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 2006 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 2003 section "410.3 Venting of Regulators.
Pressure regulators that require a vent shall have an independent vent to the outside of the building. The vent shall be designed to prevent the entry of water or foreign objects. Exception: A vent to the outside of a building 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-2003 section "1209.7.5 Venting (A) Line Gas Pressure Regulators.
(1) An independent vent to the outside 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 there is more than one regulator at a location, each regulator shall have a separate vent to the outside, 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 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 as complying with ANSI Z21.80 / CSA 6.22 Standard for Line Pressure Regulators shall 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.