Gas Engineering Guide

Controls and Regulators – Venting of Gas Appliance Pressure Regulators

Gas appliance pressure regulators requiring access to the atmosphere for successful operation shall be equipped with vent piping leading outdoors or, if the regulator vent is an integral part of the equipment, into the combustion chamber adjacent to a continuous pilot, unless constructed or equipped with a vent limiting means to limit the escape of gas from the vent opening in the event of diaphragm failure to not more than one (1) cubic foot per hour. (NFPA 54 9.1.19 [1]).

Vent limiting means shall be employed on listed gas appliance pressure regulators only. (NFPA 54 9.1.19 [2]).

In the case of vents leading outdoors, means shall be employed to prevent water from entering this piping and also to prevent stoppage of the vent by insects and foreign matter. (NFPA 54 9.1.19 [3]).

Under no circumstances shall a regulator be vented to the gas utilization equipment vent, chimney, or exhaust system. (NFPA 54 9.1.19 [4]).

In the case of vents entering the combustion chamber, the vent shall be located so the pilot will readily ignite the escaping gas and the heat liberated thereby will not adversely affect the normal operation of the safety shutoff system. The terminus of the vent shall be securely held in a fixed position relative to the pilot. (NFPA 54 9.1.19 [5]).

Vent lines from a gas appliance pressure regulator and bleed lines from a diaphragm type valve shall not be connected to a common manifold. None shall terminate in a positive pressure combustion chamber. (NFPA 54 9.1.19 [6]).

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