Self-priming system for pumps

Claim 1

In a self-priming pump system comprising a pump having an outlet and an inlet, a suction well defining a cavity at least partially below said inlet, suction line means for introducing liquid to be pumped into said cavity to a level including the top of the inlet, conduit means positioned in said cavity with one end terminating below said inlet adjacent the bottom of said cavity and with its other end connected to said inlet, reservoir means having an upstream end and a downstream end, said upstream end of said reservoir means connected to said outlet of said pump, a one-way check valve located at said downstream end of said reservoir means enabling downstream fluid movement only, drain means interconnecting said cavity and said reservoir means, repriming valve means positioned upstream from said check valve and mutually cooperating with said reservoir means and said drain means to return liquid in said reservoir means to said cavity via said drain means in response to a reduction in liquid flow from said pump, an air relief pipe connected from the top of said cavity to said reservoir means adjacent the upstream side of said check valve, and a second one-way check valve provided in said air relief pipe enabling fluid movement only in a direction towards said reservoir means, the improvement wherein the drain means includes a tee-connection positioned in a lower portion of the reservoir means and pipe means for interconnecting said tee-connection and the cavity, the repriming valve means being positioned in said pipe means; wherein the reservoir means includes venturi means for defining a flow restriction therein; and wherein the system includes adjustable control means for selectively actuating the repriming valve means in response to variations in fluid movement through the reservoir means, said control means including: first means for sensing and generating a first signal representative of the pressure within said flow restriction; second means for sensing and generating a second signal representative of the pressure within the reservoir means at a position spaced from said flow restriction; and controller means for comparing said first and said second signals and for opening the repriming valve when the difference between the signals falls to a predetermined point, the predetermined point being adjustable so that the system responds to the characteristics liquid being pumped.