Leaky Valves

[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?

[billbo911]

Without seeing how you assembled them after you replaced the 24vdc solenoid with the 12vdc solenoid (You did replace the 24vdc solenoid with the 12vdc solenoid as instructed didn't you?), I can only guess that the gaskets were not replaced properly. Dis assemble them and verify the correct positioning of the gasket(s).

[Nate Laverdure]

Soapy water is great for solving this problem!

Get a cup of water, mix in a little liquid soap, and drip it over all of your pneumatic connections with your fingers. Don't use too much-- you only need a little. Turn on the air, and watch as all of the leaky connections blow lots of soap bubbles!

We got our system from 40psi to 120 using this method.

[Kevin Sevcik]

Other possible problems are that you didn't wrap your fitting with teflon tape. And I think the solenoids leak if you hook them up the wrong way around. But I might just be lumping them in with the regulators on that one.

[chris31]

Originally Posted by Kevin Sevcik

Other possible problems are that you didn't wrap your fitting with teflon tape. And I think the solenoids leak if you hook them up the wrong way around. But I might just be lumping them in with the regulators on that one.

To echo what Kevin says. The Teflon tape, when used correctly, works wonders.

[sanddrag]

there are two really tiny phillips head screws on top of it. Try tightening those. If you ask me, it is a poor design, and there should be 4 screws. But, they will hold pressure with the gaskets installed correctly and those 2 screws tight.

[Tim Delles]

With pnuematics there is a "just right" spot. It can't be to tight and it can't be to loose (this goes for both fittings and solenoids).

[DonRotolo]

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?

The valves are air-operated pilot valves. Unless there is a certain pressure in the system, your valves cannot switch to one position or the other, and someone must have turned the little 'knob' to move the valve before there was pressure.

To reset the valve, you need to build up pressure. Simply place a finger over the valve vent (the one with nothing connected and a lot of air escaping), you can easily hold in the pressure, and the valve will self-reset at about 30 PSI.

Write back if that's not it.

Don

[Chris Fultz]

some things to check, in a slow, methodical order.

1. be sure your regulators are not set to limit the system to a lower pressure.

2. take the valve bodies off of the base units. be sure the thicker gasket was used. it will have two holes in i for the screws. (it you do not have a set of miniature screwdrivers, buy a set just for the pneumatics).

3. Remove the fittings and carefully clean the teflon tape off of them. clean out the threads as well, but be very careful.

4. Wrap the fittings with one wrap of tape and then install them. Finger tighten and then use wrenches and carefully tighten.

One key is to take your time. Find a table and sit down and relax. If you rush, you will be doing it all again.....

[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"