CGA P-8.7-2025

Safe Location of Oxygen, Nitrogen, and Argon Gas Vents - 2nd Edition

This publication establishes criteria for determining the safe placement of oxygen, nitrogen, and argon gas vents at air separation and cryogenic liquefaction plants. It addresses the safety risks associated with oxygen-enriched and oxygen-deficient atmospheres resulting from venting operations, which have led to documented incidents impacting operational safety. Unlike previous editions that utilized the PHAST™ 6.4.2 dispersion model, this edition employs the Ventjet model, developed through a collaborative effort between the Compressed Gas Association (CGA) and the European Industrial Gases Association (EIGA), to calculate separation distances. The scope excludes flammable or toxic gas mixtures and cryogenic liquid disposal, focusing instead on non-flammable atmospheric gases. The publication provides guidance for vent elevation and separation distances under normal, upset, and emergency conditions, offering both case-specific modeling and standardized tables. While intended primarily for new plant designs, the recommendations may also be applied to assess existing installations and potential modifications.