Pressure tubes disconnecting

[Mark McLeod]

Straight cuts on the tube ends?

It sounds just like they might not be pushed in all the way.
Try pushing them in, then going back and pushing harder.
You should be able to feel if they slide in a tiny bit more.

I've never had a problem with them popping out of the FIRST Choice push-to-connect fittings or the older KOP push-to-connect fittings.

[Mr. Lim]

Originally Posted by Mark McLeod

Straight cuts on the tube ends?

It sounds just like they might not be pushed in all the way.
Try pushing them in, then going back and pushing harder.
You should be able to feel if they slide in a tiny bit more.

I've never had a problem with them popping out of the FIRST Choice push-to-connect fittings or the older KOP push-to-connect fittings.

^This

I've had problems in the past if tubing is not cut square and clean at the end. An angled cut, or jagged edges will cause issues.

The more common problem I've seen is that tubes are just not pushed in completely.

Push the tube into the fitting as far as you can.

Then pull on the tube firmly, but not too hard. The tube should not come out of the fitting, but the plastic release ring should slide out a bit.

Push the tube in again, and pull firmly again. The tube should go in a bit further when you push, and when you pull, the release ring should slide out even more.

Repeat until the tube is in as far as it will go, and the release ring is as far out as it will go. In fact, the release ring should feel "loose," like it will rattle around a bit. It should reach the same position as if there was no tube installed at all.

If the release ring is still pressed in after installing the tube, and feels "tight," you need to push and pull the tube in farther.

[MrBasse]

I can't say for sure about other brands, don't know why they would be any different, but with the Parker fittings it was reccomended while I worked there to insert the tubing fully and then pull the tubing with some force to seat the barbs in the collet. The way the push to connects works is by making use of the pressure in the line to clamp tighter and tighter holding the tube against an o-ring. You should be able to run these fittings almos to the burst rating before the tubing will let go.

Do as others have suggested, cut your tubing straight and insert it as far as you can. ThEn pull on he tubing gEntly to seat the barbs into the tubing. You really shouldn't push in and repeat over and over again as the barbs will damage the tubing slightly, weakening their overall grip. One solid push and then a gentle pull on the tubing should suffice.

[JCharlton]

All of the above suggestions are good, to repeat:

• Cut the ends straight and clean

• Insert it all the way

• Give it a tug to seat it well

• Don't have tension on the tubes, keep them loose

• If the tube has been inserted a few times, replace it

And I'll add one that I found in our kit of bits

• DON'T BE MIXING METRIC AND IMPERIAL!

[Camren]

Our team is always solely pneumatics based. Here are the things I learned about the tubing and connections.

- The tubing will take a load of at least 100 working pressure. (Tested)
- Insert firmly with the push in piece kept outward allowing the teeth to grab better.
- Do a pull test.
- Leave slack.
- Cut the tubing straight or else the teeth wont grab right.
- Don't use push in fittings unless its at a spot of high maintenance.

One other thing:
Has anyone found that some of the tubing from FIRST and AndyMark are kind of small for the connections. We kept having problems with the clear blue tubing that was bonded together in a group of 4 or 5?

[tsaksa]

[quote=JCharlton;1189412]All of the above suggestions are good, to repeat:

• If the tube has been inserted a few times, replace it

This is a training opportunity. I find that students will usually assume that anything that plugs and unplugs has an almost unlimited insertion life. They will plug and unplug these connectors many times during debug or while assembling other things near the connector. They will not think twice about it, or tell anyone they did it. They just do not think it matters, but it does. Make sure all students working on the robot understand the importance of maintaining the integrity of these connections.

[Camren]

[quote=tsaksa;1189562]

Originally Posted by JCharlton

All of the above suggestions are good, to repeat:

• If the tube has been inserted a few times, replace it

This is a training opportunity. I find that students will usually assume that anything that plugs and unplugs has an almost unlimited insertion life. They will plug and unplug these connectors many times during debug or while assembling other things near the connector. They will not think twice about it, or tell anyone they did it. They just do not think it matters, but it does. Make sure all students working on the robot understand the importance of maintaining the integrity of these connections.

Easy way to avoid this is cut an inch off if you have enough slack and then insert. Also along with this the teeth that hold the tube get dull as well so replace fittings every year for the best hold.

[roystur44]

Check to make sure the diameter of the tubing is consistence. Check with veneers or a micrometer. Replace a failing connector with another and observe.

Check the final pressure of the tube. Could be your overpressure sensor does not turn off correctly resulting in over pressuring your system.

Important to have a procedure for leak testing your pneumatics.