The Accu-Flo^TM pump technology employs a two-position, four-way solenoid valve that has a single operator and spring return. The valve is internally air piloted for longer coil and operator life. Air pressure is utilized to fill air chambers and displace the diaphragms, but electrical impulses dictate stroke rate. When the solenoid is unpowered, the air valve piston is held by a spring to the top of the air valve body. In this position, the air supply is directed to the right side of the pump while the left air chamber is exhausted. When the solenoid is powered by electricity, air pressure is routed to the top of the air valve piston which overcomes the tension of the spring and forces the piston down. In this position, the air valve piston directs the air supply to the left side of the pump and exhausts the right side. By alternately applying and removing electrical power, the Accu-Flo^TMpump reciprocates back and forth similar to standard air-operated pumps.