Fainger make Pressure reducing skids (PRS) are required to supply certain quantity of gas at operating pressure. The PRS essentially performs a safety function i.e. limit the downstream pressure up to a predetermined set point though inlet pressure varies between maximum to minimum.Incidentally the limitation of pressure in the downstream end is supported by safety devices like shut of valve, safety valve, flame arrestor etc. The pressure regulators and safety devices are powered by gas itself, so that this function does not require any external power source i.e. compressed air or any electrical supply.