Fourth, if it is a variable pump, look at its control mode. The shell number or character string on the pump body is generally the part number of each combination of pumps cast or assembled by the manufacturer, which is generally used by the manufacturer. Rather than the relevant performance of the pump itself. To understand the performance of the pump, besides the maximum working pressure and rotating speed on the pump label, we should also understand the temperature resistance and volumetric efficiency of the pump. These two points are also important parameters of pump performance index.