Troubleshooting Pneumatic Valve Leaks

Advice on valve maintenance and repair procedures. September 3, 2010

I have some air leaks coming from inside my housing box for the pneumatic valves. Before I go ripping things out I wanted to know if this kind of problem is common? If so, has anyone else had this problem before and how did they fix it?

Forum Responses
(CNC Forum)
From Brian Personett, forum technical advisor:
Not having any info, I would guess it could be a bad electrovalve. If so, it is pretty easy fix.

From contributor H:
Common problem? Yes. But moreover, I would say it's a constant problem. Once any of our machines are several years old we're constantly replacing worn air lines and valves, or at least disassembling valves to clean them. Valve problems are even worse during cold temperatures.

From contributor M:
I would suggest that you contact Rankin Industries (on-line ) for Univer and Pneumax valves. They are more economical than valves from the machine manufacturer, and most likely identical. Clean, dry, and moderately warm air helps a great deal.

From contributor B:
My air chiller recently failed and since I had a secondary filter style dryer at the CNC I thought I could take my time to find the right replacement. The secondary filter did a fair job of keeping moisture away from the CNC but all the other air cylinders on other systems around the shop were quickly giving me problems. So, in addition to checking for mechanical deterioration I'd suggest checking the moisture protection system at the same time.

From contributor I:
Are these single valves or a rack of valves stacked together? If it is a sindle valve, just replace the leaking valve. If it is a rack and is several years old then replace the whole rack/unit. As mentioned above they are all the same age so if one has failed the others may soon follow. The secret to long life pneumatics is clean and dry air!

From contributor K:
The number 1 cause of air leaking from control valves is a bad piston seal on the actuator that the valve controls. isolate the leaking valve, if the air is coming from the exhaust Manifold or "E" port on the valve most likely you have a bad actuator.

From the original questioner:
Thanks for all of the replies. The valves are the solenoid valves grouped in the box above the router. It seems like Iíll be replacing a couple or wait out the cold season since this is a new problem this winter.

From contributor L:
Contributor K is correct. Actuator seal is more than likely the cause.