Compressor tank check valves fail. Here are tips for buying a replacement compressor tank check valve when that becomes necessary.
Typically a compressor tank check valve failure occurs due to contamination building up inside the check valve, which prevents the flapper or sealing ball from closing tightly enough to prevent air back flowing through the valve.
Symptoms of a compressor tank check valve failure
The symptoms of a compressor tank check valve failure include air bleeding out the unloader valve all the time the air compressor is stopped.
If you are experiencing symptoms that suggest that the compressor tank check valve has failed, the first thing to do is to attempt to clean the check valve.
Cleaning the check valve involves first removing it from the compressor tank, disconnecting any air lines as that is accomplished.
Blowing air through the check valve in the opposite direction of normal flow, using some sort of solvent to clean out the inside of the check valve, and sometimes simply by flushing them with hot water can resolve the issue.
If those fail that means it’s time to buy a new one.
At this point we assume that you have the check valve removed from the compressor. If not, please do so and have a close look at it.
There are a couple of compressor tank check valves shown. Others may vary slightly from these, yet pretty much all will have the common elements as shown in the graphic.
Have a close look at it and determine where the line enters the check valve from the top of the compressor pump (marked 3), where the line goes if there is an air line from the compressor tank check valve over to the unloader valve (marked 2), and at the thread that threads into the compressor tank to determine its size (marked 1).
As long as the replacement tank check valve you acquire has these elements in common sizes with the old, the new tank check valve should work, regardless of the brand.
Not sure about fitting thread sizes? Visit the Sitemap page on this site, and scroll down to the NPT fittings and Metric fittings pages for information about figuring out the thread sizes on the compressor tank check valve.
It is not necessary to replace the compressor tank valve with one of the exact same make, a situation that may become necessary when smaller, lower cost, air compressors have a parts failure and parts for it are not available at all.
It is necessary to replace the tank check valve with one that has the same operation and fitting sizes, though bushings can be used if necessary to change the size of one or more of these threads to modify them to fit.
If you use your browser to search for “replacement compressor check valve”, you will find quite a selection.
Try to find one that looks similar to your existing valve. In particular, one that has a similar thread size, and similar connection ports for the lines from the pump head and the one that plumbs over to the unloader valve.
Once the compressed air gets into the air tank that is where it should stay until such time an air tool is connected to the discharge coupler on the compressor, and air flows down the air line to the air tool. Compressed air should never escape back up past the compressor tank check valve flapper to escape out the hose to and through the unloader valve.
If that is happening it’s time either to clean or to replace the valve, and if cleaning it doesn’t work, I hope this guide on how to buy a replacement compressor tank check valve helps.
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