Pressure Regulator Purge Instructions When using a high pressure gas cylinder, it is best to purge the regulator anytime it is placed in service. The exception would be if the cylinder is full of air. When a regulator is attached to a cylinder, a small amount of air is trapped in the regulator. This air is a contaminate and will cause errors in ... NFPA 99 mandates the continuous monitoring of purge gas during the brazing process, by means of an audible alarm, a pressure regulator and flowmeter. The A333-N2R meets these requirements. The complete unit offers an alarm with both visual and audible signals, and a combination regulator/ flowmeter. IN STOCK Purge and Pressurization Systems Also known as an air purge system , these systems purge and pressurize the protected enclosure while maintaining pressure within. This reduces the classification within the protected enclosure from a Division 1, Zone 1, 21 to Division 2, Zone 2, 22 or general-purpose area. Purging does not require pressurization. The results shown are for the number of 'T' cylinders to provide the appropriate number of volume changes at very low flow with no pressurization. Note: NEVER enter a vessel that has been purged with Nitrogen, or any other gas unless you have tested that atmosphere for proper levels of oxygen. Siphon Purging. The siphon purging process starts by filling the vessel (e.g. a large storage tank) with liquid, such as water or any other liquid compatible with the product. The purge gas is subsequently added to the vapor space of the vessel as the liquid is drained from the vessel.