 1: General Provisions”.
Employers can equip personal protective equipment according to the type of work or type of work, or a combination of the above. 3.4 Appendix
The two appendices of the “Personal Protective Equipment Specifications Part 4: Non-coal mines” standard are informative appendices, of which Appendix A lists the typical types of work and hazard factors in the non-coal mining industry. The types of work and their classification in the non-coal mining industry are mainly based on the “Occupational Classification of the People’s Republic of China (2015 Edition)” [8] Appendix B specifies the equipment of personal protective equipment for various types of work in the non-coal mining industry. According to the hazard factors of various types of work, and combined with the protective function and scope of application of personal protective equipment, the standard provides recommendations for the specific equipment of personal protective equipment for each type of work. Among them, it is necessary to specify:
1) The date of the longest replacement period of personal protective equipment is calculated from the date when the personal protective equipment is issued to the operator (see the issuance and use records of personal protective equipment); the longest replacement period can be based on the product manual, expiration date, and actual use time , work intensity, wear conditions, etc. are appropriately shortened.
2) If the temperature difference between seasons in the area where the enterprise is used for personal protective equipment varies greatly, protective equipment for spring, autumn, winter and summer can be configured according to the season, and the maximum replacement period should also be changed accordingly.
3) Personal protective equipment such as self-contained open-circuit compressed air respirators, seat belts (including other fall protection products), long-tube respirators can be configured for teams.
4) Enterprises using personal protective equipment should increase or decrease some functions according to the characteristics of the post and the corresponding dangerous and harmful factors. 4 Conclusion
The release and implementation of the “Personal Protective Equipment Specifications Part 4: Non-coal mines” standard provides guidance and constraints for the equipment of personal protective equipment in the non-coal mine industry, and provides supervision and supervision for the equipment of personal protective equipment for supervisors. The basis for law enforcement is also an important means for enterprises to implement the equipment and management of personal protective equipment. In addition, “Personal Protective Equipment Specifications Part 4: Non-coal mines”, as my country’s technical regulations, is also an important supporting document for the new “Safety Production Law”. convoy.

——lnterpretation of GB 39800.1-2020 Specification for Personal Protective Equipment Part1 ：General Provisions

【Abstract】This paper analyzes and explains the general situation， revision background and revision content of GB
39800.1-2020 specification for the allocation of personal protective equipment Part 1:generalprovisions.
【Keywords】individual protection ； Equipment； standard；unscramble

1.Background of the standard development
China has the largest working population in the world, with 775 million people employed nationwide in 2019, and most workers have careers that exceed one half of their life .One-half of the life cycle. At present, China is in the stage of rapid development of industrialization and urbanization, the safety production and occupational disease prevention and control problems accumulated in the previous decades of rough development gradually emerged, will face many new problems and new challenges. First, the number of reported cases of occupational diseases remains high, and by the end of 2020, the cumulative number of reported occupational diseases nationwide has reached nearly one million cases. Due to the low coverage of occupational health inspection and imperfect employment system, the actual number of cases is much higher than the number of reported cases. Second, the current situation of production safety is still in a period of climbing over the hurdles. 34,000 production safety accidents occurred in China in 2020, and more than 27,400 people lost their lives. In addition, with the development of technology, new hazards continue to emerge, a variety of new safety and health issues have caused widespread concern among workers and all sectors of society, old and new problems and conflicts intertwined, work safety and occupational health face multiple pressures.

Personal Protective Equipment (PPE) is an important industrial product to ensure labor safety and is the last line of defense to protect the lives and health of hundreds of millions of workers. Huang Yifu and other researchers found that 15% of production casualties occurred when workers did not wear PPE or did not wear PPE correctly. Yang Ying randomly selected nine manufacturing enterprises in Beijing and found that only one enterprise met the PPE requirements. Zhang Qunfang surveyed 159 small and micro enterprises in Shenzhen and found that the rate of setting up the PPE management system was only 57%. In addition, the rate of individual protective equipment is also very low, such as 43% for gas masks and 21% for protective glasses, which reveals that there is a big problem in the management of individual protective equipment in China. How to solve the problem of individual protective equipment in the employer’s equipment, so that individual protective equipment such as “life-saving” equipment really equipped to the hands of each operator who needs protection, so that it really plays the role of “last line of defense”, is to solve the current safety in China One of the important means to solve the serious situation of production and occupational disease prevention and control, and the key to solving the problem of equipping is the development of mandatory equipment standards”. Compared with European and American countries, before December 2020, China lacks a standard for the systematic regulation of the management of individual protective equipment. As soon as possible to develop individual protective equipment and management standards, to fill the national mandatory standards in individual protective equipment management gaps in our country, for the majority of practitioners of individual protective equipment and management to provide equipment, law enforcement and supervision of the basis, and for our production enterprises to provide individual protective equipment with guidance and equipment constraints, become individual protective equipment management urgent problem.
In such a background, the National Technical Committee of Individual Protection Standardization organized Beijing Institute of Labor Protection Science and other units drafted GB 39800.1-2020 “Individual protective equipment equipment specification part 1: general rules”. The standard was promulgated on December 24, 2020, and will be implemented on January 1, 2022. In order to help the majority of readers to better understand the standard, the author is now interpreting it.

