Air Compressor Check Valve Troubleshooting: How to Identify, Test and Fix

The check valve is an important part of an air compressor. It ensures a one-directional flow of air so that your compressor can build pressure.

However, problems in the check valve cause troubles for an air compressor. So, today I am going to provide an article on air compressor check valve troubleshooting, to help you get over the problems.

Identification of a Faulty Check Valve in Air Compressor

There are a few things that you can notice if you have a damaged check valve in your compressor. These are –

Air Leaking from the Compressor

When you are not working with the compressor, air should not leak from the tank of the compressor. However, if you find the air is leaking, this could easily mean that there is a problem in the check valve.

Usually, check valves do not open until a certain pressure is given on the disc of the valve. However, if there is a problem with the check valve, then it can open without reaching that pressure level. This causes air to leak from the tank.

Credit: Flickr

Slow Pressure Build-Up

If you find that the pressure coming out from the compressor is not high enough, then there is something wrong with the check valve.

Check valves are there to stop the reverse flow of air and so the pressure stays constant in one direction only. When there is a reverse flow, the pressure that the compressor was supposed to give, becomes less. In this case, your compressor will take more time to build up the pressure.

Unusual Noises

Another sign of a faulty air compressor inline check valve is that it will make unusual noises. If you hear such noises, you should look up in the area where the check valve is located. If the noise is coming out from there, then there is definitely something wrong with the check valve.

How to Test Air Compressor Check Valve

The signs that I have talked about above, cannot surely imply that the check valve has something wrong with it. But if you find these signs then you should test your check valve to see if it’s okay or not.

The test is really simple. But for the test, you should know that there are two main ports of a check valve.

Image shows Diagram of Air Compressor Check Valve
Credit: Wikimedia Commons
  • Port 1: It is the intake port which takes the air in.
  • Port 2: It is the exhaust port that lets the air out.

So, you have to simply blow through the ports to test the check valve. For a fine check valve, when you blow through the intake port, air should easily pass. For the exhaust port, no matter how hard you blow, air should not pass.

However, for the faulty check valve, the intake port will give you the same result. But the exhaust port will also let some air go through it. This is how you can ensure if the check valve has any problem or not.

Cause of Check Valve Problems

A check valve can get damaged for certain reasons. But there are mainly two reasons. These are –

  1. When the air has too much pressure while flowing through the check valve, the pressure can cause damage to the valve.
  2. If there is a reverse flow occurring, the job of the check valve is to stop that flow. But if the reverse flow happens more often, then it damages the valves disc.

Air Compressor Check Valve Troubleshooting

Now it’s time to learn about how you can fix an air compressor tank check valve. There are two ways to fix the problems caused by a check valve.

Cleaning the Check Valve

Sometimes, all that a faulty check valve requires is a little cleaning to properly function again. If you find your check valve has problems, you can simply clean the check valve. There might be dust or grimes attached inside the valve that makes the valve to malfunction.

You can use water or clothes to clean the inside of the valve. If you find the disc is dusty or the seat of the valve has dust on it, you should also clean them properly. After cleaning, repeat the test I have given above and you will know if you can use the check valve again or not.

Replacing the Check Valve

If you see that any part of the check valve is broken, then it is time for you to replace the check valve. You can also repair the check valve by replacing the broken part.

For example, if you have a broken disc, you can replace the disc. But this will not work for a long time. In this case, it is always better to replace the check valve.

FAQ

What is a check valve?

In a piping system where air flows through the pipe, a bulb is used to stop the back-flow of the air. This is called the check valve. Check valves are also called non-return valves or NRVs.

The valve gets opened when air is flowing with a pressure level, but the valve closes if there is a reverse flow. A certain pressure level is required to open the valve in one direction only. If air flows below that pressure level the valve won’t open.

How does a check valve work?

To open or close, a check valve relies on the flow line of air. There is an internal disk in a check valve. It opens and allows the air to pass only forward. When the airflow rate or speed decreases the disk starts to close. And when the flow is reversed the disk closes completely.

Other parts of a check valve include the body, cover and the seat. These are the main parts but there may be other parts like hinge pin, spring, disc arm, etc. The seat of the check valve is responsible for the internal sealing. Metal sealed surfaces of the seat can leak but elastomer sealed surfaces are tight.

Does an air compressor need a check valve?

The main purpose of check valve in an air compressor is to stop air to flow back in when it is flown out through one way. As you have seen, the check valve allows only one-directional flow, so air compressor requires this to maintain the airflow in one direction.

By keeping the flow in one direction, check valves keep an amount of pressure on certain parts of the compressor. Other parts are also kept from pressure by the same principle. To, maintain this one-directional flow and pressure to certain parts, air an air compressor needs a check valve.

Is a non-return valve the same as a check valve?

A check valve and a non-return have the same purpose and they are quite similar. A check is often referred to as a non-return valve as well. There is only a slight difference between the two.

That is, a non-return valve does not need any specific criteria to be fulfilled. For example, the allowable pressure level of a non-return valve can be of any number. It doesn’t matter. But for a check valve this criteria matter. So, you can say a check valve is a non-return valve with specific criteria.

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 pressure level of the flow by allowing a certain amount of pressure of air to pass through it.

Why check valve is required at pump discharge?

At pump discharge, a certain level of pressure is needed in order to do a specific task. For example, say you need a 120 psi pressure to come out of the pump for nailing a pin on the wall. If you don’t get enough pressure then you can’t do the job. However, a check valve ensures you get this pressure.

It does that by blocking the air to go in the reverse direction. As the air flows only in the exhaust direction for the check valve, it helps to maintain that pressure level. This is why the check valve is required in pump direction.

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

A gate valve is more like an on-off switch for a piping system. When a gate valve opens air flows through the pipe. It can flow in both the direction. On the other hand, a check valve only allows the air to flow in one direction. This is the main difference between the check valve and gate valve.

Do check valves fail?

Check valves can fail from time to time. The failing occurs due to a faulty check valve. It can also occur if the check valve is really old and hasn’t been replaced yet. However, this guide on air compressor troubleshooting: check valve has already given the solution if the check valve fails.

5 thoughts on “Air Compressor Check Valve Troubleshooting: How to Identify, Test and Fix”

  1. Hi good time i have 1 atlas screw compressor When i turn off the compressor the oil in the tank returns and the oil spills out.

  2. About a week ago, I was talking to my brother, and he mentioned that his air compressor for his hobby garage shop was acting up. Now, apparently, it isn’t working at all. Thank you for informing me that a check valve prevents the flow of air backwards and can get dirt in it that prevents operation. I have no idea what could be wrong with it, but it sounds like he should get it looked at. Maybe there are services that could repair it.

  3. My air compressor is leaking at the check valve after filling up ,how do I know its not the valve itself but a bad pressure switch the diaphragm inside the pressure switch is gone bad?

  4. My compressor is leaking around the check valve when the tank fills up and shuts off ,how do I know it’s not the valve itself or the pressure switch is bad tank is full pump cut out pressure air leaking around the valve?

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