Delavan 3120-421F SmartFLO 12-Volt Bypass/Demand Diaphragm Pump. SmartFLO series pumps combine the advantages of both bypass and demand pump styles to give you the ultimate all-in-one pump. The pump heads have both an internal bypass valve and a pressure sensing demand switch, giving you the best of bypass and demand pump styles. Pump Type: BYPASS AND DEMAND. Max. Flow: 2.2 gpm. Max. Pressure: 85 psi. Max. Draw: 8.5 amps. Max. Fluid Temperature: 140° F. Ports: 3/8" female threaded. Motor: 12V DC. Self-priming.