Screw pumps are rotary, positive displacement pumps that use one or more screws to transfer fluids along an axis. An example of a screw pump is the Archimedes screw pump that is still used in the irrigation and agricultural industry. Screw pumps are very good for handeling solids and debris. The method of pumping is such that it will not tighten the emulsion by shearing it such as a centrifugal pump does. Fluid is transferred through successive contact between the housing and the screw flights from one thread to the next.
These are lower speed pumps than a centrifugal pump and typically operate between 200 and 1,000 RPM. There are many variations in the design of the screw pump. The primary differences consist of the number of screws, pitch of the screws and the general direction of fluid flow. A progressive cavity pumps is a single screw pumps with a stationary screw and a screw that moves fluid through the pump.
Due to their design wear is typically a problem If the pump is run dry or if the shaft becomes misaligned, pump failure can and will occur. Unlike centrifugal pumps, a screw pump will continue pumping as long as the motor can spin. Because of this, it is very important to protect the pump due to low flow or no flow.
- Oilfield Production Fluids
- 400-800 GPM
- 150 PSI
- 200 to 1,000 RPM