Leaky Valves

[kmcclary]

Originally Posted by Mark Deutsch

We're trying to assemble our pneumatics system, but we're only able to get pressures up to 20 psi. We can hear and feel air escaping from the double solenoid valve, but we're not sure how to stop it. Any suggestions?

Suggestions:

1) If it is leaking between the valve body and the manifold, make sure you are using the right gasket!

There are two gaskets in the assembly kit, as this is a generic gasket set that covers many different manifold/valve combinations. If you use the wrong one, it'll leak.

2) If it is leaking somewhere around the fittings, the most likely causes are:

a) improper fitting tightening
b) improper Teflon Tape technique (winding in wrong direction, too little, too MUCH, or improper placement - it should start one thread back from the end, wrap clockwise [when looking at the end of the fitting], and I get best results with about 1.5-2 full wraps.
c) bad threads on the fitting and/or the manifold - can be caused by cross threading, overtightening, etc.
d) improper trimming of the tubing before insertion into one-touch push fittings - the end must be clean, cut at 90 degrees (no "Julianne" chef cuts!), and have no nicks or burrs.
e) improper seating of the tubing in the push fitting. When pushing in, it should first resist, then seat with a slight "snap in" feeling.
f) Damaged retainer in the push fitting - often cause by someone improperly removing the tubing previously (pulling the tubing out without pushing in the ring). Replace the connector.

You can easily diagonse leaks by spraying all connection seams lightly (while they're under pressure of course!) with either Windex, or water with a bit of detergent in it, placed in a pump sprayer. Leaks will bubble. (You can get commercial "leak detection fluid" at any hardware store, but this is cheaper, and faster.)

I hope this helps!

- Keith McClary
Chief Engineer, Team 1502 "Technical Difficulties"