Interpretation of the content of the standard
1.1 Scope of application
GB39800.1-2020 “Individual protective equipment specification Part 1: General” applies to the provision and management of individual protective equipment for each user unit, not for each user unit with individual protective equipment for firefighting and management, the applicable user unit, refers to the enterprises, institutions and individual economic organizations and other units in China, which is consistent with the People’s Republic of China Occupational New Prevention and Control Law” (People’s Republic of China Service Act) and other laws into the object of application is consistent, due to the field of firefighting XF621-2006 “firefighters personal protective equipment equipped with standards” this mandatory industry standard, in order to avoid the standard cross-repeat, clear that the standard does not apply to fire products equipped.
1.2 Terminology and definitions
The standard has developed four terms, including individual protective equipment, occupational hazard factors, tracking the source of the lake, paragraph number. Among them, in order to facilitate the understanding of front-line employees and increase the convergence of the standard, GB/T12903 – 2008 “individual protective equipment terminology” 3.1 “individual protective equipment” definition, adding the “labor protective equipment The definition of “labor protective equipment” has been added. The definition of “occupational hazards” combines the “risk factors” of the “Law of the People’s Republic of China on Work Safety” and the “harmful factors” of the “Law of the People’s Republic of China on Prevention and Control of Occupational Diseases”. On the basis of the “Occupational Safety and Health Terminology” of GB/T15236-2008, the definition of “Occupational Hazard Factors” has been changed to “Hazardous Factors”, which covers a more comprehensive scope. The definition of “tracing lake source” is based on the “General Office of the State Council on accelerating the construction of important product tracing system” (Guo Ban Fa (2015) No. 95) in the definition of the construction of the tracing system, to modify the development.
1.3 Principles of individual protective equipment equipment
The standard specifies the basic requirements of the employer for individual protective equipment, summarized in the following six principles: First, the principle of compliance. When there are occupational hazards and risks in the workplace, the employer should be equipped with individual protective equipment, which is clearly stipulated in the Labor Law of the People’s Republic of China, the Occupational Disease Prevention and Control Law of the People’s Republic of China, the Work Safety Law of the People’s Republic of China and other laws and regulations, and is also equipped with the most basic requirements. Article 54 of the Labor Law of the People’s Republic of China stipulates that: the employer must provide workers with labor safety and health conditions in accordance with national regulations and necessary labor protective equipment, and workers engaged in occupational hazards should undergo regular health checks. Occupational Disease Prevention Law of the People’s Republic of China, Article 22: The employer must adopt effective protective facilities for occupational diseases, and provide workers with personal use of protective equipment for occupational diseases. Employers provide workers with personal protective equipment for occupational diseases must meet the requirements of the prevention and control of occupational diseases; does not meet the requirements, shall not be used. Article 45 of the Work Safety Law of the People’s Republic of China stipulates that production and operation units must provide employees with labor protective equipment that meets national standards or industry standards, and supervise and educate employees to wear and use them in accordance with the rules of use.
In addition, the individual protective equipment must meet the requirements of national standards or industry standards, that is, the equipment purchased by the employer should be qualified products. This is the minimum requirement to ensure that the product has the basic protective performance.
Second is the principle of effectiveness. Operators in wearing individual protective equipment, people, equipment, the environment that constitutes a microsystem, which Equipment is the central link to resist environmental harm to people. To ensure that the protection of the equipment is effective, there are three requirements: first, to adapt to the external environment, that is, to adapt to the environmental conditions of the workplace, operating conditions, the presence of hazardous factors and the degree of harm. There is another layer of meaning here, do not over-protection, such as when you can be equipped with protective masks, it is not necessary to be equipped with air respirators. Secondly, it should be suitable for the operator, such as respirator fitting mask to fit the wearer’s face, protective clothing to “fit”, protective shoes to “fit”, protective gloves to ensure that the wearer’s hands have a certain degree of flexibility. Finally, the individual protective equipment itself should not lead to other additional risks, such as the material or structure of the equipment can not cause harm to the human body.
Third, the principle of comfort. Individual protective equipment should not only be “prevented” but also “wearable”. Personal protective equipment as workers wear the necessities of daily work, its comfort performance is very important. In the daily inspection and research process, front-line workers often reflect the comfort of individual protective equipment is not good, poor operability, coupled with the harsh working environment and heavy workload, greatly increased the body load. Many workers reflect that although some individual protective equipment has a good protective function but wear after the uncomfortable, inconvenient, affecting the normal work, and sometimes bring other aspects of safety risks. Such as some labor protection shoes wear not only feel bulky, but also gnawing feet, due to poor breathability leads to rotten feet, etc.. Some dust masks due to resistance, workers are difficult to wear for a long time in high-intensity work, etc.. Therefore, the standard especially proposed in the premise of effective protection, pay attention to the principle of comfort.
Fourth, the principle of compatibility. Workplace hazards are often not a single, but a variety of hazards coexist, which then requires a variety of individual protective equipment to cooperate with the use. In the process of equipping, consider the compatibility and functional substitution between equipment, such as helmets and earmuffs, myopic eye competition or protective glasses and full face shield, full-body protective clothing and air exhaler, etc.
Fifth, the principle of coverage. The standard provides that the employer is not only responsible for the outfitting of the unit’s regular employees, but also to cover its use of labor assigned to create workers, temporary employment and the admission of interns. The Law of the People’s Republic of China on Work Safety stipulates that production and operation units that use dispatched workers should include the dispatched workers in the unified management of the unit’s employees: if they receive internships for secondary vocational schools and higher education students, they should provide the internship students with appropriate education and training on work safety and the necessary labor protection supplies. For other outsiders allowed to enter the workplace, including visitors, inspectors and other personnel, should also be included in the scope of management of individual protective equipment equipped.
Sixth is the principle of articulation. Individual protective equipment standards are a series of standards, including a general rule and a series of sub-standards. The general rules are mainly from the overall provisions of the “how to match” and “how to manage” the problem. Each sub-rule is based on the characteristics of each industry, focusing on the “how to match” the problem of regulations. In the standard Appendix A, according to GB/T4754-2017 “National Economic Classification” and the characteristics of China’s national economic industry individual protection needs, the planning of electric power, electronics and other 10 industries of individual protective equipment sub-rules equipped with standards, including petrochemical natural gas, gold non-ferrous, non-coal mining 3 industries with national standards (standard number are 39800.2-2020, GB39800.3 – 2020, GB39800.4-2020) has been promulgated on December 29, 2020, and synchronized with the implementation of the general rules. The standard 3.6 provisions of the standard and the national standards for the equipment of individual protective equipment in various industries for the interface, the provisions of the use of units should be based on the standard combined with the industry’s individual protective equipment with national standards for the equipment and management of individual protective equipment: no industry individual protective equipment with national standards, should be in accordance with the requirements of the standard for individual protective equipment and management.

