Automatic control system for centrifugal pumps

Claim 1

A pressure-thermal control system regulating the on-off operation of a liquid centrifugal pump in response to external flow demand which comprises in a closed loop arrangement: a. a centrifugal pump having an inlet and outlet therein; b. a check valve at the inlet side of said pump; c. a pressure switch located at the outlet, said switch being sensitive to a preset low pressure in the pump outlet to turn on the centrifugal pump; d. a temperature-sensitive switch located at the outlet to sense the internal liquid temperature of said pump, set to a preset temperature to turn the centrifugal pump off; e. a pressure accumulator tank located at the outlet of said pump directly above the temperature switch; f. a recirculation line connecting the inlet with the outlet of said pump; one end of said recirculation line located immediately adjacent to the outlet of said pump and the other end of said recirculation line located between the check valve and inlet of said pump, said recirculation line consisting of said temperature switch and said accumulator tank, both said temperature switch and accumulator tank located immediately adjacent to the outlet of said pump with the accumulator tank located directly above said temperature switch; such that in operation when the temperature of the liquid in the pump and recirculation line rises and reaches the preset temperature, the temperature switch opens, causing pump shut-off and any new system demand will cause liquid stored in the accumulator tank to flow past temperature switch cooling said temperature switch and causing it to close and when system demand is sufficient to deplete liquid stored in accumulator tank and cause pressure to drop to preset pressure the pressure switch closes to start said pump.