Screw Pump Type

There are three major type of screw pump exist:

1. Single rotor
2. Multiple rotor timed
3. Multiple rotor untimed

The second and third types are available in two basic arrangements, single-end and double-end. The double-end construction is probably the best known version, as it has been by far the most widely used for many years because of its relative simplicity and compactness of design.

Double end screw pump
The double end arrangement is basically two operated, single-end pumps or pump elements of the same size with a common driving rotor that has an opposed, double helix design with one casing. The fluid enters a common inlet with a split flow going to the outboard ends of the two pumping elements and is discharged from the middle or center of the pump elements.

The double end screw pump selection is usually limited to low and medium pressure applications, with 400 lb/in2 (28 bar) being a good practical limit to be used for planning purposes. However, with special design features, applications up to 1400 lb/in2 (97 bar) can be handled.