Abstract: A double-diaphragm pump is designed to be molded almost entirely out of plastic and is provided with totally externally-accessible and serviceable check valves which do not require any significant disassembly of the pump itself. The pump is also fitted with a diaphragm which is formed from a uniform thickness of material and which have convolutions which are equally disposed on either side of the angle of elevation of the unstressed diaphragm. The pump is designed for mounting on top of a barrel or drum and has a set of radiused feet so as to fit snugly against the rim in an inlet pipe which fits into a bung plug having an eccentric opening such that the opening grips the inlet pipe and the plug may be rotated so as to snugly position the pump against the rim of the drum. The air valve to the pump is provided with U-cup seals in the housing.