Abstract: This paper compares the wear resistance, anti-permeability, test environment temperature and flame resistance of chemical protective suits. It is based on the American Fire Protection Association standard NFPA1991 and the European standard EN934. The main international standards; introduced the characteristics of one-time (simple) chemical protective clothing, as well as the special working environment such as closed space to introduce the requirements of fire-fighting chemical protective clothing.
1 The emergence and application of fire protective clothing
CPVC (ChemicalProtectiveVaporClothing) is derived from military nuclear and biochemical protective clothing (NBC, Nuclear Biological Clothing), which can effectively prevent the infiltration of chemicals, toxic industrial chemicals, vapors, gases, liquids and tiny particles. At present, the application of fire-fighting chemical protective clothing in the civil field such as fire protection and emergency rescue has become more and more extensive, and it has become a necessary protective equipment for the fire department to carry out fire fighting and rescue operations in the environment of chemical dangerous goods. In the process of developing fire-fighting chemical protective clothing, the advanced countries represented by the United States emphasize multi-species, specialization and matching with other protective equipment, and constantly adjust the technical indicators of chemical protective clothing to develop new products in a targeted manner.
The original intention of designing fire-fighting chemical protective clothing is to prevent the wearer's skin from directly contacting dangerous goods of different forms. Today, 8 million kinds of chemical dangerous goods are used or in contact with people in production and life! What is incompatible with the complex reality is that scientists are currently poisoning most dangerous goods directly in contact with human skin. Little is known about side effects. Therefore, it is more necessary to take effective passive protective measures to improve the protective ability of fire-fighting chemical protective clothing and ensure the safety of firefighters engaged in fire fighting and rescue work within the dangerous goods environment.
"Class A" gas-tight fire protection suits protect against the dangers of all dangerous chemicals or other dangerous substances, regardless of their state, whether they are gaseous, liquid or solid. Therefore, "Class A" airtight fire protective clothing is generally regarded as the most protective protective clothing in the world.
At present, the design and material selection of fire-fighting chemical protective suits in the world are diversified to adapt to different working environments. Experts often use the "Protective Parameters" (PF, ProtectiveFactor) to indicate the protective effect of fire-fighting chemical protective clothing; however, due to the lack of professional guidance from the health and health departments, in many cases, the fire department is still based on traditional concepts to choose chemical protective clothing. .
2 Development of fire protection chemical protective clothing standards
Due to the short use time, the standards for fire-fighting chemical protective clothing and related ancillary products and the testing methods for typeapproval are still not perfect, and it is urgent to strengthen relevant international cooperation. Prior to the 1990s, the German vfdb standard and the British BS standard were the only national standards related to fire protection suits.
In the past ten years, in the face of more and more serious terrorist attacks, industry and industry associations in various countries have gradually strengthened the formulation and preparation of product standards and testing methods, especially the American Fire Protection Association (NFPA). In recent years, a series of Technical standards and specifications for fire protective clothing, especially biochemical protective clothing, such as NFPA 1991 "Vapor Protective Clothing Standard for Dangerous Goods Emergency Disposal", NFPA 1992 "Standard for Liquid Splash Protective Clothing for Dangerous Goods Emergency Disposal", NFPA 1994 Biochemical terrorist attack protective clothing standards [2]. At the same time, the EU has also established relevant unified standards (such as EN934), which has formed two international standards for fire protection and chemical protection products represented by NFPA standards and EU standards.
3 Comparison of NFPA1991 and EN934
Through comprehensive comparison of the standard performance indicators of NFPA1991 and EN934, two of the most representative "Class A" airtight fire protection suits, most professionals believe that the NFPA standard is superior to the EU standard, and the former is easier to understand and master. The cited materials are more clear, and the definition of the scope of the standard is more clear; and the structure of EN934 is too complicated, although the standard proposes a series of alternatives for different hazardous environments, combined with the minimum protective ability of various chemical protective clothing. Program, but because the content of EN934 is too complicated, only very professional people can master and execute. Experts believe that the reason for this situation may be that the EU standards in the drafting process, through the discussion, negotiation and mutual concessions and compromises of the 15 member states, can finally reach an agreement.
