Screw-Type Positive Displacement Rotary Pump:
There are several variations within the design of the screw category positive displacement, rotary pump. The major differences consist of the number of intermeshing screws included, the pitch of the screws, and the common direction of fluid flow. Two general designs are the two-screw, double-flow, pump low-pitch, and the three-screw, high-pitch and double-flow pump.