Self:priming pump unit - has vane pump connected between centrifugal pump inlet and outlet branches

摘要

The self-priming pump unit has a centrifugal pump with inlet and outlet branches, and a vane pump similarly equipped. The vane pump inlet branch is connected to that of the centrifugal pump by a bypass-pipe containing a jet, and its outlet branch is connected to that of the centrifugal pump downstream of a non-return valve in the latter. The two pump rotors can be keyed to the same shaft. Once priming is complete, the discharge pressure is sufficient to cause the vanes to retract, so that there is no wear on the vane pump, and there is no need for any large quantity of liquid to be held in reserve.