What are the SNAP conditions on the use of inert gases, which work by lowering the oxygen level?
Inert gas systems work by lowering the oxygen in a room to a level that will not sustain combustion, while remaining high enough to sustain human life. SNAP requires that the oxygen level must not fall below 10% if employees can egress the area within one minute; the oxygen level must be designed to the 12% level if it takes longer than one minute to egress the area. The CO2 level must not exceed 5%. Three inert gases are listed acceptable by SNAP: IG-01, IG-55, and IG-541. A fourth inert gas, IG-100, was proposed as an acceptable halon substitute (with use restrictions) on Feb. 18, 1999; final action on this agent is pending.
