Pressure regulators are commonly used in the flow of pressurized liquids and gases, and are commonly referred to as pressure-regulating valves. The pressure regulator is usually spring type, and the pressure through the pipe is controlled by the preload of the spring. Pressure regulating valve is through regulation, the inlet pressure is reduced to a need for outlet pressure, and rely on the energy of the medium itself, so that the outlet pressure automatically maintain stability of the valve. From the point of view of fluid mechanics, the pressure regulating valve is a throttling element with variable local resistance, that is, by changing the throttling area, the flow rate and kinetic energy of the fluid can be changed, resulting in different pressure losses, so as to achieve the purpose of decompression. Then rely on the control and adjustment system adjustment, so that the fluctuation of valve pressure and spring force balance, so that the valve pressure in a certain error range to maintain constant.