NFPA 55 Compressed Gases and Cryogenic Fluids Code does not really tell you where hazardous gases should vent in a laboratory or a pilot plant.
7.3.1.5 Vent Pipe Termination.
7.3.1.5.1 Venting of gases shall be directed to an approved location.
Approved in this sense means someone (usually the local authority having jurisdiction (AHJ) agreeing it is a safe location. But few, if any, AHJ’s want to be involved in these small operational issues. NFPA 55 does give some more guidance:
