METERING PUMP CONTROL SYSTEM

摘要

A control system for a metering pump used for example in delivering controlled volumes of a dosing chemical to a fluid flow. The pump has a reciprocating piston (2) mounted in a housing (1) such that fluid is drawn into the housing (1) when the piston (2) is moved in one direction and expelled from the housing when the piston (2) is moved in the other direction. The piston (2) of the pump is controlled by a double acting piston (7) and cylinder assembly (8). An electrically controlled proportional valve (14) is arranged to control the supply of pressurized fluid to the piston (7) and cylinder assembly (8) and thereby to control the reciprocation of the pump piston (2). A sensor (17) directly or indirectly monitors the position of the pump piston (2), and controller (15) controls the proportional valve (14). The controller (15) stores data representative for the desired relationship between the position of the reciprocating element and its motion and supplies control signals to the proportional valve (14) in dependence upon an output of the sensor (17) and the stored data (18) to achieve the desired relationship. Thus the metering pump (1) can be closely controlled, enabling higher flow control ranges to be achieved, accurate delivery of chemicals, and rapid response to process demands.