What is Unloader Valve in an Air Compressor?

Have you ever wondered how much equipment combines to provide your air compressor a smooth start? Well, the answer to that is many. You need not neglect the most important one, yes, the unloader valve. What basically is the unloader valve in an air compressor? It is considered the most crucial part of the reciprocating air compressor. It serves the purpose of blowing off the excess air when the compressor comes to a halt. There’s more to its functionality and working. Dive in to understand it better. 

Working on Unloader Valve in an Air Compressor

The Air receiver is an important component of the air compressor and so is the piston compressor. A pipe connects two of these very important components together. As soon as the compressor comes to a halt, the pressure drops instantly to 0 psi. This is the reason for the slight sound you get to hear as soon as the compressor stops. 

A check valve is also installed in an air compressor. Its job is to ensure that the air from the tank doesn’t flow out but only from the pipe. The reason for this is that when we turn on the compressor, the motor cannot alone drive it to start. You do need enough build-up pressure in the pipes which can only be achieved by air in the tank. 

In layman’s terms, an unloader valve works by releasing the excess air that is there in the chamber specified to combustion activities. It also releases the excess air from the relative lines and pipes as soon as the motor stops. 

The position of Unloader Valve

The compressor can be either smaller units or larger ones. The smaller ones are dedicated to home-based tasks while the larger ones are used for industrial and heavy-duty tasks. Talking about the smaller units, the unloader valve is positioned inside or either on the pressure switch. It is for this reason that in order to stop the compressor, a pressure switch has to give the signal. As soon as that happens, it actuates the unloader valve as well which is mounted on its body. 

The position of the check valve is worth considering as well. It is positioned right where the discharge pipe is as it has to prevent the tank air from draining. It basically is placed between the discharge pipe and the storage tank to ensure great effectiveness and minimal discharge of air from the tank. This check valve has a small tubing attached to it. This tubing leads all the way to the unloader valve mounted on the pressure switch. The latest compressors coming with newer and advanced technology include a solenoid valve which does the same job as the unloader valve. 

On the other hand, the larger air compressors have an unloader valve which is relatively larger in size. Therefore, it cannot be mounted on the pressure switch. It is controlled through a pilot valve. Therefore, the unloader valve is placed somewhere around the compressor and is connected to the pilot valve through a wire. 

Common Issues of Unloader Valve

It is highly likely that your unloader valve starts misbehaving and doesn’t perform its job to the fullest. Having issues with the unloader valve is very common. The most common issue prevalent with the unloader valve is that it is always closed or always opened. This leads to major disturbances in an air compressor. The malfunctioning is due to the incorrect discharge of the air which is undesirable. 

In case, your unloader valve is always closed, your air compressor will experience issues with a start-up. Another thing which you will observe is the strong blow down with a sharp noise as soon as you turn off the compressor. If you have the opposite problem, i.e. the unloader valve never closes, you will always hear the noise of air leaking. This way you can observe what the real issue is and get it checked. 

Frequently Asked Questions

1. How do you know if your air compressor unloader is bad?

You can identify if your air compressor unloaded is bad through the leakage of air. This usually happens while the motor is in working condition. 

2. How does an unloader valve work?

The unloader valve works like a safety switch. It avoids building up pressure by depressurizing water

3. How does the main air compressor unloader work?

It works by closing the pilot while the compressor is in running position until the psi is at desired rating. Once, the psi is achieved, it opens up the pilot and the valve is pressurized. Therefore, the excess air is discharged into the atmosphere.