A pump assembly including a first subassembly and a second subassembly. The first subassembly includes a fluid conduit; an inlet fluidly coupled to the liquid reactant dispenser and the fluid conduit; an outlet fluidly coupled to a reaction chamber and the fluid conduit; and a diaphragm, defining a portion of the fluid conduit, that flexes to pump the liquid reactant from the inlet to the outlet. The diaphragm preferably includes an actuation point coupled to the diaphragm, wherein the liquid reactant is substantially contained within the first subassembly during pumping. The second subassembly is couplable to the first subassembly, and is fluidly isolated from the liquid reactant. The second subassembly includes an actuator that couples to the actuation point, wherein operation of the actuator causes pumping action.