Manually actuated pump having pliant piston

Abstract

A dispensing pump of the pressure accumulating type includes an assembly of a pump body and a separate piston member, the body including a closure cap for securing the assembly in fluid tight communication with the opening of a container of flowable product to be dispensed, a plunger/accumulator forming a variable volume pump chamber together with the piston and being reciprocable relative thereto, and a plunger head surrounding the plunger. The plunger has a vent seal for opening and closing a vent chamber defined around the piston. The closure cap is of a hard and durable material, while the separate piston is softer and more compliant which gives its lip seal good definition which avoids pump chamber leakage as it precisely conforms to the inner diameter of the plunger and to any irregularities thereof. Likewise, the plunger head is of a rigid and durable material, while the plunger is softer and more compliant so that its vent seal will better conform to the vent chamber wall, which it slidingly engages, to avoid leakage of product through the closed vent chamber. The piston has an inlet valve thereon which may be of a wide variety of types.