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Compressed Gas Interpretation

Question asked by paul.myren on Mar 29, 2017

The interpretation of "Compressed Gas" is unclear to me. There are multiple definitions and it's unclear if my situation is just a flammable gas or compressed flammable gas.

Definition #1: Any material or mixture having, when in its container, an absolute pressure exceeding 40psi at 70oF or, regardless of pressure at 70oF, having an absolute pressure exceeding 104 psi.

Definition #2: A material, or mixture of materials, that (1) is a gas at 68oF or less at 14.7 psia of pressure, and (2) has a boiling point of 68oF or less at 14.7 psia that is either liquified, nonliquified, or in solution, except those gases that have no other health or physical hazard properties are not considered to be compressed until the pressure in the packaging exceeds 41 psia at 68oF.


We have a biogas with H2S present at 10 inches W.C.. Whats unclear to me is by definition #1 its NOT a compressed gas. Definition #2 would describe it as a compressed gas because it meets requirements 1 & 2 and is not part of the exclusion since H2S does have health hazards.  Perhaps I am over thinking this but if its a compressed gas at 10 inches W.C. our digesters need to be 75 feet from any property lines, streets, alleys, public ways, means of egress or buildings per NFPA 55 Section