Definition(s)
Relief Gas
All gases and vapors sent to the flare tip, not including entrained air, and consisting of the sum of organic material, nitrogen, and any other gases added to the vent gas collection system, natural gas added as supplemental fuel, nitrogen added as purge gas, natural gas flowing to the flare pilots, and steam added at the flare tip.
- NOTE: Other terms used for relief gas include flared gas, vent gas, waste gas, and waste vapor.
Source: API STD 521, Pressure-relieving and Depressuring Systems, Sixth Edition, January 2014. Global Standards