3.1 wear resistance
According to NFPA 1991, fire-fighting chemical protective suits must first pass the abrasion test designed to simulate daily wear before testing for the penetration resistance of dangerous goods. EN934 has no similar regulations. Because NFPA1991 emphasizes that fire-fighting chemical protective clothing is not only used to deal with dangerous goods accidents, in the whole duty of firefighters, it is inevitable to wear and take off chemical protective clothes frequently, and chemical protective clothing will inevitably be subject to certain wear and tear. And folding. The researchers came to the first conclusion: NFPA1991 is closer to real life and more comprehensive.
At present, NFPA is modifying the test and testing methods of fire-fighting chemical protective suits to highlight practicality and adaptability and create conditions for the emergence of new protective clothing. NFPA also realized that if the standard is too harsh, it will not only directly increase the cost of development and production of protective clothing, but also affect its promotion and use. For example, when sandpaper sanding is used to detect the abrasion resistance at the seam, it cannot be said that there is any qualitative difference between the 100-damaged product and the 92-damaged product; if the standard is too harsh, the protective clothing will only become more and more Heavy, increase the labor intensity of firefighters training and work, and reduce work efficiency.
3.2 Resistance to penetration
The Permeation Test is the primary means of testing fire protection suits against chemical hazards. NFPA1991 and EN934 both set clear and clear requirements in this respect, and the NFPA1991 regulations are particularly demanding: the maximum penetration of chemicals in the chemical suits tested should not exceed 0.1 mg/cm2•min during the 60-minute test period; The requirements of EN934 are much lower: as long as the maximum penetration of chemicals in the tested chemical suit within 10 minutes does not exceed 1.0 mg/cm2•min, it is considered qualified – even for emergency use by emergency personnel. Service, the longest test time is only extended to 30 minutes.
The minimum requirement for NFPA1991 for the anti-penetration test is 60 minutes, and as long as the chemical protective suit does not have any problems during the test, the test will continue until the chemical protective suit is damaged or other problems, and the test time may be It takes 3 hours or more. In contrast, EN934 only requires a 10-minute "penetration resistance test" time, and as long as the tested chemical protective suit passes the 10-minute test, the test stops, and people can't understand whether the chemical protective suit can be used in chemical dangerous goods. How long does it work in the environment?
Experts believe that although the current understanding of the mechanism of various dangerous goods through skin contact and invading the human body is not very deep and comprehensive, it is clear that NFPA1991 pays more attention to the potential hazard of chemical dangerous goods than EN934 - this is the comparison between experts Two conclusions.
Of course, some experts believe that the NFPA 1991 "Vapor-Protective Suit" is effective in preventing the infiltration of chemical gases and vapors, as well as completely venting sweat and human body heat; and, because of the air breathing apparatus cylinder gas supply The time is usually only 1 hour, and the effective working hours of firefighters wearing steam protective clothing are only 20 to 25 minutes at a time. It is not necessary to extend the test time to 60 minutes.
3.3 Test ambient temperature
An important factor that directly affects the above-mentioned "penetration test" conclusion is that both NFPA 1991 and EN 934 impose an upper limit on the ambient temperature at the time of testing: NFPA 1991 requires that the temperature of the test environment should not exceed 27 ° C and EN 934 should not exceed 20 ° C.
Obviously, the higher the ambient temperature, the stronger the molecular activity of various chemical dangerous goods, and the stronger their penetration ability. Since the test environment temperature specified by NFPA 1991 is higher than EN934, experts believe that the performance of the "vapor protective suit" tested by NFPA 1991 is higher than that of the similar product tested only by EN934 - this is the third conclusion.
3.4 Fire test
Compared to EN934, NFPA 1991 sets a more stringent flame resistance test and a longer refractory time setting for fire protection suits; EN934 offers different options for different flame test requirements. Experts believe that although EN934 is more scientific and targeted in theory, in actual work, if you choose chemical protective clothing according to EN934, various similar options are easy to cause confusion and confusion for users - this is the fourth Conclusion.
