1.3 Screw Pump

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Definition:-

         A screw pump is a positive-displacement (PD) pumps that use one or several screws to move fluids or solids along the screw(s) axis. In its simplest form (the Archimedes' screw pump), a single screw rotates in a cylindrical cavity, thereby moving the material along the screw's spindle.

Detail:-
Screw pumps (fixed displacement) consist of two Archimedes' screws that inter mesh and are enclosed within the same chamber. These pumps are used for high flows at relatively low pressure (max 100 bars (10,000 kPa). They were used on board ships where a constant pressure hydraulic system extended through the whole ship, especially to control ball valves,but also to help drive the steering gear and other systems. The advantage of the screw pumps is the low sound level of these pumps; however, the efficiency is not high.



The major problem of screw pumps is that the hydraulic reaction force is transmitted in a direction that's axially opposed to the direction of the flow.
There are two ways to overcome this problem:

Put a thrust bearing beneath each rotor;
Create a hydraulic balance by directing a hydraulic force to a piston under the rotor.


written by:-Farhan Mustafa,
E_mail:- farhanmustafa522@gmail.com

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