How to Configure Single Action Cylinder

We are using this single action cylinder (https://www.mcmaster.com/6498K273/) and this solenoid (CKD Single Solenoid Valve with Fixed Wires - AndyMark, Inc). We wanted to know if:

  1. is it legal to only have one tube from the solenoid go to the cylinder; the other fitting on the solenoid being replaced with an M5 bolt as a way to prevent flow when the solenoid switches states; the other fitting on the cylinder being left open to have the spring side fill with air.

  2. is there anything that we can purchase to prevent debris from getting into that open side of the cylinder we left, such as a fitting that is just a mesh, that is FRC legal.

The idea is to only use air for one actuation, as the other is done with the spring, to conserve air.

You could attach a 90 degree fitting, and have it point downward, to keep debris from falling into it. You don’t need a filter.

As long as the pressure all gets released when you open the manual pressure release, you should pass inspection, as far as I know. We’ve done this in the past.

A M5 bolt is functionally equivalent to a pipe plug. I don’t see an issue with it. You will want to use a seal ring or gasket under the bolt head so it doesn’t leak. Straight thread fittings, unlike tapered pipe threads, don’t seal on the threads

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A single action spring return cylinder only has one port.

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This picture on the McMaster-Carr website may be causing the confusion. It shows what looks like an extend port on the right end, but I agree that port shouldn’t be there. The callout “1/8 NPT Port” has an arrow pointing only to the correct (retract) port.
https://www.mcmaster.com/6498K273/

This may be against the rules because technically a bolt doesn’t have a manufacturer pressure rating per R802

I could be mistaken on this though.

A threaded plug is probably a better solution in general though.

Something like this?

which is essentially a bolt

A bolt probably won’t seal properly. You can put the regular push fitting on it, insert a tube and then kink it with a zip-tie.

If I was to do this, I would teach the team to call it be its proper name. “M5 pipe plug”. Any inspector with enough pneumatic experience to know the difference would not care. The factor of safety on this for a 60 psi system is so high it is not worth the trouble to calculate. (Been there done that). You will fail at the aluminum valve body threads just like any other fitting. But you correct a FRC rules lawyer would probably agree with you. The other option is to use and actual M5 plug like this.

My god. Forbes has faster google fingers than I do. :slight_smile:

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I am 100% arguing on a technicality in the rules. I prefer inspections go really smoothly, so I always do my best to eliminate anything questionable, especially for $1.20.

I can’t find a pressure rating on that one either, but maybe it exist. A bolt, or that would 100% work, but could violate the rules, and be noticed by a thorough inspector.

One of these would work: https://www.mcmaster.com/4948N12/ There are probably lots of solutions that would work that have a documented pressure rating. This one is also super low profile, which would be nice.

You need some sort of seal ring or gasket. My favorite is copper washers. You probably have least 3 of them on your car. A quick mental count on my motorcycle is over 8.

Oh, I totally see where you’re coming from.

Another way to legally plug the fitting on a solenoid valve that uses metric fittings, is to use a piece of tubing, connected to a T fitting, and the other two sides of the T fitting are connected to each other with a single piece of tubing.

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If you -actually- seal that port you will get some funky behavior as the cavity pressure cycles and it leaks over time!!!

What you really want is a muffler if you just wantnto keep out crud. McMaster has four in M5 size. Here’s a cheap one.
Air Mufflers, Nylon Plastic Fitting, M5 Male Thread

https://www.mcmaster.com/8457T66