4 preliminary conclusions
In summary, although EN934 was developed after NFPA1991, its many indicators are generally lower than NFPA1991. Although EN934 also has its own unique features, for example, it proposes a leakle test for chemical protective clothing, and NFPA1991 does not have corresponding requirements, but in general, all firefighting chemical protective clothing that passes NFPA1991 testing and product type certification. Its comprehensive performance is better than that tested by EN934. Moreover, NFPA1991 emphasizes that the type certification of fire-fighting chemical protective clothing products is not once and for all. The chemical protective clothing must also pass the annual review conducted by relevant authorities, and the annual review is not only a spot check on the key technical indicators of the products, but even includes Verification of the production process and the manufacturer's quality assurance system.
5 disposable (simple) chemical protective clothing
With the advancement of materials science, disposable suits and limited-use suits with limited use have appeared in recent years. The above products are formed by using a thin sealing film or a metal-lined foil material in a certain order and superimposed on a surface of a less ductile and porous substrate, which has the characteristics of low cost and convenient use.
Disposable chemical protective clothing and simple chemical protective clothing can be worn directly on the outside of ordinary work clothes, or you can wear one piece in the inside and outside of ordinary work clothes. However, the sealing film used in disposable (simple) chemical protective clothing is easily damaged by external force (such as impact and friction), and is also very sensitive to flame and high temperature. Moreover, it is difficult for the user to find it once with the naked eye without using professional tools. Common scratches, scratches and fine cracks in sexual (simple) chemical protective clothing may cause hidden dangers during use.
In general, the test methods for NFPA1991 and EN934 on the wear resistance of chemical protective clothing and the penetration resistance of chemical dangerous goods are also applicable to disposable (simple) chemical protective clothing. At the same time, in response to the particularity of such products, NFPA 1991 requires firefighters to wear a "flashcoverprotective suit" on the outside of the disposable (simple) chemical protective clothing to resist damage from external forces such as impact and friction; This also better protects the wearer from the flames and high temperature heat radiation. According to NFPA1991, "flash fire protective clothing" is also a necessary supporting measure to ensure that protective clothing meets the standards when performing wear resistance test and anti-penetration test.
6 new challenges
Although the current product standards and product type certification procedures for fire protective clothing have laid the foundation for the development of new personal protective equipment, there are still limitations in EN934 and NFPA1991, and restrictions on fire protective clothing in certain places and Use of the environment.
A typical example is that most of the existing fire protection suits are not suitable for working in tight confined spaces, and are also difficult and dangerous when passing through narrow passages and entrances and exits. At present, the NFPA1991-compliant "totally encapsulated type" chemical protective suit is the only fire-resistant chemical protective suit that can accommodate a full set of self-contained air breathing apparatus (SCBA), and to ensure the normal operation of the air breathing apparatus. However, such chemical protective clothing is often too large, and there is the possibility of being pierced by a sharp object, and even endangering the personal safety of the user, and is not suitable for use through a narrow entrance and exit and in an enclosed space.
Although there are already “non-capsulatedsuit†chemical gas and vapor protective clothing that are externally used in the international market and are suitable for use in enclosed spaces, so far none of the above products have passed. NFPA1991 product type certification program. The main reason is that there is no supporting self-contained air breathing apparatus product on the market that meets the requirements of NFPA1991 while obtaining the corresponding special certification.
The structure of EN934 is different from that of NFPA1991. Its technical specifications are basically lower than those of NFPA1991. There are no provisions for the protection of "non-wound" gas, vapor and solid dangerous goods.
In the process of selecting the next generation of fire-fighting chemical protective clothing, we must truly understand and understand the complexity of different specifications and product standards, product type certification procedures. In fact, with the development of protective clothing, the term "personal protective clothing" can no longer meet the needs of real work. At present, experts are integrating various personal protective equipment into a "life support system", that is, from the perspective of the system, various protective equipment necessary for firefighters to engage in fire fighting and rescue operations in dangerous goods environments, such as protective clothing, Air respirators, life alarms, etc. are organically integrated.
