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NFPA 54/ANSI Z223.1 NATIONAL FUEL GAS CODE (2012)

5.8.6 Venting.

5.8.5.1. Line Gas Pressure Regulators.

Line gas pressure regulators shall comply with the following:

  1. An independent vent to the exterior of the building, sized in accordance with the regulator manufacturer's instructions, shall be provided where the location of the regulator is such that a ruptured diaphragm will cause a hazard.
    1. Where there is more than one regulator at a location, each regulator shall have a separate vent to the outdoors, or if approved by the authority having jurisdiction, the vent lines shall be permitted to be manifolded in accordance with accepted engineering practices to minimize back pressure in the event of diaphragm failure. (See 5.9.7 for information on properly locating the vent.)
    2. Materials for vent piping shall be in accordance with section 5.6.

Exception: A regulator and vent limiting means combination listed as complying with ANSI Z21.80 / CSA 6.22, Line Pressure Regulators, shall be permitted to be used without a vent to the outdoors.

  1. The vent shall be designed to prevent the entry of water, insects, or other foreign materials that could cause blockage.
  2. The regulator vent shall terminate at least 3 ft (0.9 m) from a source of ignition.
  3. At location where regulators might be submerged during floods, a special antiflood-type breather vent fitting shall be installed, or the vent line shall be extended above the height of the expected flood waters.
  4. A regulator shall not be vented to the appliance flue or exhaust system.

Codes for Vent Limiters

Vent limiters are designed for use indoors and spaces where limiting the amount of gas escapement due to diaphragm failure is critical. Vent limiters should not be used outdoors if they are exposed to the environment.
Regulators used outdoors must be installed in accordance with one of the following national codes:

A. National Fuel Gas Code; ANSI Z223.1 / NFPA 54 2012 section "9.1.19 Venting of Gas Appliance Pressure Regulators.
Venting of gas appliance pressure regulators shall comply with the following requirements: (2) Vent limiting means shall be employed on listed appliance regulators only. (3) In the case of vents leading outdoors, means shall be employed to prevent water from entering this pipe and also to prevent blockage of vents by insects and foreign matter."

B. International Fuel Code 2011 section "410.3 Venting of Regulators.
Pressure regulators that require a vent shall have an independent vent to the outdoors. The vent shall be designed to prevent the entry of water or foreign objects. Exception: A vent to the outdoors is not required for regulators equipped with and labeled for utilization with approved vent-limiting devices installed in accordance with the manufacturer's instructions."

C. Uniform Plumbing Code IAPMO/ANSI UPCI-2012 section "1209.7.5 Venting. 1209.7.5.1 Line Gas Pressure Regulators.

Line gas pressure regulators shall be installed in accordance with the following requirements:

(1) An independent vent to the exterior of the building, sized in accordance with manufacturer's instructions, shall be provided where the location of a regulator is such that a ruptured diaphragm will cause a hazard. Where more than one regulator at a location, each regulator shall have a separate vent to the oudoors, or where approved by the Authority Having Jurisdiction, the vent lines shall be permitted to be manifolded in accordance with accepted engineering practices to minimize backpressure in the event of diaphragm failure. [See NFPA 54:5.9.7] for information of properly locating the vent.) Materials for vent pipes shall be in accordance with Section 1209.5.

Exception: A regulator and vent-limiting means combination listed in accordance with ANSI Z21.80 / CSA 6shall be permitted to be used without a vent to the outdoors.

(2) The vent shall be designed to prevent the entry of water, insects, or other foreign materials that could cause blockage."
Vent limiters will not prevent water, insects, or other foreign materials from entering the regulator.


CAN CSA B149.1 Natural Gas & Propane Gas Installation Code Canada (2011)

5.2.2 Additional requirements for pressure regulators for propane applications

5.2.2.4. When used on a system operating at 2 psig (14 kPa) or less, a line pressure regulator equipped with a leak limiting system orificed for 1 ft³/h (0.0283 m³/h) of having a specific gravity if 1.53 shall be exempt from the requirement of Clause 5.2.1.5(b).

A regulator with vent limiting means shall be installed in a ventilated space only.

5.2.3. Additional requirements for pressure regulators for natural gas applications

5.2.3.1. When used on a system operating at 2 psig (14 kPa) or less, a line pressure regulator equipped with a leak limiting system orificed for 2.5 ft³/h (0.0706 m³/h) of a specific gravity of 0.6 shall be exempt from the requirement of Clause 5.2.1.5(b).

A regulator with vent limiting means shall be installed in a ventilated space only.

5.2.3.2. For systems with inlet pressures above 2 psig (14 kPa) a pressure regulator shall be exempt from compliance with Clause 5.2.1.5(b) of this Code, provided that it is equipped to limit the escape of gas from the vent openings, even in the event of a main diaphragm failure, to less than 2.5 ft³/h (0.0706 m³/h), that it has having an overpressure protection device (OPD) set to a pressure either below 2 psig (14 kPa) or 2 times the delivery pressure on the system and certified to ANSI Z21.80/CSA 6.22.