FLAME ARRESTOR - Flame arrestor shall quench flashbacks. NON-RETURN VALVE - Flame arrestor with non-return valve shall quench flashbacks & shall not allow the reverse flow of gases. TEMPERATURE SENSITIVE CUT-OFF VALVE - Flame arrestor with temperature sensitive cut-off valve shall quench flashbacks & shall stop the gas flow before the upstream gas is ignited. PRESSURE SENSITIVE CUT-OFF VALVE - Flame arrestor with pressure sensitive cut-off valve shall quench flashbacks & the pressure sensitive cut-off function shall active at each flashback. The pressure-sensitive cut-off valve shall remain closed until it is manually reset.