Abstract: A liquid supply pump adapted for coupling to a reciprocable motor, particularly for pumping liquids having thermosetting properties. The pump incorporates a double-acting piston in a pumping cylinder, driven by an elongated drive shaft which projects from the top of the pump for reciprocable motion, the pump having a lower intake valve and an upper exhaust valve, and an intermediate drive shaft seal above the pumping cylinder and a liquid and air drive shaft seal proximate the point of projection of the drive shaft from the pump, wherein said two seals are spaced apart by a distance greater than the pump stroke length, and a liquid drainage path from the intermediate seal back to the pump intake region.