Switching valve assembly for fluid motor-driven injector pump

摘要

A pump for injecting metered amounts of liquid into a line or a conduit, which includes a reciprocating pumping piston in a cylindrical chamber having an inlet and an outlet, both of which are controlled by check valves, wherein the pumping piston is driven by a pneumatic motor of the reciprocating type and having a cylinder in which is located a power piston that is suitably connected to the pumping piston. A switching valve assembly is provided for controlling a supply of power gas or air to the pneumatic motor and which responds to the movement of the pumping and power pistons for effecting reciprocal movement of the pistons.