Abstract: A diaphragm for a diaphragm pressure switch used to sense paint pressure in an airless, piston-type paint spray gun includes a disc-shaped, deflectable, chemically-inert primary member and a washer-shaped, secondary, resilient member located behind the primary member. The switch includes a hollow body which connects to the spray gun to form a sensing zone therebetween. The switch body houses a spring-biased, linearly displaceable piston with a head which extends through an opening in the body. The primary member of the diaphragm has a first surface exposed to paint in the sensing zone and a second surface with a central region which contacts the piston head. High pressure in the sensing zone deflects the primary member, and deflection of the primary member displaces the piston. The chemically inert primary member withstands the chemically-corrosive effects of solvents in the paint.

Abstract: A valve to control abrasive fluids under high pressure has a plastic seat. A circular ridge peripherally formed on the valve cartridge sealingly engages the seat. A means is provided within the valve cartridge to support the seat axially and radially. The diameter and taper of the poppet match those of a mating recess in the seat.