为了保证填料密封可靠的工作，冲洗水量应为泵流量的0. 5%~1%，对于叶轮无副叶片的泵，其压力p>0. 8prgH+p，对于叶轮后盖板具有副叶片的泵，Pn>0. 6prgH十p，(式中，H、p:分别为泵的扬程和泵入口压力)。
The flushing water supplied to the impeller inlet seal of slurry pump fundamentally changes the flow characteristics and angular velocity of liquid in the cavity. This angular velocity value is less than wn/2, and the larger the amount of flushing water, the more obvious the decline of angular velocity is.
The lower the circumferential velocity of the liquid in the cavity, the higher the pressure in the cavity, and the larger the amount of flushing water supplied to the cavity.
In order to prevent the solid particles from entering the impeller inlet seal and packing seal, that is to prevent the seal from wearing, the flushing water is generally supplied.
In order to ensure the reliable work of packing seal, the flushing water should be 0.5%~1% of the pump flow. For the pump without auxiliary vanes, the pressure P > 0.8prgH+p. For the pump with auxiliary vanes on the back cover of the impeller, Pn > 0.6prgH10p. (In the type, H, P: respectively, the pump head and pump inlet pressure).
In order to protect the impeller inlet side seals, the flushing water volume should be 4%~6% of the pump flow, and its head is approximately equal to the head of the flushing water supplied to the packing seal.
When the solid-liquid mixture overflows from the pressure chamber, only the solid particles with a diameter smaller than the radial clearance between the impeller rim and the guard plate (in the closed side chamber) and the solid-liquid mixture flow into the chamber. The solid particles brought along with the solid-liquid mixture from the chamber are taken away when the solid-liquid mixture overflows into the pressurized water chamber in the opposite direction. Therefore, relatively small particles participate in the wear process caused by the above-mentioned overflow. The more such particles in the solid-liquid mixture, the greater the wear strength.
The depth of particle infiltration into the cavity (in the direction of radius) is related to many factors, including the amount of flushing water. For example, when the water supply for flushing is very small, it occurs from the sealing side of the packing. When there are secondary blades on the back cover plate of the impeller, the length of solid particles penetrating into the cavity is approximately equal to R2/3. According to the impeller test with secondary blades, no wear is observed on a very small radius, but the wear is very serious on the exit radius.