A vent limiting orifice or device when used with Maxitrol regulators does not release or relieve gas into the environment during normal operation. Vent limiters are designed for use indoors and in 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. 13A15 Vent Protector is available for outdoor use when vent protection is required.