Oberdorfer # 121 Aluminum Helical Rotor Pump

The Oberdorfer 121 is an Aluminum Pedestal Helical Rotor Pump with Buna-N Stator, Buna-N Mechanical Seal, Stainless Steel Rotor, 3/4 inch FNPT by 3/4 inch FNPT Ports, replacement pump end only without a Motor. This pump is a helical rotor progressing cavity pump. Helical rotor pumps are a sturdy and robust category of positive displacement pumps, which comprise of a helix rubber stator and a helical rotor. The turning of the Stainless Steel helical shaped rotor within the stationary rubber stator creates a progressing cavity similar to a moving piston, and the liquid is thus displaced generating a pumping action. The rotor rotating inside the stator forms cavities via which media is pumped from suction to the discharge end of the pump. The rate of flow of the liquid is usually inversely proportionate to the pressure. The pump is relatively quiet as the rotor turns inside the resilient stator and thus generates little noise. Unlike piston pumping, extremely high pressure cannot be created because the stator is made of Buna N and is flexible. Because of this flexibe stator contaminated liquids can be handled. This pump is inherently self-priming, and the close fit of the rotor within the stator permits lifting of liquid on the suction side as high as 20 feet and does not require a foot valve. High starting torque motors are recommended in order to overcome the high starting friction of the stator, and usually the pump horsepower required is oversized to the operating horsepower required. This helical rotor design demands a single rotation - clockwise when facing the pump drive shaft. Pump rotation and "in" and "out" ports are indicated on the dimension diagrams on reverse side. The pump housing and mounting bracket is made from cast aluminum, the rotor is made from stainless steel with a hard chrome plate for improved wear properties. The stator is made from molded Buna N. The mechanical seal is a carbon and ceramic rotary face for positive sealing.