FDA and NIOSH report that reusing single use washers, like nylon or plastic, can contribute to fires. Applied recommends using Brass and Viton washers when reusing washers.

When used more than once, the Nylon ® crush gaskets require higher torque than the elastomeric sealing washers in order to seal the cylinder valve / regulator interface, and if they are used again, they require more torque with each successive use.

The cylinder valve / regulator connection is designed to be hand-tightened. If the crush gaskets are re-used, the need for increased torque may require using a wrench or other hand tool, which can deform the crush gasket and damage the cylinder valve and regulator. This can result in leakage of oxygen past the cylinder valve seat and across the nylon crush gasket. According to a forensic analysis supported by FDA and NIOSH, “flow friction” caused by this leakage of compressed oxygen across the surface of the crush gasket may produce enough thermal energy to spontaneously ignite the nylon gasket material.

Applied recommends using brass and viton ® multiple use washers because they are more resistant to fire and less susceptible to decay in oxygen enriched atmospheres. Specifically, rubber and aluminum or rubber and brass washers are not recommended because they have a much lower ignition temperature and could decay more easily in oxygen enriched atmospheres.