Experimental investigation on inner characteristics of self-priming pumps for agricultural use

The pressure and flow characteristics near the recirculation hole of self-priming pumps with outer recirculation were measured and theoretically analyzed. If the performance of the pump changes, the pressure difference between the ends of the recirculation hole will vary in the quantity and direction except a certain situation. This pressure difference causes the energy loss near the hole, therefore, it is suggested to close up the hole by its valve when the pump is running. This is very significant to further improvement of the pumps for agricultural use.