Heretofore, rotary pumps of the gyratory piston type have consisted of a relatively solid and substantially cylindrical piston which gyrates around the axis of a pump chamber having a slightly larger diameter. The radial spacing or displacement volume between the outer cylindrical face of the piston and the bore of the chamber constantly changes its location as the piston moves.Balance Valves Fluid which is drawn into this displacement volume through an inlet port is caused to move about the piston and is forced out through an outlet port proximal to the inlet port. These ports are separated from each other by a vane or partition which prevents the direct passage of fluid therebetween. API Cast Steel ValvesThe vane is usually connected to the piston and as the latter gyrates, the former slides in and out of a recess located between the inlet and outlet ports. Fluidtight contact between the vane and the sidewalls of the recess is desirable but generally impossible. Some leakage of fluid ordinarily occurs between the intake and discharge portions of the displacement volume in the region of the ports, thereby reducing the efficiency of these prior pumps.

It has been found that prior arrangements frequently produce a substantially pulsating flow since the displacement volume is regularly reduced to zero in the area of the outlet port. Prior attempts to develop a pump capable of providing negligible pulsation have resulted in a double acting configuration which includes a pair of coaxial pistons mounted side by side in separate pumping chambers and operating approximately 180

2011-12-27

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