Not All NFPA 1971 Gloves Are Equal
The barrier is a critical part of a fire glove. It is also a hidden part of the glove that the fire fighter can’t inspect. Since the barrier is not visible, durability is very important because all 3 glove layers (shell, barrier, lining) work together to make up the gloves thermal protection system. If the barrier fails it will allow for exposure to water, steam, chemicals and blood borne pathogens..
The NFPA standard requires all gloves to pass an Overall Liquid Integrity Test after the gloves have been exposed to a convective heat preconditioning temperature of 350F for ten minutes. Interestingly, the same NFPA standard requires all turnout materials (including the barrier) and all other glove materials (not the barrier) to pass a heat and thermal shrinkage test conducted at 500F for a period of 5 minutes. These two tests demonstrate that the polyurethane barriers break down somewhere between the temperatures of 350F and 500F and will not hold back water, chemicals or blood from penetration and also breakdown the overall thermal protection of the 3 component layup.
If the glove is a low price point, it likely contains a polyurethane barrier.
Shelby tested polyurethane barrier inserts and noticed they all failed between 302F and 374F. Only the PTFE barriers will pass the test with the higher level of preconditioning. On glove testing, the complete (whole) gloves are tested and the barrier is being insulated from the heat and on turnout testing the individual layers are tested alone. Since the barrier is a hidden component and cannot be inspected in the field, Shelby only uses PTFE barriers in all gloves. This offers the fire fighter the best level of protection before and after heat exposures. Shelby also performs a 100% leak testing as a quality check on every glove thermal liner barrier system that it manufactures.
Think about your bunkergear, have you ever seen a polyurethane barriers? This is because of durability issues. And why Shelby only offers PTFE barriers while other suppliers offer a lower performing polyurethane barrier.