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Every air compressor with a tank and unloader valve has a compressor tank check valve.
If you have had a chance to read the page on the air compressor unloader valve on this site, you will have already begun to understand why the compressor tank check valve is important to the unloader valve, and to the proper working of your air compressor.
Where is the compressor tank check valve?
Where is the compressor tank check valve on your air compressor? Typically it is located on the compressor tank where the line from the pump head reaches the tank.
In the photo above the tank check valve is seen within the red circle. The air line coming into the check valve from the left brings air from the pump to the compressor tank. The air line heading up and to the right is plumbed over to the compressor unloader valve.
Your tank check valve may not look exactly like the one in the photo, and, on many of the modern do it yourself type air compressors, the whole pump and control section may be entirely shrouded and you may not even be able to see where the air line from the pump head enters the tank. Still, that is where the compressor tank check valve is normally located, where the line from the pump reaches the tank.
What does the compressor tank check valve do?
Another name for a check valve is a one-way valve, and that’s what the tank check valve does.
I mentioned earlier that it works hand-in-hand with the unloader. The unloader valve periodically opens the line from the pump head to atmosphere for purposes of venting any air trapped over the piston.
If the tank check valve was not in this circuit, when the unloader valve opened, all the air from the compressor tank would bleed out the unloader valve to atmosphere too. The pressure in the tank would drop, the compressor would start, and then it would pump the tank up to the cut out pressure setting, the compressor would stop, the unloader valve would be opened by the pressure switch, and once again, all the air in the tank would bleed out.
The tank check valve prevents this endless cycle by keeping the air in the tank after the compressor pump has pumped it there, even when the unloader valve is open to atmosphere.
What does my compressor tank check valve look like?
Removed from the air compressor your compressor tank check valve could be similar in appearance to the one in the photo below.
In this typical tank check valve the small, bright male fitting on the left is where the line over to the unloader valve is connected. The part of this check valve above the red thread is inserted into the tank. The air line from the pump head would be connected to the female port not visible at the bottom of this one-way valve.
A non-functioning or poorly working compressor tank check valve is sometimes a problem for air compressor owners. See information on that under the fixing compressor problems tab.
Comments or questions about the air compressor tank check valve are welcome using the form below.