Abstract: An improved method and apparatus for cleaning liquid-carrying hoses, and the like. A suitable cleaning solvent is passed under pressure through the hose. The pressure of the solvent delivered to the hose is measured and used to control the pressure of compressed air mixed with the solvent to maintain a turbulent flow of a predetermined mix ratio for various solvent pressures. The turbulent solvent/compressed air mixture increases scrubbing of the hose to reduce the cleaning time and the quantity of solvent required to clean the hose.

Abstract: This invention concerns a system for insuring and accurately controlling the turbulent flow of a pressurized mixture of a gas and a cleaning fluid for purging and cleaning ducts. The pressures of cleaning fluid and the gas are continuously sensed and transduced into electrical signals for controlling valves for the pressurized gas to maintain and insure its pressure at a predetermined amount relative to the pressure of said cleaning fluid, so that when the gas and fluid are mixed in a turbulator, turbulent flow is insured. The improvements of this circuit include a pressure sensor transducer for sensing the pressure of the input of the air to the turbulator and feeding it back to the main air pressure transducer for accurately maintaining a predetermined ratio between the gas and cleaning fluid pressures within less than about 1 psi in at least pressures of 150 psi. A pressure warning signal indicates when the gas and/or cleaning fluid pressure is too low to produce effective turbulent flow.

Abstract: A circuit for delivering power to a load at a predetermined voltage and current. The circuit limits the voltage and current available at the load in the event that the load becomes either detached from the circuit or short circuited to facilitate safe operation of the load in an explosive environment such as a paint spray booth. The current is limited by a constant current source and the voltage is limited either by the maximum output voltage from the constant current source or be a zener barrier circuit.

Abstract: A circuit for controlling operation of valves which supply atomization air and pattern shaping air and coating fluid to a spray gun. In response to a trigger signal, air is immediately supplied to the spray gun. After a predetermined time delay, fluid is supplied to the spray gun. Fluid continues for the remainder of the duration of the trigger signal and air is continued for a predetermined time after the trigger signal has ceased.