Tightening Pneumatic Fittings

I know you’re not supposed to tighten pneumatic fittings all the way but how do you know how much to do it? Does it change if you tape versus liquid sealant? Thanks!!

The sealant doesn’t really make much difference… Just tighten them until they’re tight. You should use moderate force on a wrench, and another wrench on the part you are tightening it into. If it leaks, it’s too loose. If you break stuff or strip off the hex, it’s too tight. You want it right in between the extremes.

A good way to test for leaks in your pneumatics system is using soapy water.

Get some loctite 545, spin the fittings till they’re snug, never worry about leaks again.

Tighten until you hear a pop, then back off 1/4 a turn. :grin: /s

Here’s a good quick reference.

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I never do pneumatics, but why are you not supposed to tighten all the way? Cause I think I did this like a day ago and I don’t wanna break anything.

The threads on most of the fittings are tapered pipe threads. You can keep tightening them until something breaks…they will keep turning, there is no “stop”.

^^ What @MrForbes said, but I’d recommend stopping BEFORE breaking anything.

However, if you are using non-tapered threads, these are usually sealed with an o-ring or similar gasket. Over compressing the gasket can cause it to move out of position to seal the joint.

1.) Right or wrong, our students learn to tighten fittings by the ‘feel’ of tightness that it takes to prevent/stop an air leak… learning by testing and re-working fittings is a great teacher.
2.) We only use Teflon tape.
3.) If I would see a student turn a fitting backward (eg. to adjust alignment) I would remind them of the risk of leak, and would highly suggest they take the time to remove the fitting entirely, remove and re-apply Teflon tape, and re-install to the desired orientation.

(Our 2018 robot was pressurized recently to 120psi and we forgot to release the pressure at the end of the night. Two days later it still had more than 100psi.)