Reciprocating chemical pumps

摘要

Chemical pumps are disclosed in which all parts wetted by the fluid being pumped are made of fluoroplastic material, with the pumps having check valves that include floating ball members and O-rings positioned adjacent to the floating ball members. The retainer area in which the O-ring is received has a diameter that is at least about 0.01 inch larger that the diameter of the O-ring so as to allow the O-ring to move slightly. The intake and discharge ports of the pumps comprise a bore extending into the body of the pump, with a threaded counterbore formed concentric with the bore to form a flat, annular surface between the bore and the counterbore at the inner end of the counterbore. A threaded fitting is received in the counterbore, and a seal is formed by compressing an O-ring against the annular surface at the inner end of the counterbore. The head of the pump is secured to the body thereof using spring type means that either (1) continuously applies a spring force against the head to force the head into sealing engagement with the body of the pump or (2) forms an expanding spring seal between the head and the body of the pump.