Proportioning pump improvements

摘要

A proportioning pump for liquid additive metering having a housing with a diaphragm piston therein and inlet and outlet primary fluid lines to the housing and inlet and outlet valves in the housing for moving the piston up and down. A pair of additive pistons for pumping an additive liquid into the primary fluid with the additive pistons being moved by the diaphragm piston. An overcenter spring loaded connection connects the diaphragm piston to the inlet and outlet valves and a fail safe mechanism opens both the inlet and outlet valves in the event the spring in the overcenter connection fails. One of the additive pistons has an O-ring therein which acts as a seal and a check valve.