Abstract: An apparatus for mixing and dispensing multiple fluids utilizes two fluid reservoirs each in fluid communication with a respective pump for pumping the fluids to a mixing head, the pumps being mechanically connected to each other and adapted to pump fluids from the reservoirs at a predetermined volume ratio, and with a pressure switch provided for measuring fluid pressure to the mixing head and stopping the pumping of fluid at a predetermined maximum pressure while starting the pumping of fluid when the fluid pressure falls below the predetermined maximum pressure. A device for detecting an empty fluid reservoir is used to stop the pumping of fluids to avoid single component pumping. A mechanical torque-releasable coupling is used to disconnect a pump from the pump drive in the event of an internal pump overload.

Abstract: A multiple fluid pumping system uses two or more fluid pumps each driven by a pneumatic piston or plunger and cylinder combination whose piston top stroke and bottom stroke positions are detected by reed switches in combination with a magnet attached to the piston. The top stroke reed switches are connected in series with one side of a two position pneumatic solenoid valve while the bottom stroke reed switches are connected in series with the other side of a two position pneumatic solenoid valve. The circuit is designed to prevent one of the pistons from changing the direction of its stroke prior to the other piston reaching the end of its stroke. A further embodiment utilizes a magnet mounted on one pneumatically driven piston or plunger and a pair of reed switches mounted on the other pneumatically driven piston or plunger to prevent one piston or plunger from moving faster or slower than the other piston or plunger.

Abstract: A multiple fluid pumping system uses two or more fluid pumps each driven by a pneumatic piston or plunger and cylinder combination whose piston top stroke and bottom stroke positions are detected by reed switches in combination with a magnet attached to the piston. The top stroke reed switches are connected in series with one side of a two position pneumatic solenoid valve while the bottom stroke reed switches are connected in series with the other side of a two position penumatic solenoid valve. The circuit is designed to prevent one of the pistons from changing the direction of its stroke prior to the other piston reaching the end of its stroke. A further embodiment utilizes a magnet mounted on one pneumatically driven piston or plunger and a pair of reed switches mounted on the other penumatically driven piston or plunger to prevent one piston or plunger from moving faster or slover than the other piston or plunger.