1.4 Individual protective equipment (PPE) equipment procedures
The standard’s PPE equipment procedures section specifies how to equip PPE, including three parts: equipment process, workplace hazard identification and assessment, and PPE selection.
1.4.1 Equipping process
The flow chart of individual protective equipment in this standard is based on the labor protective equipment selection procedure in the former State Administration of Safety Supervision “Labor protective equipment management specification for employers”, and combined with the actual situation and development trend of China’s individual protective equipment management, including 14 procedures: determine the scope of identification, and the identification and assessment of hazard factors: determine whether to cause harm to the human body and its hazard degree; determine to take engineering or management measures and confirm whether they can be completely eliminated; whether the need for individual protective equipment: according to the results of the hazard assessment to select the appropriate individual protective equipment: determine the manufacturer or distributor: verify the product information and national tracking tide source system information is consistent: the acquisition of individual protective equipment; individual protective equipment acceptance, to determine whether it meets the national or industry standards: individual protective equipment Storage and archiving: Issuance of PPE: Training on wearing, use and maintenance of PPE: Correct wearing of PPE: Preservation, maintenance, inspection and disposal of equipped PPE.
In this procedure, the following three principles are reflected: First, the identification of hazard factors and hazard assessment is the premise and basis for the correct provision of individual protective equipment: Second, when there are hazard factors in the workplace, the first consideration is to take engineering or management measures to eliminate occupational hazards in the workplace, individual protective equipment is the last means of consideration: Third, individual protective equipment can not eliminate the risk, only It is the last line of defense against risk, but not the bottom line of defense, because each individual protective equipment has its own white protective limit. When the results of the hazard assessment exceeds its protective limits, other measures should be taken, such as stopping operations.
1.4.2 Identification and evaluation of workplace hazards
The identification of hazard factors is the premise and basis of the correct equipment equipped with individual protection, effective and adequate identification of hazard factors, can be targeted to develop preventive measures to achieve the prior control of the risk of hazards, in order to eliminate or reduce the degree of harm.
1) Identification principles
The standard puts forward two basic principles of workplace hazard identification.
First, it should be based on adequate. First, based on existing national laws, regulations, standards, followed by professional knowledge, and finally, based on the actual situation, including different workplaces, production processes, operating environments, etc.. The combination of laws and regulations, theory and practice, in order to be based on adequate.
Secondly, it is necessary to consider comprehensively. Should be all kinds of factors in production and operation activities, including personnel, equipment and facilities, the use of materials, process methods, environmental conditions, management systems and other systematic analysis. Not only to analyze the normal production operation of the hazards, but also to analyze the technology, materials, processes and other changes, equipment failure or failure, personnel operating errors and other circumstances that may produce the hazards.
2) Identification methods
First, the basic method. The standard proposes that on-site investigation, measurement, access to relevant records, inquiries and communication can be used to analyze the hazard factors in the operating environment. At the same time, the standard also gives two optional methods: one is based on the type of work engaged in the identification of hazard factors. Appendix B of the standard gives the common categories of work and may cause accidents or injuries. The standard in accordance with the working conditions in the operating environment and may cause accidents or injuries listed 35 major categories of work, the Division gives a description of the categories of work, and may cause accidents or injuries, the employer can combine the standard in Table B.1, according to the type of work performed by the operator, to determine the possible accidents or injuries. At the same time, if the actual work involves a number of operational features, that is, comprehensive operations. The standard points out that in the comprehensive operation, the employer can be equipped with multiple or multifunctional individual protective equipment for the operator according to the characteristics of the operation. Second, the employer directly identify the hazards according to the work of the staff. Appendix C of the standard lists the possible hazards and harmful factors of the production process. The appendix is quoted from GB/T13861-2009 “Production Process Hazardous and Harmful Factors Classification and Code”, the scope of application of the standard clearly states that “applicable to all industries in the planning, design and organization of production In the scope of application of the standard, it is clearly stated that “applicable to all industries in the planning, design and organization of production, the prediction of dangerous and harmful factors, prevention The identification and analysis of the causes of casualties, also applies to occupational safety and health information processing and exchange. It is also applicable to the processing and exchange of occupational safety and health information”. Therefore, it can be used as a reference for the identification of workplace
Therefore, it can be used as a reference for the identification of hazard factors in the workplace.
Second, the analysis approach. The standard proposed in the identification of hazard factors, can be analyzed from the following aspects: a) normal working conditions: b) abnormal working conditions: c) personnel work activities: d) equipment procurement, storage and transport, and operation, repair and maintenance of equipment and facilities; e) raw and auxiliary materials, intermediate and final products: f) production, construction processes: g) environmental conditions: h) management system: i other auxiliary activities and contingencies, this article is actually a further gate to the standard 4.2.1.1b) clause.
3) Hazard assessment
Hazard assessment is to identify the degree of harm of harmful factors to assess the analysis, as a basis for the selection of individual protective equipment protection function and protection level. Hazard assessment is a more complex system, there are a variety of assessment methods, in the standard only put forward some normative requirements, the specific operation can refer to GB/T27921-2011 “risk management risk assessment techniques” and other literature.
1.4.3 Individual protective equipment selection
Based on the identification of workplace hazards and the results of hazard assessment, the standard requires that the individual protective equipment should be combined with the protection parts, protection functions, the scope of application and protective equipment.
Based on the identification of workplace hazards and hazard assessment results, the standard requires the selection of appropriate individual protective equipment, taking into account the protective parts, protective functions, scope of application and suitability of the protective equipment for the operating environment and users. The standard on the current commonly used PPE is divided into nine categories, including head protection, eye and face protection, hearing protection, respiratory protection, protective clothing, hand protection, foot protection, fall protection and other protection, and the nine categories of 49 kinds of PPE product standards, protective functions and reference scope of application, so as to facilitate the selection of PPE when equipped.

1.5.PPE equipment management
After the individual protective equipment is equipped, it is the problem of how to manage. The management of individual protective equipment is an essential part of individual protective equipment. If the individual protective equipment is equipped with “hardware”, then the management is “software”, this clause includes the basic requirements, tracking and measuring sources, the degree of judgment and replacement, training and use of four parts.
1.5.1 Basic requirements
The basic requirements section of the standard includes three articles. In the whole procedure of individual protective equipment, there must be a sound management system, so as to ensure that the individual protective equipment equipped with a complete range, qualified performance, reasonable distribution, management standards. Therefore, the basic requirements of the standard section of the first article provides that a sound system and distribution files should be established. These systems should at least include procurement, acceptance, storage, selection, issuance, use, obsolescence, training and so on. The second article provides for the receipt and acceptance of incoming storage and periodic inspection of state regulations. The employer should be equipped with individual protective equipment in accordance with national or industry standards, which is clearly stipulated in the “Law of the People’s Republic of China on Safety Production”, “Law of the People’s Republic of China on Prevention and Control of Occupational Diseases”, “Labor Law of the People’s Republic of China” and other regulations, and the incoming inspection is the last procedure to ensure the quality of products, so the standard makes it clear that the employer should conduct incoming inspection of individual protective equipment before it is put into storage. In addition, China for some products in its mandatory standards clearly specified in the regular inspection matters, such as GB21148 – 2020 “foot protection safety shoes” 9.2.3 provides that for electrically insulated shoes, in order to ensure safety, should be set to test the electrical properties, while it is recommended that every six months; for shoes stored for more than 24 months (calculated from the date of production), need to be tested one by one, and only meet the standard requirements before they can be sold and used. The third article mainly focuses on the response to changes in workplace hazards after being equipped with individual protective equipment. In the process of operation found that there are other hazards, the existing individual protective equipment can not meet the operational safety requirements, the need for additional with each, should immediately stop the relevant operations, in accordance with the requirements of this part with the appropriate individual protective equipment before continuing operations.

1.5.2 Traceability
Traceability system construction is the collection and recording of individual protective equipment in the production, circulation, consumption and other aspects of information, to achieve the source can be traced, the destination can be traced and other goals, to strengthen the whole process of quality and safety management and risk control of effective measures. Traceability system into individual protective equipment equipped with management, but also to implement the “General Office of the State Council on speeding up the construction of important products traceability system” (State Office issued [2015] No. 95) “around the people’s lives and property safety and public safety has a significant impact on the product, the overall planning of the national important product traceability system construction “An important initiative of the guidance.
The standard traceability section includes five articles, the first of which is the basic requirements, the fundamental provisions for the implementation of the traceability system, stipulating that the employer should purchase individual protective equipment with traceability markings on the minimum labeled packaging and transport packaging.
The second article is the requirements for manufacturers in the tracking and tracing system. The standard requires manufacturers to enter three types of information in the national tracking and tracing system before each batch of products is sold, namely: first, the manufacturer’s own information; second, the information of the products sold; and third, the information of the inspection and testing report of the product model. Among them, the inspection report provided should be noted that it is the inspection report of the product model, and not necessarily the inspection report of the batch of products. In addition, for the national tracking and tracing system, here refers to the system that can achieve the function of tracking tide source in the whole country.
The third article is the requirements for the distributors in the tracking tide source system. Because sales information is often more sensitive, therefore, the standard stipulates that dealers Before the product is sold only to enter the necessary sales information, the specific information requirements by the tracking lake source system to ensure the realization of its tracking lake source function at its own discretion.
The fourth is the requirements for tracking the source of the lake system in the inspection and testing agencies. The standard stipulates that inspection and testing agencies should be in the national tracking and tracingsystem to enter the inspection and testing report information.
Article V specifies how the employer uses the tracking and tracing system. The standard stipulates that when purchasing individual protective equipment, employers can verify the physical product information and product inspection and testing report information through the traceability mark of the product and the inspection and testing report.

