ISO 15500-12:20 15规定了减压阀(PRV)的测试和要求，PRV是一种压缩天然气燃料系统部件，用于ISO 3833中定义的机动车辆类型。 ISO 15500-12:20 15适用于根据ISO 15403-1使用天然气的车辆（单燃料、双燃料或双燃料应用）。不适用于下列情形: a)位于蒸发器上游并包括蒸发器的液化天然气(LNG)燃料系统部件； b)燃料容器； c)固定式燃气发动机； d)容器安装硬件； e)电子燃料管理； f)加油容器。 注1应认识到，可以检查此处未具体涵盖的其他部件，以满足ISO 15500本部分的标准，并根据适当的功能测试进行测试。注2:除非另有说明，ISO 15500本部分中所有提及的压力均视为表压。 注3 ISO 15500的这一部分是基于天然气作为燃料的工作压力为20 MPa[200 bar[1]]，在15°C下稳定。可以通过按适当的系数（比率）调节压力来适应其他工作压力。例如，25 MPa（250 bar）的工作压力系统需要将压力乘以1.25。 [1]1巴=0.1 MPa=105巴；1MPa=1N/mm2。

ISO 15500-12:2015 specifies tests and requirements for the pressure relief valve (PRV), a compressed natural gas fuel system component intended for use on the types of motor vehicles defined in ISO 3833. ISO 15500-12:2015 is applicable to vehicles using natural gas in accordance with ISO 15403-1 (mono-fuel, bi-fuel, or dual-fuel applications). It is not applicable to the following: a) liquefied natural gas (LNG) fuel system components located upstream of, and including, the vaporizer; b) fuel containers; c) stationary gas engines; d) container mounting hardware; e) electronic fuel management; f) refuelling receptacles. NOTE 1 It is recognized that miscellaneous components not specifically covered herein can be examined to meet the criteria of this part of ISO 15500 and tested according to the appropriate functional tests. NOTE 2 All references to pressure in this part of ISO 15500 are to be considered gauge pressures unless otherwise specified. NOTE 3 This part of ISO 15500 is based upon a service pressure for natural gas as a fuel of 20 MPa [200 bar[1]] settled at 15 °C. Other service pressures can be accommodated by adjusting the pressure by the appropriate factor (ratio). For example, a 25 MPa (250 bar) service pressure system will require pressures to be multiplied by 1,25. [1] 1 bar = 0,1 MPa = 10⁵ Pa; 1 MPa = 1 N/mm².