I spent the weekend getting some pneumatics components together for a couple of small projects that has been back-burnered for a year. In the process, I was reminded of several things that bug me about working with compressed air piping and pneumatic components.
I’ve had frustrating time these past 2 days, so maybe this will come across as too grumpy. Overall, pneumatic fittings and systems are relatively easy to rig together. But when something goes wrong, such as a super-slow but persistent air leak (see #1), everything kind of ties together to bug the heck out of me.
I’ll probably shrug it off and live with the minute air leak for now, until it bugs me again (tomorrow?). But for now, every aspect of the compressed air system is getting on my nerves.
Some of this applies to air compressors from a tool context, some of it applies to air lines in an industrial and automation context. The couple of small projects I have in the works mainly involve the use of pneumatic actuators, and one involves a blower for a small CNC build. But some of these could be universal annoyances.
1. Air Leaks
20 hours into leak testing of my closed-loop system, and the air pressure is down from 60 PSI to around 40 PSI. There’s not a lot of volume in the system – the tank is only about 13.5 cubic inches, and then whatever’s in the air lines. But still, a leak is a leak.
I believe the leak has something to do with my air filter and regulator. But I removed the fittings, cleaned the threads, added new fittings, re-cut the air lines, and there’s no improvement.
The air filter and regulator connect together via a spacer device, but that seems to be a solid seal. If the leak is in the interface between filter and regulator, or in either component, there’s nothing I can do short of swapping parts back and forth to try to isolate the culprit.
I plan to do some quick leak detecting, but it’s not going to be easy.
2. Teflon Tape
I have some good teflon tape that I bought about a year ago with many of the parts for this project. Can’t find it anywhere. Am I the only one who always loses teflon tape? Good thing I have a cheap roll in my top toolbox drawer for times like this.
How many times to wrap a thread? 2 times? 3? Certainly not 1, and certainly not 5, at least for the 1/8 NPT fittings I’m using. Too little, and the tape won’t be effective. Too much, and it’ll bunch up. Use the right amount, and it might still bunch up.
I found myself in need of some 1/4″ teflon tape this weekend. They don’t sell it locally, and it costs maybe $2 online, plus $8 shipping. Eh, I can make do with cutting 1/2″ tape down the middle, as it’ll just peel apart with a starter cut, although this goes against my nature.
If I could use the kind of fittings that seal with a single rubber grommet or o-ring, I would, but they only make those for the smallest fitting sizes. There’s a new kind of “universal thread” fitting that has grommets across the line, but they cost a lot more and are tough to find in stock.
3. Push-to-Connect Fittings
Push-to-connect fittings are quick and easy to use. Except tube ends need to be perfectly straight. And once you remove a tube from a fitting, you have to cut the end before reseating it. If you don’t have perfect cuts, or reuse tubing, there’s a good chance of an air leak.
Do you know how hard it is to perfectly cut 5/32″ tubing, even with the right types of cutters?
Well, at least they’re not as much of a nuisance as barbed fittings.
4. Quick-Release Connectors
There are many different stands for quick release fittings, and I can never find the right one that I need.
I switched some stuff over to Legacy color-coded quick release fittings. I bought some at Amazon, and wish they were easier to find locally. Bad news is that the ones I bought (Type D) don’t work with more common standards, such as general purpose Type M.
For the recent small-tubing projects, I have a pair of inexpensive plastic-bodied disconnects ready to go.
5. How Tight is Tight Enough?
“Hand-tight and then a little more.” Sometimes a hand-tight fitting leaves too much thread sticking out, so I pull out a wrench. But then is it too tight? Teflon tape tends to slick things up, which is good and bad.
What bugs you about compressed air and pneumatic systems?