1 The emergence and application of fire protective clothing
CPVC (ChemicalProtectiveVaporClothing) is derived from military nuclear and biochemical protective clothing (NBC, Nuclear Biological Clothing), which can effectively prevent the infiltration of chemicals, toxic industrial chemicals, vapors, gases, liquids and tiny particles. At present, the application of fire-fighting chemical protective clothing in the civil field such as fire protection and emergency rescue has become more and more extensive, and it has become a necessary protective equipment for the fire department to carry out fire fighting and rescue operations in the environment of chemical dangerous goods. In the process of developing fire-fighting chemical protective clothing, the advanced countries represented by the United States emphasize multi-species, specialization and matching with other protective equipment, and constantly adjust the technical indicators of chemical protective clothing to develop new products in a targeted manner.
The original intention of designing fire-fighting chemical protective clothing is to prevent the wearer's skin from directly contacting dangerous goods of different forms. Today, 8 million kinds of chemical dangerous goods are used or in contact with people in production and life! What is incompatible with the complex reality is that scientists are currently poisoning most dangerous goods directly in contact with human skin. Little is known about side effects. Therefore, it is more necessary to take effective passive protective measures to improve the protective ability of fire-fighting chemical protective clothing and ensure the safety of firefighters engaged in fire fighting and rescue work within the dangerous goods environment.
"Class A" gas-tight fire protection suits protect against the dangers of all dangerous chemicals or other dangerous substances, regardless of their state, whether they are gaseous, liquid or solid. Therefore, "Class A" airtight fire protective clothing is generally regarded as the most protective protective clothing in the world.
At present, the design and material selection of fire-fighting chemical protective suits in the world are diversified to adapt to different working environments. Experts often use the "Protective Parameters" (PF, ProtectiveFactor) to indicate the protective effect of fire-fighting chemical protective clothing; however, due to the lack of professional guidance from the health and health departments, in many cases, the fire department is still based on traditional concepts to choose chemical protective clothing. .
2 Development of fire protection chemical protective clothing standards
Due to the short use time, the standards for fire-fighting chemical protective clothing and related ancillary products and the testing methods for typeapproval are still not perfect, and it is urgent to strengthen relevant international cooperation. Prior to the 1990s, the German vfdb standard and the British BS standard were the only national standards related to fire protection suits.
In the past ten years, in the face of more and more serious terrorist attacks, industry and industry associations in various countries have gradually strengthened the formulation and preparation of product standards and testing methods, especially the American Fire Protection Association (NFPA). In recent years, a series of Technical standards and specifications for fire protective clothing, especially biochemical protective clothing, such as NFPA 1991 "Vapor Protective Clothing Standard for Dangerous Goods Emergency Disposal", NFPA 1992 "Standard for Liquid Splash Protective Clothing for Dangerous Goods Emergency Disposal", NFPA 1994 Biochemical terrorist attack protective clothing standards [2]. At the same time, the EU has also established relevant unified standards (such as EN934), which has formed two international standards for fire protection and chemical protection products represented by NFPA standards and EU standards.
3 Comparison of NFPA1991 and EN934
Through comprehensive comparison of the standard performance indicators of NFPA1991 and EN934, two of the most representative "Class A" airtight fire protection suits, most professionals believe that the NFPA standard is superior to the EU standard, and the former is easier to understand and master. The cited materials are more clear, and the definition of the scope of the standard is more clear; and the structure of EN934 is too complicated, although the standard proposes a series of alternatives for different hazardous environments, combined with the minimum protective ability of various chemical protective clothing. Program, but because the content of EN934 is too complicated, only very professional people can master and execute. Experts believe that the reason for this situation may be that the EU standards in the drafting process, through the discussion, negotiation and mutual concessions and compromises of the 15 member states, can finally reach an agreement.
