Pump control system

Claim 1

In a fluid supply apparatus: a. a fluid reservoir; b. a header having fluid inlet means, and outlet means adapted to be connected to a plurality of fluid lines each have a valve controlling fluid flow from said header; c. a plurality of fluid pumps each having a fluid inlet and a fluid outlet; d. conduit means connecting said pump inlets to said reservoir and said pump outlets to the fluid inlet means of said header and disposing said pumps in succession in a parallel fluid circuit arrangement between said reservoir and header; e. a plurality of drive motors each drivingly connected to a different one of said pumps; f. and control means for said drive motors, comprising circuitry including: 1. a plurality of control relays arranged in succession, one for each of said drive motors, each relay including a relay coil, 2. and a plurality of fluid pressure operated control switches disposed in said fluid circuit arrangement in a succession between said pumps and said header, and each connected in series with the relay coil of a respective one of said relays, the first control switch in the succession thereof being disposed to control the first pump in the succession of pumps to deliver fluid at a predetermined high maximum pressure, the others of said control switches in the succession thereof being disposed to control their respective pumps to deliver fluid at predetermined progressively lower maximum pressures, 3. each of said control relays except the last in the succession thereof including a relay operated switch connected in series with the pressure operated control switch and coil of the next succeeding relay in said succession, so that operation of each relay and its respective drive motor following the first relay in the succession thereof is dependent upon energization of each preceding relay in said succession thereof.