(Hcf-Gas) Refers to those inhalation agents that, because of their vapor pressure at 98. 60F (370C) and at atmospheric pressure, cannot attain flammable concentrations when mixed with air, oxygen, or mixtures of oxygen and nitrous oxide
NFPA 99 Standard for Health Care Facilities, 2002 ed. https://law.resource.org/pub/us/cfr/ibr/004/nfpa.9 9.2005.pdf, (Std: Hlth Care Fcilty - Amer) {242 NFC}