AUTOMATICALLY OPERATIVE PUMPING EQUIPMENT

摘要

An automatically operative pumping equipment comprising a pump having a fluid delivery pipe and a fluid suction pipe; an electric motor operative to drive the pump for pumping fluid, a pressure switch positioned for sensing fluid pressure in the delivery pipe and operative to control the electric motor in response to the pressure in the delivery pipe; a by-pass passage branched off from the delivery pipe and connected to the suction pipe for defining a fluid flow path from the delivery pipe back to the suction pipe; a pressure regulator connected in the by-pass passage for controlling the flow rate through the by-pass passage by sensing the fluid pressure in the delivery pipe to maintain the pressure below a value which turns the pressure switch ON; a flow rate sensor for sensing the flow rate through the delivery pipe downstream from the by-pass passage branch and for producing a pressure signal representing same; and a by-pass passage flow rate regulator responsive to a control pressure signal and connected to the flow rate sensor to receive the flow rate sensor pressure signal for opening and closing the by-pass passage in response to the pressure signal from the flow rate sensor.