Abstract: A proportioning pump with tandem diaphragm pumps each having a pumpage chamber connected with a source of supply and a mixer and dispensing nozzle, a piston pump for operating each of the diaphragm pumps, a common eccentric drive for the pistons of the piston pumps, the piston pumps having cylinder wall sleeves extending into the hydraulic fluid reservoir, the sleeves having refill ports therethrough communicating between the pump chamber and the reservoir, one of the sleeves being longitudinally adjustable, a double threaded rotary control for the longitudinal adjustable cylinder wall sleeve, bypass pressure relief valves and passages for the hydraulic fluid from the pump chambers returning fluid to the reservoir in the event of excessive pressure, and the pump motor having a variable speed drive for widely varying the speed of the pump.

Abstract: Method and apparatus for guarding a spray tip (36) of a spray gun (10). A tip guard (20) is suitable for being connected to the gun (10) and the tip guard (20) includes an axially extending portion (34) which defines a tip guard cavity (32). The tip guard cavity (32) is in fluid communication with the liquid carrying passageways within the gun (10). Tip guard cavity (32) also extends axially downstream of the orifice (38) of the spray tip (36) whereby if the axially extending portion (34) is dangerously shortened, the tip guard cavity (32) will be exposed to the atmosphere to relieve the pressure within the spray tip cavity (46) immediately adjacent to the upstream end of the spray tip orifice (38). The velocity pressure generated by the gun (10) is thereby reduced to a level which is substantially safe.