Chemical Protective Garments Frequently Asked Questions

View some of the most frequently asked questions DuPont receives about Chemical Protective Garments

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What is the difference between single-use, limited-use, and reusable chemical protective garments?

What is the difference between penetration and permeation? How do I know which test method to use?

Regarding permeation, what is the breakthrough time? What is a normalized breakthrough time?

Does DuPont offer any garments that would be compliant with the OSHA Bloodborne Pathogens Regulation (29 CFR 1910.1030)? What are ASTM F1670 and ASTM F1671? Does DuPont offer any garments that pass these tests?

Whose responsibility is it to select the appropriate chemical protective clothing?

 

What is the difference between single-use, limited-use, and reusable chemical protective garments?

Answer: Single-use garments are intended for one-time wear. Limited-use garments can be worn until they are damaged, altered, or contaminated. Reusable garments can be worn multiple times as long as the suits have not become damaged during use (or if so, repaired), the suits have been completely decontaminated after use, and the barrier performance of the fabric has not been compromised. Determining whether or not a reusable garment has been fully decontaminated and that the contaminants have not altered the strength or protection capabilities of the garment can be a difficult decision. DuPont chemical protective garments are limited-use garments. As long as they have not been damaged, altered, or contaminated, they have sufficient durability to be worn multiple times.

 

What is the difference between penetration and permeation? How do I know which test method to use?

Answer: In terms of  chemical protective clothing , penetration is the passage of a chemical through a pore or opening in the barrier material. Permeation is the absorption, diffusion, and desorption of a chemical through the barrier material at the molecular level.

To help you understand the difference between these two mechanisms, consider this example. Have you ever opened an old bottle of soda to find out that it was flat? There aren't any holes in the bottle. The liquid is still inside. Why is the soda flat? It's flat because the carbon dioxide that gives soda its fizz has permeated through the walls of the bottle over time. If you opened a fresh bottle of soda and did not replace the cap, the carbon dioxide would just escape out of the top of the bottle. That would be penetration.

Penetration tests are well suited for determining particle barrier in fabrics like Tyvek® and ProShield®. Some factors that influence particle penetration include the size of the particle and the size of the pores/openings in the fabric structure. The more open a fabric structure is, the more likely a particle will be able to penetrate the fabric.

Permeation tests, by comparison, are better suited for testing hazardous liquids and vapors. They are the test method of choice for Tychem® fabrics. There are many critical factors that influence permeation: the challenge chemical (i.e., concentration, temperature, surface tension, the size of the molecules, functional groups, etc.), the makeup of the barrier material, the exposure time, and several physical factors like ambient temperature and pressure, just to name a few. Because there are so many variables, DuPont has performed permeation tests on hundreds of chemicals against our Tychem® fabrics. Our  Chemical Resistance Database  will help you make more informed decisions about protective clothing.

 

Regarding permeation, what is the breakthrough time? What is a normalized breakthrough time?

Answer: In permeation testing, the breakthrough time is the length of time it takes for a challenge chemical to permeate the barrier fabric being tested. It is measured from the point of initial contact of the challenge chemical with the outside surface of the test fabric to the time that the challenge chemical is detected on the inside of the fabric. Sensitive analytical equipment is often used to measure the amount of chemical permeating the fabric.

Normalized, sometimes called "standardized," breakthrough time is a measure of the elapsed time from initial contact with the challenge chemical until the chemical permeates the fabric at a rate of 0.1 ug/cm2/min. This is defined in ASTM F739 test method. Normalized breakthrough times eliminate biased results due to differences in the sensitivity of the detection equipment and are thus the industry standard measure of breakthrough times. DuPont reports normalized breakthrough times for permeation data.

 

Does DuPont offer any garments that would be compliant with the OSHA Bloodborne Pathogens Regulation (29 CFR 1910.1030)? What are ASTM F1670 and ASTM F1671? Does DuPont offer any garments that pass these tests?

Answer: Tyvek® and all Tychem® garments could be considered for use as protection against blood and bloodborne pathogens per OSHA 29 CFR 1910.1030.

ASTM F1670 is a synthetic blood penetration test and ASTM F1671 is a viral penetration test. Tychem® QC, Tychem® CPF3, Tychem® ThermoPro, Tychem® BR, Tychem® LV, and Tychem® TK fabrics and taped seams have been tested and pass ASTM F1670 and F1671.

Read about these test methods as well as OSHA's Bloodborne Pathogens Rule in our technical paper  Protective Clothing and Bloodborne Pathogens: What you need to Know

To find a garment that will help provide protection against blood and/or bodily fluids, please try the  SafeSPEC™ 2.0 Selector Tools.

 

Whose responsibility is it to select the appropriate chemical protective clothing?

Answer: In the USA, OSHA 29 CFR 1910.132 states that it is the responsibility of the employer to:

  • Perform a hazard assessment
  • Select PPE and inform employees
  • Fit and train employees on use, care, and service life of PPE
  • Verify training and audit compliance
  • Retrain employees as necessary

"Responsibility in selecting appropriate protective clothing should be vested in a specific individual that is trained in both chemical hazards and protective clothing use such as a safety officer or industrial hygienist."
Reference: OSHA Technical Manual, Section VIII, Chapter 1, Chemical Protective Clothing, V.