For the doubting Thomas (no offense to actual people named Thomas), here is a bit of info to BELIEVE…
I can not believe I have to say this in the Year 2026, but:
Anhydrous Ammonia is a FLAMMABLE GAS
Look it up on any reputable SDS.
Yes, it is shipped as a non-flammable gas, but that is ONLY because of how DOT defines a flammable gas. At a facility, it MUST be respected as a CAT 2 FLAMMABLE GAS. Please refer to and memorize 1910.1200 Appendix B.2 Flammable Gases.
Understanding the history of NH3 in the refrigeration industry and its carve-out in NFPA 70, Article 500.5 Classifications of Locations, will help the naysayers BELIEVE it is a FLAMMABLE GAS. WITHOUT ADEQUATE ventilation, as defined by IIAR 2, the Mechanical/Engine Room will be a Class 1, Division 2, Group D HAZLOC. I would even argue that the area where oil pots are routinely “drained” (i.e., process opening) MAY need to be a Div 1 HAZLOC.