Page 55 - Occupational Health & Safety, July/August 2019

pare? While all require between four and six challenge gases to be tested, NFPA 1991 requires all six gases to be >99 percent pure. For NFPA 1994 Class 1, the test gas concen- tration is only 1 percent in air. For Class 2, it’s only 0.035 percent. For Class 3, it is very low at 0.004 percent. While each of these NFPA standards requires tests to measure gas permeation through protective mate- rial, the actual gas challenge used is mark- edly different.
Note the last column in Table 1 labeled “breathability.” For two standards (NFPA 1992 and NFPA 1994 Class 2), breathabil- ity is an optional claim. For two others— NFPA 1994 Class 3 and NFPA 1994 Class 4—there are mandatory requirements. Both NFPA options have lower permeation barrier and/or lower liquid integrity (show- er) test requirements. As you might expect, there are usually trade-offs in protection to increase breathability. CPC thermal com- fort is clearly a concern to be considered, but it must be balanced with the primary reason the suit is being worn—namely, chemical protection.
Although six NFPA standard options for CPC use permeation to measure chemical barrier, the exposure challenges used for NFPA 1994 are fewer, less concentrated, and therefore less challenging than what is used for NFPA 1991. These differences in stan- dard chemical barrier testing requirements are important for safety professionals to consider to ensure CPC was tested against the chemical hazards (including concentra- tion level) in their hazard scenario.
Summary
When selecting CPC, the greater your knowledge of different types of suits avail- able and how they’re evaluated will improve your ability to find the best match to pro- tect from the chemical hazards of concern. Full garment tests are a good way to assess the robustness of the design, components, and the expected PPE ensemble interfaces.
The NFPA standard performance levels discussed are the minimum requirements. Nothing in any of these NFPA standards restricts the manufacturer from exceeding these minimum requirements. Therefore, if performance requirements of a suit cer- tified to a NFPA standard do not match your hazard protection needs, further in- formation may be requested from the suit manufacturer to determine whether any additional relevant testing was performed
above what NFPA required.
Susan Lovasic is Global Regulatory Affairs Manager—DuPont Personal Protection. Since 1996, her research has focused on pro- tective apparel applications for chemical, bi- ological, thermal, and fire threats. She holds four U.S. patents associated with materials used for fire/thermal protection and is an active member of the NFPA FAE-HAZ and ASTM F23 Committees.
DuPontTM SafeSPECTM (www.safespec. dupont.com) provides the most extensive permeation chemical database and offers a Product Selector tool to help you find the best
CPC, including garments certified to NFPA 1991, 1992, and 1994, for your chemicals of concern and workplace hazard scenarios.
REFERENCES
1. NFPA 1991 “Standard on Vapor-Protective Ensembles for Hazardous Materials Emergencies and CBRN Terrorism Incidents” (2016 edition)
2. NFPA 1992 “Standard on Liquid Splash-Pro- tective Ensembles and Clothing for Hazardous Materials Emergencies” (2018 edition)
3. NFPA 1994 “Standard on Protective Ensem- bles for First Responders to Hazardous Materials Emergencies and CBRN Terrorism Incidents” (2018 edition)
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