As I was reorganizing my air tool arsenal, a theoretical question popped in my mind I'd like to know the answer to. In designing air flow between an air compressor and a tool (such as a nailer or an impact wrench), when the tool is not taking air from the compressor, is there a mechanism to stop backflow of air from the tool back to the compressor? Are those mechanisms in the tool, the compressor, or both? Meaning, if the compressor suddenly emptied out, would air leave the tool to fill the compressor or is there a backflow stopper of some sort?

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    $\begingroup$ I'm not sure what the point of a backflow valve would be. The air in the tool doesn't pose any danger to the compressor or tank (as opposed to an oxy-fuel torch, in which backflow could be disastrous). Also, there's not enough air stored in the tool to make it worth salvaging pressure in the event that the tank depressurizes. Maybe in some industrial setting this would be a concern though. $\endgroup$
    – Carlton
    Nov 28, 2015 at 2:10

1 Answer 1


I doubt there is a backflow stopper, and I've never personally seen one on such a system. It doesn't make sense because:

  1. The tool isn't going to generate higher pressure than what the compressor is feeding it, so there is no danger from a little bit of air going back into the compressor tank.

  2. There is very little air stored in a tool, so basically nothing to block against. Any air in the tool is just a side affect of the tubing and the like having some volume. The volume of air in the tool is tiny compared to the compressor tank.

  3. Since there is no problem to solve, any cost spent on such a valve would only make the tool more expensive, larger, and heavier without any benefit.

Basically, putting a backflow prevention valve on tools would be silly.


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