HELP: Internal Solenoid Leaks Killed Us!

[Daniel_LaFleur]

Originally Posted by de_

We went from a major contender to losing the semi-finals for our alliance when our robot ran out of air due to increasing severe air leaks through-out the day this past weekend. We have one more chance next weekend but obviously our robot is in quarantine . We had already seriously tightened all brass fittings to the point soapy water did not find any leaks. We have yet to see any "push in" air hose fittings leak. We had tightened all the pilot valve screws and the manifold screws. Our best guess is we had joint seal leaks and or internal valve air leaks. But that was hard to confirm with soapy water as the valves were vertically mounted immediately above the spikes which could not get wet.

We had a number of people at the regional say that they had suffered from (more than one )"blown" solenoids (implying seals) and or leaking porous castings.

What is everyone elses experiences ? Since we are operating these values close to 1/2 their rated pressure and they are largely brand new and have only an hour of use (ie pressured), I am surprised we are in this position.

Anyone know how waterproof the pilot values are ? We would love to be able to dunk the complete solenoids for 10 seconds in a water tank under pressure with capped output tubes and tubes on the exhaust valve in a way that water can run up them but leaks from them would be obvious. That way all possible leaks will clearly be visible.

Anyone have any experience with the Festo valves ?

Our plan is to come in with tested spares, a standalone test compressor (with no reserve tanks: shows leaks much faster), replacement gasket kits.

Any other suggestions ?

There is another thread on leaks but for some reason its closed.

First off, as an engineer from Parker (Festos competitor) I can tell you that the Festo valves are far better than what the posts above will lead you to believe.

Most leaks with the Festo have to do with the quick compression fittings. Thise fittings require that the tube be cut square to the side of the tube and straight. If they are not then they will leak and they tend not to be easy to spot (for those that don't have a LOT of experiance with them). I would suggest popping each tube out of the valves compression fitting and recutting the tubes, making sure they are cut square to the side of the tubing, and then reinsert into the festo valve compression fitting.


Now on to how to test for internal leak of the Festo valve.

With the valve deenergized:
Apply pressure to the common (supply) port, seal off the Normally open port, and seal the normally open dump port with your thumb. If you can feel pressure building against your thumb then there is an internal leak against the normally open seat ... and the valve is bad.

With the valve energized:
Apply pressure to the common (supply) port, seal off the Normally closed port, and seal the normally closed dump port with your thumb. If you can feel pressure building against your thumb then there is an internal leak against the normally closed seat ... and the valve is bad.

If niether builds pressure then the valve is good.

One last thing, The Festo valves require 30 PSI to fire. If 30 PSI is not available on the supply port the spool within the valve will not move or worse, may move 1/2 way and cause a leak between the common and the dump ports. This could also be your issue if the pressure falls below 30 PSI during the valves operation.

Good luck.