1.5.3 Disposal and replacement
Judgment and replacement is an important link in the management of the whole individual protective equipment. In order to avoid the existence of certain enterprises “overdue use” of protective equipment
“continue to use after the failure of the function” and other situations, the standard provides that one of the following situations must be replaced: a) individual protective equipment is judged to be unqualified by inspection or examination: b) individual protective equipment exceeds the expiration date: c) individual protective equipment function has been invalidated: d individual protective equipment in the manual of other condemnation or replacement conditions. or replacement conditions. The standard also stipulates that the PPE that has been judged to be obsolete or replaced shall not be used again.
1.5.4 Training and Use
The training and correct use of workers is the prerequisite to ensure the correct wearing and effective protection of PPE. Relevant regulations in China attach great importance to the training of workers. For example, the “People’s Republic of China Production Safety Law” Article 28 clearly stipulates that production and operation units should educate and train employees on production safety to ensure that employees have the necessary knowledge of production safety. Without production safety education and training qualified employees, shall not be allowed to work. Occupational Disease Prevention and Control Law of the People’s Republic of China” Article 34 clearly stipulates that the employer shall provide pre-employment occupational health training and regular occupational health training during employment, popularize occupational health knowledge, urge workers to comply with occupational disease prevention and control laws, regulations, rules and operating procedures, and guide workers in the proper use of occupational disease prevention The training and use section of the standard consists of 6 parts. The training and use part of the standard includes six articles, the first of which stipulates that the use of units should develop training and assessment plans, and keep the corresponding records: the second article provides for the training period and training content of knowledge related to the equipment of individual protection: the third article is to solve the problem of some enterprises individual protective equipment “with but not wearing”, the standard provides that the wear and use of occupational health equipment is not in accordance with the provisions. Article 4 stipulates that workers should be proficient in the correct wearing and use of PPE and have the use of units to supervise the use of PPE; Article 5 stipulates the inspection of PPE before use (such as appearance inspection, suitability inspection, etc.); Article 6 stipulates how to conduct daily inspection and maintenance of PPE. Article 6 stipulates how to carry out daily inspection and maintenance of individual protective equipment, which should be in accordance with the relevant content and requirements of the product manual, instruct and supervise individual protective equipment users to carry out correct daily maintenance and pre-use inspection of individual protective equipment in use, and to designate trained and qualified personnel to be responsible for daily inspection and maintenance for those who must be in charge.
Conclusion
GB39800.1-2020 “Individual protective equipment with each specification Part 1: General Provisions” is an important technical support for China’s safety production and occupational disease prevention and control.
Technical support, is to implement the “Work Safety Law of the People’s Republic of China”, “Labor Law of the People’s Republic of China” and “Occupational Disease Prevention and Control Law of the People’s Republic of China” on individual protective equipment related requirements of the important standards, but also the follow-up of individual protective equipment and supervision and management of the important law enforcement basis, belong to the top-level standards of the individual protective equipment standard system. The development and release of the “Individual Protective Equipment Equipment Specification” series of national standards to fill the gaps in our national standards for the management of individual protective equipment, will provide the majority of practitioners with individual protective equipment management, law enforcement and supervision of the basis for our production enterprises to provide individual protective equipment guidance and equipment constraints, to protect the lives and health safety of our employees. Promote the benign development of China’s individual protective equipment industry and industry.

【Abstract】This paper systematically sorted out the classification standards of chemical proof suits for fire fighting at the present stage，and summarized the main factors，selection procedures and matters for attention that should be considered in the selection at the scene of chemical accidents.It has certain guiding significance for fire rescue teams to choose chemical proof suits correctly when handling chemical accidents in the future. 【Keywords】 fire fighting；chemical-proof suits； choice； instructions

Introduction
Chemical protective clothing is the fire rescue personnel in the disposal of gaseous, liquid hazardous chemicals and corrosive substances and oxygen deficiency site environment to implement rescue It can effectively avoid the harm caused by various dangerous substances to human body. China is a large producer of hazardous chemicals, and also a large country of hazardous chemical accidents. According to incomplete statistics, 1,314 chemical accidents occurred in 2020, including 148 accidents with more than one death, resulting in 313 deaths. General hazardous chemical accident site toxic and harmful gases, corrosive liquid flow, frame collapse, pits everywhere, such as the “3-21” Jiangsu Ringshui explosion, involving the surrounding 1.2km² of 16 enterprises and a sewage collection station martyrdom explosion, the site left 1020 risk sources, the center of the accident due to the explosion formed a diameter In the face of similar accidents, firefighters and rescue workers who do not wear various types of chemical protective clothing correctly are bound to cause erosion of chemicals on themselves.
In order to better promote the fire rescue team, especially the petrochemical accident disposal heavy formations among them, master the use of various types of chemical protective clothing. environment and taboos, improve the scientific, safety and environmental protection of accident disposal, this paper will focus on the classification of chemical protective clothing, applicable occasions, the main factors and procedures to be considered for selection and use, as well as precautions.

1.Classification of chemical protective clothing
At present, domestic and international standards involving chemical protective clothing can be divided into five categories: First, the U.S. standards, mainly refers to a series of standards of the National Fire Protection Association (NFPA), including NFPA 1991 hazardous chemical incidents with gas-tight protective clothing, NFPA 1992 chemical hazmat splash protective clothing, NFPA 1994 chemical, biological, terrorist decorated event scene protective clothing, and protective clothing according to The hazards are divided into four levels: A, B, C and D. Second, the European standard, the protective clothing according to the application scenario is divided into Type1 gas-tight protective clothing (EN943-2), Type2 non-gas-tight protective clothing (EN942-1), Type3 liquid-tight protective clothing (EN14605), Type4 spray-tight protective clothing (EN14605), Type5 protective clothing against solid particles ( ENISO13982-1), Type6 anti-mild chemical liquid splash protective clothing (EN13034), three is the 1S0 standard, 1S0 standard and the European EN standard classification remains basically the same, only in the gas-tight protective clothing less should be first aid Yang with the subdivision of protective clothing. Fourth, China’s national CB standard, China’s standards are generally adopted by the European EN standard classification, mainly divided into four categories, respectively, gas-tight protective clothing, non-gas-tight protective clothing, liquid-tight chemical protective clothing and particulate protective clothing, where the liquid-tight protective clothing is divided into jet liquid-tight protective clothing, jet liquid-tight protective clothing-ET and splash liquid-tight protective clothing. Fifth, the main firefighting GA770-2008 “firefighter chemical protective clothing” standard, the protective clothing is divided into first-class chemical protective clothing and second-class chemical protective clothing. First-class chemical protective clothing is a fully sealed one-piece structure, with positive pressure firefighting air breathing apparatus, cooling devices, firefighter call and communication equipment and other equipment with the use of gas-tight chemical protective clothing, also known as built-in heavy chemical protective clothing, the color is generally yellow. Secondary chemical protective clothing is a one-piece structure, used with external positive pressure firefighting air breathing apparatus, is a liquid-tight chemical protective clothing, also known as light chemical protective clothing, generally red.

