Air is used in rotary screw compressors to keep the rotors turning, and when air is compressed, it gets hot. The unloader valve releases this excess pressure so that the rotors do not overheat and so that they can continue compressing incoming air. This minimizes friction loss within the rotary screw compressor and leads to more productivity. This article will discuss the purpose of the unloader valve and how it can help improve compressor performance.

What is an unloader valve？

An unloader valve is a device used in rotary screw compressors to release excess pressure. When the compressor is running, this valve opens and allows compressed air to escape so that the rotors do not overheat. It also minimizes friction loss within the compressor, leading to increased productivity.

What benefit does an unloader valve provide to the operation?

When an unloader valve opens and releases excess pressure, it allows for continuous compression. This means that the compressor can function without stopping to release built-up heat or pressure. This leads to increased DoE (Doe Mean Time Between Failure) and decreased maintenance needs, which will also lead to a decrease in running costs.   

Types of unloader valves

There are two distinct kinds of unloader valves:

• Non-bypassing: 

A non-bypassing type of unloader valve always keeps hot compressed air inside the compressor. This can lead to dangerous pressure build-up and ultimately cause a compressor failure.

• Bypassing: 

A bypassing type of unloader valve allows the excess compressed air to escape, thus keeping it from building up within the compressor. It’s a much safer option for preventing a dangerous pressure overload.

• Other types include:

Mechanical Unloader Valves: 

These valves are similar to the diaphragm type, but they also use a spring and two levers. They can be used in continuous or non-continuous cycle machines.

Direct Air Unloader Valves:

Direct air unloader valves reduce compressor head pressure by allowing compressed air to flow directly out of the machine without passing through an evaporator. This can be useful when the compressor is not located near the receiver tank.

Electrical Unloader Valves: 

An electrical unloader valve is controlled by an outside source. This type of unloader valve allows the compressor to run at lower pressures for longer periods before shutting off. It can also help provide short interval starts and stops, preventing unnecessary wear on the compressor’s internal parts.

Pneumatic Unloader Valves:

A pneumatic unloader valve uses compressed air to open and close the valve. This can be due to changes in machine pressure, thus making it an effective safety device for continuous-duty machines that have low discharge pressures.

How do unloader valves work?

It’s a fairly simple process that only requires the flipping of two switches to open up the unloader valve.  This allows the compressed air to flow out into the atmosphere, which reduces the pressure within the compressor. This also lessens any chance of failure by reducing the heat buildup inside the compressor.

What are some advantages of an unloader valve?

Unloader valves offer several benefits to your air system, including:

• Increases compressor production and efficiency

An unloader valve helps the compressor run more efficiently by releasing any excess pressure that could otherwise damage the machine. This allows for better compression without having to stop every few minutes from releasing the pressure.

• Prevents compressor overload 

An unloader valve prevents the compressor from overloading, which can cause it to fail. By releasing the excess pressure, the unloader valve allows for continuous compression and prevents dangerous pressure build-up.

• Reduces wear on compressor parts

The constant cycling of a compressor can wear down the internal parts over time. An unloader valve can help reduce this by allowing the compressor to run at lower pressure for longer periods. This will aid in the long life of your compressor.

• Keeps machine running cooler

As a result of heat generated by compression, the compressor can be damaged over With an unloader valve, heat is dissipated, and the machine stays cooler.

• Prevents the formation of water vapor

When hot compressed air is discharged, it can cause the formation of water vapor. An unloader valve can help reduce this by allowing the compressed air to escape directly from the machine. This prevents the build-up of water vapor inside the compressor, which can lead to corrosion and damage.

Some common problems with unloader valves and their solutions:

• 1. Improper installation 

One of the most common problems with unloader valves is improper installation. It’s essential to follow the instructions carefully while installing it.

• 2. Dirty air filters 

If the air filters are dirty, it can cause the unloader valve to malfunction. It is best to change your air filters once a year.

• 3. Incorrect air pressure

When setting up the unloader valve, be sure to set it at the correct pressure. If it’s too high or low, it can cause damage to internal components.

• 4. Mechanical problems

If your unloader valve is producing an unusual amount of noise, you may have a mechanical problem with one of the internal components. You should have a technician look at it.

• 5. Computer problems

If your system is monitored by a computer, it’s possible that the controller isn’t communicating with the compressor properly. Contact your local service technician to have them check this for you.

• 6. Electrical problems

If your unloader valve isn’t opening or closing properly, it may be an electrical problem. Have an electrician examine it to see what is wrong with it.

• 7. Valve problems

Replace the unloader valve if it is not opening or closing properly. Contact the technician to get it replaced.

• 8. Broken wires

If wire connections are broken, your unloader valve may not function properly. Be sure wire connections are secure and free of corrosion or debris before using the unloader valve again.

With an unloader valve, you can run your compressor longer and save money by reducing wear on internal components. This will also help reduce any corrosive damage that could occur due to high heat or excessive cycling.

A properly functioning unloader valve is essential to the operation of your air system and ensuring the safety and well-being of everyone around it.

Get professional help if you are experiencing problems with your unloader valve. Our website contains detailed and informative information about the valve.