Home Technology The Basics of Fixed Speed Screw Compressors: How They Work

The Basics of Fixed Speed Screw Compressors: How They Work

by Vern

Screw compressors are versatile machines that have revolutionized the world of compressed air. They are widely used in many industries, including manufacturing, medical, and food processing. While different types of screw compressors are available, fixed speed screw compressors are the most common.

In this blog post, we’ll take a closer look at how these compressors work and the benefits they offer.

What is a fixed speed screw compressor?

A fixed speed screw compressor is a type of positive displacement compressor that operates at a constant speed. It consists of two rotors that rotate in opposite directions. As the rotors turn, the air is trapped between the lobes and progressively compressed towards the discharge port. The compressed air is then discharged into a receiver tank or piping system.

How does a fixed speed screw compressor work?

A fixed speed screw compressor operates at a constant speed, which means it delivers a fixed amount of compressed air. The air is compressed in a fixed volume, regardless of the demand. When the demand for compressed air decreases, the compressor continues to operate at the same speed, but the excess air is vented. When the demand for compressed air increases, the compressor cannot deliver more air and the system pressure drops.

Advantages of fixed speed screw compressors

Simple Control

Fixed speed compressors operate at a constant speed, which means their control systems are generally simpler and more straightforward than those of VSD compressors. This makes fixed speed compressors easier to use and maintain.


Fixed speed compressors tend to be less expensive than VSD compressors, making them a good choice for small businesses and industries with limited budgets.

Robust Design

Fixed speed compressors have a relatively simple mechanical design, which makes them highly durable and reliable. They are less likely to break down or suffer from mechanical issues than VSD compressors, which feature more complex systems.

Suitable for Steady Demands

Fixed speed compressors are ideal for applications with steady compressed air demands. This is because they operate at a constant speed, which means they deliver a consistent level of air pressure.

High Efficiency

While VSD compressors are generally known for their energy efficiency, fixed speed compressors can still be highly efficient when properly matched with the compressed air demand. They are also more efficient than traditional reciprocating compressors, which tend to waste more energy due to their start/stop cycles.

Where are fixed speed screw compressors used?

Fixed speed screw compressors are used in a wide range of applications, including:


They are used to power air tools, such as grinders, sanders, and drills. They are also used to run pneumatic systems, such as conveyor belts and robotic arms.

Food processing

They provide clean, oil-free air, which is essential for food processing applications.


They are used to deliver clean, oil-free air for surgical instruments and respiratory equipment.


They are used to power jackhammers, drills, and other construction tools.


In conclusion, fixed speed screw compressors are an essential component in many industries. They utilize a simple yet efficient design to deliver compressed air at a constant speed. The benefits of using these compressors include high efficiency, low maintenance costs, and simple operation. Whether you are in the manufacturing, food processing, medical or construction industry, fixed speed screw compressors offer an excellent solution for your compressed air needs. Now, click here to learn more about fixed speed screw compressors.

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