What is Screw Pump and Why Do We Use Them?

10 Mar.,2025

 

What is a screw pump? - HAOSH Pump

What is a screw pump?

Screw pump is a part of the dry compressed gas transfer pump series. They are positive displacement pumps that use one or more screws to move fluid or water along the screw shaft. These screws interlock to pressurize the fluid and move it into the system. These screws engage each other and reciprocate in the cavity of the cylinder. They are often used in industrial vacuum applications, often in combination with Roots blowers, and as oil-free roughing pumps in high vacuum and ultra-high vacuum systems. Please check out the description of various pumps

You can find more information on our web, so please take a look.

How does a screw pump work?

Screw pump operates with two counter-rotating screw rotors that are carefully designed to rotate 'toward each other'. This traps the gas in the space between the rotor 'screws'. As the screws rotate, this trapped volume is reduced, which not only compresses the gas, but also moves it toward the exhaust port.

When the progressive cavity pump begins to operate, power is supplied to the drive screw via an electric motor. The drive shaft is connected to the screwdriver that drives the screwdriver.

When the drive screw starts to rotate, the driven screws also rotate, as these screws engage each other. Due to the movement of these screws, a minimum vacuum starts to be generated in the inlet section. Due to this vacuum, fluid is drawn into the pump through the inlet valve.

As the fluid enters the pump, it becomes trapped between the gaps in the 'screws'. This trapped fluid also moves with the rotation of the screw. As the screw moves, the volume of the trapped fluid decreases and the pressure of the fluid increases.

As the pressure of the fluid increases according to the desired pressure, it is discharged from the outlet valve and moved to the desired location.

When a screw pump pumps oil or other types of viscous fluids, the screw surfaces are lubricated as the fluid is pumped, so there is little or no clearance between the screws.

However, when pumping gas/water mixtures, water, or other types of light liquids, these components cannot come into contact with each other. If there is no contact, the parts will wear out quickly. Therefore, do not use a triple screw pump (where one screw drives the other two without gears) for water supply or multi-phase operation.

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To better understand how it works, please watch the following video'

Composition of the screw pump

Characteristics of screw pump

Advantages

  • These pumps are easy to maintain.
  • Progressive cavity pumps can be used for all fluids
  • It can be dried up
  • It has a compact structure
  • These pumps provide constant and non-pulsating fluid flow
  • These have a quiet operation
  • The pump can produce greater volumetric efficiency
  • High reliability
  • Self-priming capability
  • High robustness
  • The progressive cavity pump does not pump contaminants in the fluid
  • It has frictionless rotation
  • With a progressive cavity pump, you can also pump high viscosity fluids without losing flow
  • High resistance to water vapor and particles/dust
  • Very high pumping speed
  • No contamination of the pumped medium
  • Frictionless rotation ' eliminates rotor wear
  • High efficiency due to internal compression
  • Relatively low operating costs and maintenance requirements
  • Inverter operation ' easily optimized for process requirements ' resulting in high energy efficiency

Disadvantages

  • Installation costs for small industries are high.
  • The pump requires gas ballast to transfer light gases quality
  • Without gas ballast, the ultimate pressure and pumping speed of light gases (helium and hydrogen) are reduced
  • cannot be scaled down to small pumping speeds below 50 m³/h; below approx. 100 m³/h multi-stage Roots or scroll pumps are used

Application of screw pumps

Screw pump: how they work, advantages, applications

The eccentric screw pump: Design and function

"Screw pump" is short for eccentric screw pump. After the inventor, it is also known as the Moineau pump , or from English as the PCP pump (progressive or progressing cavity pump). It is one of the rotating positive displacement pumps. The pumped medium is transported from the upper tank through the hose to the spray lance.

The eccentric screw pump has two main components: on the one hand the rotor, a rotating screw, and on the other hand the stator, a cylinder in which the rotor is located.

The stator has a similar internal geometry to the rotor ,both are helical. When the rotor rotates in the stator, defined empty spaces (conveying chambers) with circumferential sealing result, thus creating a negative pressure. This in turn ensures that the eccentric screw pump is self-priming. Due to the constant movement of the rotor (in contrast to changes in direction of reciprocating pistons and thus corresponding dead centres), material conveying is low in pulsation. At the injection lance, the medium is then divided with the aid of compressed air and can be applied evenly.

Valves for limiting the delivery spaces do not exist in this pump, which means less wear. The rotor moves eccentrically, which means that the axis of rotation of the rotor does not correspond to the axis of symmetry of the complete pump. This is also where the name of the eccentric wrom pump comes from. The eccentric screw pump should not be confused with the Archimedes screw, which is also called a screw pump and is used today especially in the conveyance of solids such as bulk materials. This is a huge helix that simply pushes the conveying elements (often solids) upwards in a trough. There is no stator in which negative pressure is generated, so that this type of material conveying does not belong to the pumps, but is a constant pressure hoist. It was originally used as a water lifting device in ancient times to pump water.

Which users and which applications is the screw pump suitable for?

The screw pump is particularly recommended for craft and painting businesses that workoften and frequently with highly viscous substances. For those who regularly plaster, reinforce, fill, coat, pour, grout or backfill large areas, a mortar spraying machine offers an unbeatable advantage in terms of saving a lot of time, material and body strength.Compared to manual application, machine application is less strenuous, easier on the back and the bags or buckets have to be carried much less distance thanks to a maximum delivery height of 20 metres and a delivery radius of 40 metres. This is particularly noticeable in new multi-storey buildings or buildings that are being renovated.

Particularly in basements, industrial buildings or car parks, which consist of few but enormously large surfaces to be coated, a plaster spraying unit such as the WAGNER units with screw pump quickly pays for itself: One person sprays plaster and a second smooths it directly.

If you want to learn more, please visit our website Screw Pump.