Diaphragm pumps are driven by compressed air. The directional air distribution valve and pilot valve - the "air end" - are located in the center section of the pump. Liquid moves through two manifolds and outer chambers of the pump - the "wet end". Generally, check valves are located at the top and bottom of each outer chamber or on a common manifold. The two outer chambers are connected by suction and discharge manifolds. Lincoln's double diaphragm self-priming design offers many advantages over other pumps.