| 摘要 |
<p>A rotary pump system for pumping a liquid which is delivered under pressure from a backing pump 8, in which a rotary pump 1 has a pump body which is required to be drained of liquid at times when the pump 1 is inoperative, wherein the backing pump 8 has a by-pass circuit between its inlet and outlet ports, the by-pass circuit comprising a multiphase pump 13 which has a suction inlet 14 connected to a drain point 16 on the pump 1 body and a vortex chamber 17 through which liquid passes from the pump 13 outlet to the backing pump 8 inlet, a central outlet 18 of said vortex chamber being connected to an inlet port 6 of said pump 1. This allows automatic draining of the pump 1 body when use of this pump is not required.</p> |
