How to tell if air compressor check valve is bad

What is a check valve? How does it help? Many people ask these questions in many forums, and if you are one of them, you are in the right place at the correct time. A check valve is designed to prevent air backflow into the inlet line whenever the tool shuts down. It is located right between the unit and the receiver tank. Contrariwise, there is an unloader valve, which allows a bleed out of the air to reduce pressure on start-up. The check valve works on a simple balancing air mechanism between the region of high pressure and region of low pressure. It integrates a header sealed when the pressure is higher on the header than the compressor. A faulty check valve will leak air at lower pressure, so how to tell if the air compressor check valve is bad is the main aim of this article.

How to tell if air compressor check valve is bad

How to Tell if Air Compressor Check Valve is Bad

There are things that you will notice if your check valve is bad. These include:

Air Leaking from the Compressor

The only time to register air deficit from your air compressor is during usage or draining the air. Under no circumstance should your compressor lose any air while not in operation. If you notice tremendous leakage from your air compressor, then most probably your check valve is faulty. The valve only displaces to release air is some amount of pressure is applied to its disc. Otherwise, it will release air when that pressure level is not reached, causing air leakage.

Unusual Noises

If your check valve is faulty, it will tend to produce unusual noises. The first action when you realize such noises is to study your check valve position. If the noise is coming between the air compressor and the air receiver tank, your check valve is the problem.

Slow Pressure Build-Up

The check valve’s work is to maintain a one-direction flow of air for the tank to build up pressure. If the compressor’s pressure is low, the pressure build-up is low, and the check valve is certainly faulty. This is because there is a reverse flow of air from the tank.

What happens to compressors when their check valves fail?

A check valve will fail due to two main reasons: too much pressure than the recommended and too much reverse flow that damages the disc. We have seen that a faulty check valve causes leakages, which make the air compressor to deliver less pressure. Furthermore, the faulty check valve can damage the whole air compressor. Let me explain how this can be possible- a faulty check valve allows a reverse flow of air, which spins the compressor backward while not in use. The backward rotation of the air compressor destroys the unit. If the valve fails while closed, pressure will increase irrepressibly, causing compressor surge.

How to Reduce the Likelihood of Check Valve Failures

Even though you cannot prevent some failures, you can improvise some means to reduce the likelihood of their happenings. The first step is to choose a suitably-sized check valve depending on the flow conditions, valve orientation, and media type. Another thing is to install proper filters to free the check valve of debris and other particles that can damage it. Besides, you can make it a routine to monitor and maintain the check valve frequently. Maintenance includes replacing damaged valves, uninstalling to check for corrosion and flushing the system.

Air Compressor Check Valve Troubleshooting

Troubles in the check valve ultimately affect the air compressor. Therefore in this section, we are going to dig into check valve troubleshooting. From the three steps above, you can identify that the check valve is faulty. That’s when you realize leakage from the air compressor, unusual noises and slow pressure build-up on the receiver tank. However, after realizing these circumstances, you should check your valve to confirm the problem.

Test for Check Valve

There are two main ports on the check valve-The intake port allows air in, and the exhaust port lets the air out. Simply blow into the intake port for the test. If you blow through the intake port and air passes with ease, then the valve is okay. If you reverse the blow through the exhaust port, no air should pass through. Contrariwise, if the valve is faulty, both intake and exhaust ports will allow passage of air.

Cleaning the Check Valve

Since air carries debris and the filter might not block all of them, some passes to the check valve. It is thus mandatory to clean your check valve regularly as a routine for maintenance. A little cleaning can solve your headache as the debris might cause malfunction. To clean the compartment requires clothes and water. Ensure you clean all the dust on the valve properly and repeat the test above to confirm if you can use the valve again or replace it.

Replacing the Check Valve

If you’ve attempted to clean the valve and it is still not functioning, you’ll have to replace it. Or if the valve is broken, you will be forced to get another one. If the disc only is broken, replace it, but it won’t last, so the best alternative is to replace the whole valve.


1.What is a check valve?

A check valve is a bulb used to prevent the backflow of air in the flow system. The valve is also termed as non-return valves. The check valves help build up pressure in the air compressor tanks, and it opens to allow air into the tank until a certain pressure is reached.

2.How does a check valve work?

The valve incorporates an internal disk that opens and closes depending on the flow line of air. It only allows a one-way flow of air and prevents backflow. The disc will start to close whenever the flow rate decreases and closes completely to prevent the reverse flow of air. The valve has an intake port that allows air in and an exhaust port that allows air out.

3.Does an air compressor need a check valve?

If an air compressor lacks a check valve, then air will flow in reverse; thus, the pressure will not build up in the tank. The air compressor requires the check valve to maintain a one-way flow direction of air. It is the non-return valve of the air compressor.

4.What does an air check valve do?

An air check valve helps the airflow of a compressor to be in one direction only. It also maintains the flow’s pressure level by allowing a certain amount of pressure of air to pass through it.

5.What is the difference between the check valve and gate valve?

A gate valve is common in a piping system, and it is an on-off switch. If the gate valve opens, air can flow in and out of the system. However, in a check valve, air only flows in one direction.

6.Do check valves fail?

Yes, they do fail from time to time. There are circumstances where we have a faulty check valve. It would be best if you made it a routine to service your check valve. If it is old, kindly replace it. The continuous use of a faulty check valve can damage the whole unit. We have detailed a troubleshooting guide above for a faulty check valve.

Final Words

An air compressor cannot operate without a check valve or with a faulty check valve. If you sense any problem, kindly follow the guideline in this article to tell if the air compressor check valve is bad. Suppose so, stop operating your air compressor and sort the troubleshooting steps above.

If you have any comments, kindly address us in the resource box below. Good luck using your air compressor.