Screw Pump Guide


Screw pumps are a positive displacement type of design where a set of screws rotate in a 360° rotary motion within a casing.To get more news about Single Screw Pumps, you can visit hw-screwpump.com official website.

Fluid enters the inlet before being transferred to the outlet via cavities between intermeshing screws. Due to the tight clearances slip is extremely limited, and mechanical action is highly efficient.
Single Screw
This is usually another name for a progressing cavity pump where a single screw rotated by a motor rotates within a stator. This is covered in our progressing cavity pump guide.
Twin screw / quadruple screw with external Timing Gear
A set of twin screws rotate within a pump casing with screws situated side by side. Fluid is drawn by both screws at the inlet before being pushed towards the outlet in the centre or top of the casing. Twin Screws intermeshing

One screw is driven via the motor, with the other rotated by external timing gears at the opposite end of the unit. Screws can be mounted in pairs meaning up to 4 screws can be in one pump. All screws mesh together ensuring fluid travels along the screws from the inlet towards the outlet.Pumps can be driven by a motor coupled to a gearbox, or directly coupled to the head enabling it to be driven at speeds of up to 3600rpm.

The lower the viscosity of fluids being pumped, the higher speeds at which components can be rotated at. Higher viscosity fluids such as Heavy Fuel Oil, molasses, bitumen or other slow flowing viscous liquids must be handled at reduced speeds to enable fluid sufficient time to enter the pumps inlet and ensuring cavitation does not occur. Lowering rotational speed also assists with the NPSH required by pumps.
Screw pumps are known to be efficient, due to clearances within the pump being fine. A gearbox is not always required, meaning mechanical efficiency is one of the highest when compared to other pumps such as gear or vane requiring such accessories.

Due to the design of internal parts, they can operate at high speeds due to screws suffering from low inertia during fluid transfer.Units are typically fitted complete with a relief valve protecting the pump from damage should outlet pipework become blocked, limiting the pumps ability to generate excessive pressure in such cases.

Solid Handling – Models are not suitable for abrasive solid handling which can shorten screw life due to the tight clearances and abrasive affect. Coatings can be applied to reduce wear, but any hard solids >1mm can not be accommodated comfortably. Soft products such as polymerized rubber, mince, molasses, yogurt and Jams can be handled by such units without issue.