PUMPS

摘要

A pump such as a progressive cavity pump, a gear pump or a displacement piston pump (11) comprises a housing (12) defining a working chamber (14) having an inlet (24) and an outlet (24) and a pump displacement member (16) which is relatively movable in the working chamber to displace material worked by the pump through the working chamber from the inlet to the outlet. At least a working surface of a component (16, 54, 58) of the pump which in use is in contact with material being worked in the working chamber is formed of a material such as ultra high molecular weight polyethylene which is rigid at a normal operating temperature of the component but which is fusible at a predetermined temperature greater than the normal operating temperature but no more than about 170 DEG C. Such a component includes the rotor in a progressive cavity pump, at least one of the gears in a gear pump, and the piston crown (44), the valve check balls (54 and 58) and/or the valve seats (52 and 56) in a displacement piston pump.