All-Flo ALL-FLO double diaphragm pumps are designed with service in mind. All-Flo's patented, lube-free air valve system means no oil contamination of product and hassle free operation. Also,ALL-FLO's patented air valve won't stall at slow speeds. The air side of the pump is constructed of non-metallic materials. If a diaphragm ruptures or if fluid is spilled on the pump, these vital parts are not destroyed. Non-metallic air valve components are also much less prone to air valve icing when air lines contain water.