Carlisle Fire Checks are safety devices that provide protection against flashback. Flashback is the occurrence of the fire burning backwards down inside the mixed gas feed piping, or gas and/or oxygen lines. When flashback occurs, your system runs serious risk of not only damaging equipment, but also a dangerous fire/explosion hazard if the flashback were to reach a pocket of gas such as a fuel tank or manifold. The Carlisle Fire Check protects against flashback by quenching the fire. However, a Fire Check is not positive closing. The Fire Check is constructed of a hex brass housing on the C-70, C-80, and C-90 models. The C-100, C-110, C-120, and C-130 are offered in a round steel housing. The ends of the housing are threaded to a specified NPT size. Inside of the housing is a bundle of corrugated monel ribbon. The Fire Check is placed in line with the gas feed piping. When a flashback travels down the pipe and reaches the Fire Check, the fire is physically quenched by the corrugated ribbon. Since the Fire Check physically quenches the fire, the Fire Check will eventually have to be replaced, as the ribbon inside becomes unusable.