Flare purge gas

Gas introduced between a flare header’s water seal and the flare tip to prevent oxygen infiltration (backflow) into the flare tip or for other safety reasons. For a flare with no water seal, the function of flare purge gas is performed by flare sweep gas and, therefore, by definition, such a flare has no flare purge gas.

ref: Elevated Flare definitions and calculation methods from 40 CFR 63 Subpart CC section 63.641