2 Chemical protective clothing selection
Hazardous chemical accident sites are often filled with toxic and hazardous, flammable and explosive and corrosive media, fire rescue personnel are always facing the risk of poisoning, room rest, burns, corrosion and falls, etc. In the face of complex and changing site environment, we must always remember the principle of accident disposal procedures first, and firmly grasp the various The main points of the disposal of the ring, while strengthening individual protection, choose a reasonable chemical
Protective clothing.
2.1 Stopping and alerting the site
After receiving the accident alarm, the fire-fighting force should be selected according to the disaster situation. Choose to stop at a distance of 300~500m upwind, after considering the scene of fire, explosion, leakage and development trend. Explosion, leakage and development trend, the dense situation of people around the accident, the water source and surrounding building facilities and the incident weather, wind direction, wind speed and other circumstances, choose 500 ~ 1000m initial alert range. Initial stopping The initial stopping distance and alert range should be adjusted twice depending on the development of the disaster.

2.2 Determination of the danger boundary
After the parking alert is completed, a detection team should be organized to form a competent force, the team generally includes three members, two of whom are holding combustible gas detectors or toxic and hazardous gas detectors, the remaining one carrying pen and paper and markers, from upwind in an inverted triangle formation (before 2 after 1) into the accident site is responsible for concentration detection. While advancing, detecting, according to the media danger area and boundary concentration table, taking into account the wind direction and geographical environment of the scene, placing alert signs until drawing the heavy zone, medium zone, light zone and safety zone boundary range. It should be noted that the entire detection process due to changes in the environment and accident disposal process should be maintained dynamic tracking and monitoring, the specific monitoring frequency and number of times depending on the site pollution conditions.

2.3 Divide the light and heavy danger zone
According to the heavy zone, moderate zone, light zone and safety zone boundary range Delineate the corresponding accident risk zone, the general danger source near the lethal zone, the border with red and white striped warning tape mark. Hazardous source to the boundary of the severe zone Concentration range for the heavy zone, marked with a red caution tape. Boundary of severe zone Concentration range to the border of the moderate zone Concentration range for the moderate risk zone, marked with an orange caution tape. In turn, the light danger zone and the safety zone are marked with yellow and Green caution tape signs. Each alert area should be set up with entrances and exits by safety The staff should strictly implement the graded control, the implementation of real name registration, to be personal protective equipment After the inspection of personal protective equipment qualified on-site rescue personnel to enter in steps.

2.4 Choose the protection level of the site
For hazardous chemical accident leakage, fire, explosion accident site, the incident Rescue personnel should be based on the scene of the leak medium toxicity and site detection to determine the Determine the scope of the light and heavy danger zone, and fully consider the rescue personnel in the toxic environment The actual safety needs of the environment, to determine the appropriate level of protection and protection standards. standard.

Different types of chemical accidents have different characteristics and different hazards.
For the first rescuers to arrive at the scene, special attention should be paid to distinguish different disaster，The selection of chemical protective clothing should follow the general procedure of.

3.The use of chemical protective clothing
3.1 The scope of application of various types of protective clothing should be clarified
All protective clothing should avoid high temperature and open flame and should not be close to the fire. If you need to use them, you should wear fireproof chemical protective clothing or stay away from the fire. When dealing with leaks of high concentration, strong permeable gas or a large amount of organic vapor, the first The first choice is heavy-duty chemical suits. When the accident site requires direct contact with hazardous Heavy-duty chemical suits are recommended when direct contact with hazardous chemicals is required. When dealing with military toxic agents chemicals (mustard gas, sarin, phosgene, chlorine, deuterated, cyanide) Cyanide), it is recommended to choose a suit that meets the requirements of NFPA 1991-2005 Vapor Protection Kit for Hazardous Chemical Accidents” (standard for emergency rescue It is recommended to choose the special protective clothing that meets the standard of NFPA 1991-2005 “Vapor Protection Kit for Hazardous Chemical Accidents” (standard of gas-tight protective equipment for emergency rescue). This type of protective clothing face The material of this type of protective clothing adopts double-layer film composite structure, which has strong resistance to The protective clothing is made of double-layer film composite structure, which has strong resistance to the penetration of dangerous chemicals such as zirconium gas and biotoxicants. It can prevent the penetration of external gases.

3.2 Attention should be paid to the protection time limit of special chemicals in weak parts
The weak point of protection of heavy chemical protective clothing is generally in gloves, boots, face The weak points of protection of heavy duty chemical suits are generally in gloves, boots, masks and seams. When dealing with accidents, direct contact with or condensation in hazardous chemicals should be avoided or minimized. Due to the limitation of fabric material, the protective clothing For specific chemicals (such as acetone, acetonitrile, trichloromethane, ethyl acetate, tetrahydrofuran, etc.) For example, protective boots have a much lower protection time for dichloromethane. For example, the protection boots have an impermeability time of 50min for dichloromethane, while the zipper area has a resistance time of 50min for tetrahydrogen Shaanxi clear anti-permeation time of 26min, gloves to acetone, acetonitrile, acetyl The anti-permeation time of gloves to acetone, acetonitrile, ethyl acetate and tetrahydrofuran is only 9min, 22min min, 17min, 16min, before the accident treatment should confirm the chemical Before dealing with the accident, we should confirm the type of chemicals and not directly contact the dangerous chemicals or reduce the contact time. General situation In general, it is recommended that the wearing time should not exceed 60min or 60min for replacement. Direct contact with hazardous chemicals should be further shortened according to the situation.
3.3 Overprotection and improper protection should be avoided
First-level protection, compared with conventional protection, is at the expense of reducing human agility and increasing physical exertion. If conventional protection combatants can fight for 1h, while the first level of protection when the combatants fight for 20min is already tired and ready. So unnecessary over-protection, will make the combat power consumption increased exponentially, greatly affecting the effectiveness of combat. In addition, protective equipment must be targeted and used throughout, for example, protective respiratory gear can not protect the skin, not to mention the use of a protective gear to deal with all hazardous chemical disposal site. In the time period also can not only focus on the initial and ignore the end, some fire combustion products than the initial medium is more toxic, more hazardous, so protection to the whole process, as long as the core area into the personal protection must be done.
3.4 Should pay attention to the re-use of protective clothing conditions
Chemical protective clothing can generally be divided into three categories: one-time use, limited use and reusable. For single-use chemical protective clothing is generally thin in thickness, which is very easy to be worn and broken by external forces and has limited protective effect. Limited-use chemical protective clothing is mainly for storing protective clothing for future use or in cases where it is still not contaminated and damaged after use. In such cases, re-use should be thoroughly inspected and pressure tested before and after each use. Reusable chemical protective clothing should be inspected for damage after use and should be cleaned for next use according to the criteria for determining the degree of contamination and cleaning instructions provided by the factory. It should be noted that no material can be exposed to chemicals for a long time and repeatedly. Once the protective clothing has been exposed to chemicals its internal structure is bound to change, and scientific assessment should be done for re-activation.
4 Conclusion
Chemical protective clothing is the “last line of defense” for firefighters and rescuers when dealing with hazardous chemical accidents. The scientific and reasonable choice of chemical protective clothing is not only related to the success or failure of accident disposal, but also directly related to the life and health of rescuers. Therefore, in the daily training and use process, special attention should be paid to the use of chemical protective clothing, maintenance, maintenance and disposal procedures of the study to ensure that the first time in the accident disposal to make a reasonable choice and scientific response.