3.1 wear resistance
According to NFPA 1991, fire-fighting chemical protective suits must first pass the abrasion test designed to simulate daily wear before testing for the penetration resistance of dangerous goods. EN934 has no similar regulations. Because NFPA1991 emphasizes that fire-fighting chemical protective clothing is not only used to deal with dangerous goods accidents, in the whole duty of firefighters, it is inevitable to wear and take off chemical protective clothes frequently, and chemical protective clothing will inevitably be subject to certain wear and tear. And folding. The researchers came to the first conclusion: NFPA1991 is closer to real life and more comprehensive.
At present, NFPA is modifying the test and testing methods of fire-fighting chemical protective suits to highlight practicality and adaptability and create conditions for the emergence of new protective clothing. NFPA also realized that if the standard is too harsh, it will not only directly increase the cost of development and production of protective clothing, but also affect its promotion and use. For example, when sandpaper sanding is used to detect the abrasion resistance at the seam, it cannot be said that there is any qualitative difference between the 100-damaged product and the 92-damaged product; if the standard is too harsh, the protective clothing will only become more and more Heavy, increase the labor intensity of firefighters training and work, and reduce work efficiency.
3.2 Resistance to penetration
The Permeation Test is the primary means of testing fire protection suits against chemical hazards. NFPA1991 and EN934 both set clear and clear requirements in this respect, and the NFPA1991 regulations are particularly demanding: the maximum penetration of chemicals in the chemical suits tested should not exceed 0.1 mg/cm2•min during the 60-minute test period; The requirements of EN934 are much lower: as long as the maximum penetration of chemicals in the tested chemical suit within 10 minutes does not exceed 1.0 mg/cm2•min, it is considered qualified – even for emergency use by emergency personnel. Service, the longest test time is only extended to 30 minutes.
The minimum requirement for NFPA1991 for the anti-penetration test is 60 minutes, and as long as the chemical protective suit does not have any problems during the test, the test will continue until the chemical protective suit is damaged or other problems, and the test time may be It takes 3 hours or more. In contrast, EN934 only requires a 10-minute "penetration resistance test" time, and as long as the tested chemical protective suit passes the 10-minute test, the test stops, and people can't understand whether the chemical protective suit can be used in chemical dangerous goods. How long does it work in the environment?
Experts believe that although the current understanding of the mechanism of various dangerous goods through skin contact and invading the human body is not very deep and comprehensive, it is clear that NFPA1991 pays more attention to the potential hazard of chemical dangerous goods than EN934 - this is the comparison between experts Two conclusions.
Of course, some experts believe that the NFPA 1991 "Vapor-Protective Suit" is effective in preventing the infiltration of chemical gases and vapors, as well as completely venting sweat and human body heat; and, because of the air breathing apparatus cylinder gas supply The time is usually only 1 hour, and the effective working hours of firefighters wearing steam protective clothing are only 20 to 25 minutes at a time. It is not necessary to extend the test time to 60 minutes.
3.3 Test ambient temperature
An important factor that directly affects the above-mentioned "penetration test" conclusion is that both NFPA 1991 and EN 934 impose an upper limit on the ambient temperature at the time of testing: NFPA 1991 requires that the temperature of the test environment should not exceed 27 ° C and EN 934 should not exceed 20 ° C.
Obviously, the higher the ambient temperature, the stronger the molecular activity of various chemical dangerous goods, and the stronger their penetration ability. Since the test environment temperature specified by NFPA 1991 is higher than EN934, experts believe that the performance of the "vapor protective suit" tested by NFPA 1991 is higher than that of the similar product tested only by EN934 - this is the third conclusion.
3.4 Fire test
Compared to EN934, NFPA 1991 sets a more stringent flame resistance test and a longer refractory time setting for fire protection suits; EN934 offers different options for different flame test requirements. Experts believe that although EN934 is more scientific and targeted in theory, in actual work, if you choose chemical protective clothing according to EN934, various similar options are easy to cause confusion and confusion for users - this is the fourth Conclusion.
