(1) Regulating range: It refers to the adjustable range of pressure reducing valve output pressure P2, in this range requires the required accuracy. Regulating the pressure range and the main spring stiffness. (2) Pressure characteristics: It refers to the flow rate g is set value, due to input pressure fluctuations caused by the output pressure fluctuations. The smaller the output pressure fluctuation, the better the characteristics of the pressure reducing valve. The output pressure must be lower than the input pressure - the setting will not substantially change with the input pressure. (3) flow characteristics: It refers to the input pressure - timing, the output pressure with the output flow g changes in the holding capacity. When the flow rate g changes, the output pressure changes as small as possible. The lower the general output pressure, the smaller it fluctuates as the output flow changes.