【Abstract】Wearing masks is the basic Way to resist Viruses after the outbreak of New Coronavirus pneumonia in 2020.
The national health and Health Committee recommends that high risk exposures such as front-line medical staff and all staff working in isolation wards choose medical masks to protect them The protective properties of medical respirators include filtration efficiency,synthetic blood penetration，and so on.The specific analysis of surface moisture resistance and tightness aims to improve the front-line staff and the public’s understanding of the protective effect and practical application of medical protective masks.
[Keywords]medicalprotective mask；protective performance； CCOVID-2019

Preface
In 2020, the new coronavirus (COVID-2019) pneumonia epidemic is raging, and its transmission is mainly through respiratory routes such as droplets, aerosols, and close contact, and proper selection and wearing of masks is an effective measure to interrupt the virus transmission through droplets. At present, the masks widely used to prevent and control the outbreak mainly include medical masks (medical protective masks, medical surgical masks, single-use medical masks) and industrial masks (KN95, N95, KF94, etc.). Why are medical masks suitable for high-risk exposed personnel but not for others, and what are the advantages of their protective properties? This paper analyzes the main protective performance indicators of medical protective masks in China according to GB/T19083-2010 “Technical Requirements for Medical Protective Masks” (GB/T19083-2010), so as to describe the protective performance and application of medical protective masks, and aims to improve the awareness of the protective effect of medical protective masks among front-line staff and people in the epidemic prevention and control work. The aim is to raise awareness of the protective effect of medical protective masks among front-line workers and the public, provide reference for the selection of masks in front-line prevention and control work, and advocate the public not to choose such masks to
At the same time, we advocate people not to choose these masks and reduce the waste of resources caused by excessive protection.

1. Medical protective masks
   Medical protective mask is a kind of airtight self-absorbing and filtering medical protective equipment that can effectively filter out fine particles in the air and block droplets, blood, body fluids and spatters.
   It is suitable for front-line medical personnel involved in various clinical medical work, especially epidemic prevention work.
   According to GB/T19083-2010 standard setting, the assessment index of medical protective masks can be summarized as appearance structure, comfort performance, safety
   The four aspects of protection performance. Appearance structure mainly assesses the basic requirements of the mask, nose clip, mask band, to ensure that the mask can be used normally: comfort performance only assesses the airflow resistance (inspiratory resistance), to ensure that the wearer breathes smoothly; safety performance assessment of flame retardancy, microorganisms, ethylene oxide residue, skin irritation, to exclude the mask fire, microbial overload, inhalation of toxic gas ethylene oxide, allergic potential; protection performance assessment of filtration efficiency, the Synthetic blood penetration, surface moisture resistance, tightness, these are also the key assessment indicators of medical protective masks.

2.Protective performance of medical protective masks
2.1 Filtration efficiency
Filtration efficiency refers to the percentage of air particles filtered by the mask under the specified testing conditions, which is both an important factor in determining the filtering and protective performance of the mask.
It is an important factor in determining the filtering and protection performance of the mask, and is also a fundamental factor in blocking viruses in the air. It is divided into bacterial filtration efficiency (BFE) and particle filtration efficiency (PFE), PFE can also be divided into oil and non-oil particle filtration efficiency. In GB19083 a 2010 standard, in the case of gas flow rate of 852L / min, the mask on non-oily particles filtration efficiency should meet the following requirements (see Table 2): Level 1 ≥ 95%; Level 2 ≥ 99%; Level 3 ≥ 99.97%. In terms of protection effect, medical protective masks required to block mostly droplets, aerosols, spatter and other non-oily particles, so there is no need to assess the BFE and oily particle filtration efficiency project. The higher the filtration efficiency of the same category of masks, the stronger the ability to filter and block microscopic particles in the air. 2020 February “New England Journal” has an article confirming that the new coronavirus diameter between 60 ~ 140nm, that is, 0.06 ~ 0.14um, testing medical protective masks over The filtering efficiency of 0.3um sodium chloride aerosol particles is used to grade the filtration efficiency of non-oil particles, and the diameter of the particles detected by the mask is larger than the diameter of the new coronavirus, but the virus cannot survive for a long time from the host cell and needs to be attached to droplets and aerosols for droplet and aerosol transmission, so the filtering efficiency of the medical protective mask plays a major role in blocking the transmission of the new coronavirus in the air Therefore, the filtration efficiency of medical protective masks plays a major role in blocking the airborne transmission of novel coronaviruses.

2.2 Anti-synthetic blood penetration performance
Anti-blood penetration performance is an important protection index of medical protective supplies. In the event of splashing, spraying or splashing of blood, body fluids, etc., this performance of the mask can reduce the level of contact between blood and the wearer, reduce the risk of blood-borne pathogens, and protect medical personnel from disease infection from blood or other body fluids. In the GB19083-2010 standard, 2mL of synthetic blood is sprayed into the mask at a pressure of 10.7kPa (80mHg) and no penetration should occur on the inside of the mask. Doctors in the process of surgery will inevitably occur in the patient’s blood, body fluids splash, wearing medical protective masks or medical surgical masks with anti-blood penetration properties can prevent blood splash to the doctor’s face resulting in occupational exposure, but in thoracic surgery or surgery with a high degree of infectiousness (such as new crown pneumonia) priority recommended to wear medical protective masks.
2.3 Surface moisture resistance
Mask surface moisture resistance refers to the mask resistance to be water wetting or penetration characteristics, generally through the wetting level to measure the surface resistance to moisture, GB/T19083-2010 standard, medical protective masks external surface wetting level is not less than GB/T4745-1997 “textile waterproof performance of the detection and evaluation of the wetting method” standard in the provisions of level 3, is now used GB/T4745-1997 in the level of moisture resistance to the mask surface moisture resistance for classification, surface moisture resistance reflects the ability of the mask to isolate the liquid, effectively reduce the risk of infectious occupational exposure to medical personnel caused by splashes of body fluids, secretions, etc., to better protect the safety of medical personnel, its nature and protective properties are similar to the resistance to synthetic blood penetration.

