Abmessen von flüsssigen Zusatzstoffen

摘要

Heavy duty positive-displacement pumping apparatus, e.g. for handling sludges, slurries and the like, includes a hydraulic powered ram-type main pump (10) having inlet and delivery connections (22, 24) and a positive displacement ram-type metering pump (30) also hydraulically powered. The pumps are powered and controlled from a hydraulic power unit (44) whereby an additive substance is delivered by the metering pump to the main pump in predetermined synchronization with the main pump stroke, the apparatus further including dose control means for selectively varying the volume of each dose of additive delivered by the metering pump by regulating the hydraulic power supply cycle thereto, said means including adjustable means for determining the length of the operative stroke of the motoring pump ram. A photo-electric transducer or a potentiometer provides a position signal for the ram (36) of the pump (30), the signal being used to determine stroke reversal. <IMAGE>