4 preliminary conclusions
In summary, although EN934 was developed after NFPA1991, its many indicators are generally lower than NFPA1991. Although EN934 also has its own unique features, for example, it proposes a leakle test for chemical protective clothing, and NFPA1991 does not have corresponding requirements, but in general, all firefighting chemical protective clothing that passes NFPA1991 testing and product type certification. Its comprehensive performance is better than that tested by EN934. Moreover, NFPA1991 emphasizes that the type certification of fire-fighting chemical protective clothing products is not once and for all. The chemical protective clothing must also pass the annual review conducted by relevant authorities, and the annual review is not only a spot check on the key technical indicators of the products, but even includes Verification of the production process and the manufacturer's quality assurance system.
5 disposable (simple) chemical protective clothing
With the advancement of materials science, disposable suits and limited-use suits with limited use have appeared in recent years. The above products are formed by using a thin sealing film or a metal-lined foil material in a certain order and superimposed on a surface of a less ductile and porous substrate, which has the characteristics of low cost and convenient use.
Disposable chemical protective clothing and simple chemical protective clothing can be worn directly on the outside of ordinary work clothes, or you can wear one piece in the inside and outside of ordinary work clothes. However, the sealing film used in disposable (simple) chemical protective clothing is easily damaged by external force (such as impact and friction), and is also very sensitive to flame and high temperature. Moreover, it is difficult for the user to find it once with the naked eye without using professional tools. Common scratches, scratches and fine cracks in sexual (simple) chemical protective clothing may cause hidden dangers during use.
In general, the test methods for NFPA1991 and EN934 on the wear resistance of chemical protective clothing and the penetration resistance of chemical dangerous goods are also applicable to disposable (simple) chemical protective clothing. At the same time, in response to the particularity of such products, NFPA 1991 requires firefighters to wear a "flashcoverprotective suit" on the outside of the disposable (simple) chemical protective clothing to resist damage from external forces such as impact and friction; This also better protects the wearer from the flames and high temperature heat radiation. According to NFPA1991, "flash fire protective clothing" is also a necessary supporting measure to ensure that protective clothing meets the standards when performing wear resistance test and anti-penetration test.
6 new challenges
Although the current product standards and product type certification procedures for fire protective clothing have laid the foundation for the development of new personal protective equipment, there are still limitations in EN934 and NFPA1991, and restrictions on fire protective clothing in certain places and Use of the environment.
A typical example is that most of the existing fire protection suits are not suitable for working in tight confined spaces, and are also difficult and dangerous when passing through narrow passages and entrances and exits. At present, the NFPA1991-compliant "totally encapsulated type" chemical protective suit is the only fire-resistant chemical protective suit that can accommodate a full set of self-contained air breathing apparatus (SCBA), and to ensure the normal operation of the air breathing apparatus. However, such chemical protective clothing is often too large, and there is the possibility of being pierced by a sharp object, and even endangering the personal safety of the user, and is not suitable for use through a narrow entrance and exit and in an enclosed space.
Although there are already “non-capsulatedsuit†chemical gas and vapor protective clothing that are externally used in the international market and are suitable for use in enclosed spaces, so far none of the above products have passed. NFPA1991 product type certification program. The main reason is that there is no supporting self-contained air breathing apparatus product on the market that meets the requirements of NFPA1991 while obtaining the corresponding special certification.
The structure of EN934 is different from that of NFPA1991. Its technical specifications are basically lower than those of NFPA1991. There are no provisions for the protection of "non-wound" gas, vapor and solid dangerous goods.
In the process of selecting the next generation of fire-fighting chemical protective clothing, we must truly understand and understand the complexity of different specifications and product standards, product type certification procedures. In fact, with the development of protective clothing, the term "personal protective clothing" can no longer meet the needs of real work. At present, experts are integrating various personal protective equipment into a "life support system", that is, from the perspective of the system, various protective equipment necessary for firefighters to engage in fire fighting and rescue operations in dangerous goods environments, such as protective clothing, Air respirators, life alarms, etc. are organically integrated.
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