2.4 Fit
The GB/T19083-2010 standard stipulates that the design of medical protective masks should provide a good fit, and the total adaptation factor of the mask should be not less than 100. The mask not only affects the fit but also significantly reduces the comfort level. The shape of the mask has a great influence on the fit of the mask and the user’s face, such as the “rectangular” flat mask because the edge and the nose clip are easy to leak and the fit cannot meet the standard requirements, so it cannot be used as a medical protective mask. If the face and mask do not fit closely when wearing the mask, the outside air will enter the human respiratory tract from the gap between the mask and the face without passing through the isolation filter layer, thus significantly weakening the protective performance of the mask. The fit factor is the ratio of the concentration of the test agent outside the mask to the concentration inside the mask when the person wears the mask for the fit test, and its size reflects the fit performance of the mask, in accordance with OSHA respiratory protection standard requirements, the fit factor ≥ 100 indicates that the fit of the mask meets the protection requirements and can play a better protective role for the wearer. High-risk exposed personnel can wear medical protective masks with good fit and fit factor. The medical protective mask with good fit and suitability, the mask and its face fit closely, long time wear limit will appear face, ear strangulation and breathing difficulties and other discomfort, but so as to ensure that their exhaled and inhaled air are filtered by the filter layer, blocking the air droplets, aerosols may carry the new coronavirus.

3.Conclusion
Medical protective masks have good filtration protection for droplets, aerosols, body fluids, blood, secretions, spatter, etc., which is related to
KN95, N95, KF94 and other industrial masks do not have synthetic blood penetration resistance, surface moisture resistance; medical surgical masks do not have surface moisture resistance, tightness”; single-use medical masks do not have synthetic blood penetration resistance, particle filtration efficiency, surface moisture resistance, tightness. moisture resistance, tightness”. Therefore, medical protective masks are the highest level of protection in China, and are recommended to be worn by high-risk exposed personnel such as front-line medical personnel and all staff working in isolation wards during the epidemic of new coronavirus pneumonia. The medical protective masks are not recommended for such personnel for comfort and material considerations.

As one of the most important indexes of clothing comfort，the air permeability of woven fabric has been
widely concerned by the industry.This paper analyzes the relationship between the airpermeability of woven fabric and
Weaving process parameters，In order to explore the influence of backbeam technology on fabric air permeability, woven fabrics of the same specification were woven under different back beam heights，and the air permeability of grey fabric was tested. The relationship between air permeability and surface structure of woven fabric and back beam height were analyzed.and the regression equation between air permeability of fabric and height of back beam was obtained. The results showed that the air permeability of woven fabric is positively correlated with the height of back beam duringg weaving. The improvement effect of air permeability caused by adjusting the height of back sill can be reflected in the finished fabric by adopting appropriate finishing process.
[Keywords] air permeability ; woven fabric ; back beam height: inter yarn porositys ; fabric surface structure

1.The relationship between fabric breathability and comfort of taking
With the development of society and the improvement of people’s living standards, people’s requirements for clothing comfort are becoming higher and higher, and research shows that the important factors reflecting the comfort of clothing are: fabric insulation, moisture permeability, water permeability, breathability, etc. Breathability mainly affects the comfort of clothing from the following aspects The following aspects affect the comfort of clothing. First of all, if the fabric is easy to air permeability, it is easy to water vapor and Liquid water is also easy to permeate, so the previously discussed moisture vapor permeability and Breathability is closely related. Secondly, the heat insulation performance of the fabric mainly depends on the static air contained in the fabric, and this factor is in turn affected by the structure and yarn, so the air permeability of the fabric also has a certain relationship”. In alpine regions, fabrics with little breathability are needed to ensure their In the hot area, it needs the fabric with large air permeability to ensure its good moisture permeability and high heat dissipation performance.
Since the breathability of the fabric is closely related to the comfort of taking, therefore Each standard has higher and higher requirements for the breathability of fabrics, such as in the old national Standard GB12014-2009 “anti-static clothing”, the non-coated woven fabric The air permeability requirement is ≥ 30mm/s; in the latest national standard GB12014 a 2019 “anti-static clothing”, the air permeability of non-coated woven fabrics required
for = 50mm/s”. Due to the changes in the market and the update of the standard, Yuanfeng Textile Technology Research Company in the past, some of the thicker and heavier grammage woven fabric, the air permeability can not meet the latest standard requirements, in order to improve the woven fabric In order to improve the air permeability of woven fabrics while meeting the requirements of the new national standard, the company has improved the air permeability of fabrics. Performance has been improved, this paper mainly discusses the relationship between woven fabric breathability and back beam In order to improve the air permeability of woven fabrics and meet the requirements of the new national standard, the company has improved the air permeability of fabrics.

Theoretical analysis
2.1 Breathability measurement method
The breathability of fabric can be measured by the air permeability. The air permeability is a measure of the air flow from one side to another under specified area, pressure and time, the airflow from one side The air permeability is the speed of air flow from one side to the other under the condition of specified area, pressure and time, and the unit is (mm/s). This paper uses the air permeability test method to measure the air permeability of woven fabrics.
2.2 Woven fabric air permeability influence factors
The factors of woven fabric air permeability are divided into fiber, yarn and fabric three level. The factors influencing fiber level include fiber cross-sectional shape, fiber fineness, fiber type and fiber moisture return rate, etc. Yarn level influencing factors specifically include yarn number, yarn structure, yarn twist, etc. Fabric Level influence factors include fabric tightness, fabric tissue structure, fabric Fabric thickness, fabric geometry, etc.
2.3 Woven fabric breathability fabric level analysis
There are many factors affecting the air permeability of woven fabrics, and this paper mainly discusses the air permeability from the weaving process. This paper mainly discusses the air permeability from the weaving process, so it is not analyzed at the fiber level and yarn level. At the fabric level, air through the interwoven pores of the woven fabric at a certain flow rate. When the pore space becomes smaller, the airflow is resisted and the air permeability becomes smaller. When the pores become larger, the airflow is resisted less and the air permeability becomes larger. In the fabric, the woven fabric should be regarded as a three-dimensional structure. In order to facilitate the study, the direction of weft yarn extension is regarded as X axis, the direction of warp yarn extension is regarded as Y axis, and the direction of warp and weft yarn extension is regarded as Y axis. The direction of weft yarn extension is regarded as the X-axis, the direction of warp yarn extension is regarded as the Y-axis, and the session curvature wave height formed after warp and weft interweaving is regarded as Z-axis.
The permeability pores are mainly divided into the following two kinds: XY axis pores, Z axis pores. Pore. Among them, XY axis pore in the fabric plane to form a rectangular pore, this Pore is the main pore of the woven fabric breathable, warp and weft yarn intertwined, the Along the width and length direction to form the XY plane, warp and weft yarn interweaving to form a rectangular In the case of a certain number of yarns, the warp density and weft The greater the warp density, the greater the X-axis gap of the rectangular seam. The higher the warp density, the smaller the rectangular slit X-axis slit, and the higher the weft density, the smaller the rectangular slit Y-axis slit. The smaller the original: Z-axis pores are formed after the warp and weft yarns are interwoven, and due to the presence of flexural
The existence of wave height, warp and weft yarn in the thickness direction is not closely appressed, but there is a certain pore, the size of this pore by the fabric Tightness, on the machine process and other factors.

