scope:

1.1 Purpose

The availability of commercial flame arresters listed by nationally recognized testing laboratories has frequently led to the installation of these arresters in piping systems; however, the actual conditions under which these arresters will operate may be far different from the conditions under which the arresters were tested and listed by the testing laboratories. Listed arresters are normally tested under nonflowing conditions and with ignition at the open ends of pipes attached to the arresters. The testing is conducted with limited lengths of the attached pipes. Flames propagating through piping systems continuously accelerate and can reach velocities that are much higher than those at which the arresters were tested. As a result, flame arresters, whether listed or not, may not be effective when they are incorrectly applied in piping systems. Listed arresters should not be installed in piping systems unless they have been tested under conditions equivalent to those expected in the specific applications.

This publication is intended to alert industry to the limitations of flame arresters. The highly variable conditions surrounding applications of arresters may result in high flame speeds that could render the arresters ineffective.