2.4 Analysis of the relationship between the height of the back beam and the Z-axis aperture
The height of back beam affects the tension of upper and lower warp yarns. When the height of back beam is not equal to the height of chest beam, unequal tension bobbin is formed. When high back beam is used, the upper warp yarn tension is small and the lower warp yarn tension is large, so the upper warp yarn is relatively relaxed during weft beating and it is easier to form high flexural wave, thus increasing the Z-axis aperture height and thus improving the air permeability. Theoretically, the use of a low back beam lower than the chest beam can also form unequal tension shuttles, thus enhancing the air permeability, but in normal production life, the upper machine process generally does not use a low back beam for weaving, so the effect of a low back beam on air permeability is not discussed.

Raise the rear beam to form unequal tension shuttle, the upper warp yarn flexural wave height gets increased, thus improving the gap between Z-axis yarns, as a way to increase the breathability of the fabric also cloth. The above are theoretical analysis based on production practice and test experience, the following test to verify the reasonableness and feasibility of the way.

3 Test
3.1 Test material
Test sample: The test specimen is woven fabric, using CVC60/4032S/2×32S/2100×532/1/ as the test sample. A total of 8 kinds of rear beam height level, where the rear beam height of 980mm sample for the initial level, recorded as 0mm, the remaining 7 kinds of levels in turn, each raise 10mm, to 70mm, each level to do 10 times the test, a total of 80 tests.

3.2 Test apparatus
Test sample weaving apparatus: GA731B type rapier loom, all samples using the same warp gauge repair line, the whole sizing process, on the machine process (except for the height of the rear beam), the test will be strictly controlled as a single-factor variable test.
3.3 Test test apparatus
This test uses YG461E/I digital air permeability meter-
3.4 Test method
In this test, the height of the rear beam is continuously raised from the equal tension shuttle, and the height of the rear beam is raised by 10mm each time.
when its Z-axis aperture, when the height of the rear beam is raised, its Z-axis aperture limit. In order to raise to increase 70mm, it was found that the weaving efficiency of the loom decreased, which was not conducive to production weaving, so the height of the rear beam was no longer raised.
4.Results and discussion
4.1 Significance analysis
Before data fitting, the significance of the factor on the test results should be analyzed, according to the actual situation, using a one-way test
ANOVA, the method can discuss whether a factor has a significant effect on the test results. If the factor has a higher significance on the test results, the higher the confidence of the curve fitted to the data.
For the relative back beam height h, the significance analysis of the factor relative back beam height h on fabric breathability is very significant, so the data can be fitted to the series function
Analysis, in order to get the relative back beam height and fabric breathability between the quantitative correspondence.
4.2 Fitted function analysis
The warp session curvature wave height will increase with the height of the back beam in a certain range, and the effect of raising the back beam is more obvious at first, but it will become less and less significant as the height of the back beam increases.
Beam height to enhance the effect is less and less significant, because in a certain range, you can use a variety of functions to fit the same set of data, can get the significance of the better regression equation, but combined with the theoretical analysis, it can be seen by lifting the rear beam height of the air permeability is not very large, but the lifting effect is more stable. In line with the logarithmic function characteristics: as x increases, the effect on the dependent variable y after the unit change of x decreases continuously. Therefore, the equation of this lifting method is fitted with logarithmic function regression equation will be closer to the reality.
The height of the rear beam is linearly fitted to the regression analysis, and it can be seen from the data that the relative height of the rear beam with equal tension shuttle opening is recorded as
0m, and the regression equation is obtained by fitting the data with a logarithmic function: Y=a+blnx, where a represents the air permeability under equal tension shuttle opening, blnx
represents the relationship between the height of the back beam and the air permeability, after statistics and calculation, the regression equation of the logarithmic function between the height of the back beam and the air permeability of the woven fabric is: Y=54.15+3.86 Inx.

4.3 Finished air permeability increase effect
After lifting the beam will enhance the post-blanket breathability, in actual production, some of the performance achieved in the blanket stage to enhance the performance of the woven fabric in after finishing, the enhanced performance will disappear or very insignificant. According to production practice experience, woven fabric air permeability after finishing will have a very significant decline, the reason is that the finishing process will act on the surface of the fabric and the yarn inside, directly affecting the fabric yarn ask pore space and fiber ask pore space, if the overall finishing pore rate decreases, the air permeability decreases, if the overall finishing pore rate increases, the air permeability increases, for cotton fabrics, flame retardant finishing, resin finishing, oil repellent finishing, biological finishing, coating finishing will make its air permeability decline. Oil and water repellent finishing, biological finishing, coating finishing will make its air permeability decrease. If the air permeability effect brought by lifting the rear beam can not be maintained in the rear finishing, then this method is not effective to improve the air permeability of the fabric.
Will increase, so that the gap between the warp yarns between the fabric becomes smaller, XY axis rectangular pore area becomes smaller, will inevitably lead to a decline in woven fabric breathability. In the long car finishing process, the weft density will be reduced, can better protect the fabric in the blank stage formed Z-axis pore space, thus retaining the height of the rear beam to enhance the breathability of the effect. However, because the XY-axis rectangular pores will be narrowed, the overall air permeability will still be significantly reduced. Although the air permeability of the woven fabric still decreases significantly after the rear beam height is elevated and the finishing is done1, the air permeability is elevated compared to the finished product without the elevated rear beam height, the essence of which is that the high rear beam fabric is slightly fluffier than the middle rear beam fabric surface. Although the improvement is not large, the improvement of finished air permeability is very stable after testing, which indicates that the improvement of back beam height has a non-significant but relatively stable effect on the improvement of finished air permeability.

5.Conclusion
Among the many factors affecting the air permeability of woven fabrics, the pore space between yarns is the biggest influencing factor. Breathability, after proof and test, the following conclusions.
(1) the height of the rear beam of the loom can significantly affect the air permeability of the woven fabric. The use of unequal tension shuttle opening can enhance the air permeability, the larger the unequal tension shuttle opening The larger the unequal tension shuttle opening, the better the air permeability.
(2) The effect of the rear beam height on the air permeability of woven fabric improves as the rear beam The number correspondence can be fitted by logarithmic function. The essence of this method is to increase the flexural wave of warp yarn, thus The essence of this method is to increase the flexural wave of warp yarn, thus making the yarn pore between warp and weft yarn larger.
(3) The air permeability of the woven fabric in the finishing process basically shows a significant decrease trend, after the long car finishing process, although the fabric breathability is still After the long car finishing process, the fabric air permeability still decreases, but the air permeability can be retained by changing the height of the rear beam.