Compressor not kicking off; calibration difficulties

The topmost one with the hole. The calibration instructions say to screw the cap, which is what I thought was the topmost part with the hole.

That’s the right one.

Next dumb question: Did you loosen the one right below that first?

Did you notice whether either of the others turned with it?

Yes, the locknut as the manual calls it.

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I knew what you were getting at, for what it’s worth. But I definitely appreciate any clarification where anyone sees fit.

They stayed put.

Correct. Bolts right in on the 1/8npt

If the relief valve is hissing it is leaking. It might be assembled improperly or misadjusted. It should be adjusted so it starts relieving at 125 psi. Depending on the dynamics of the system it might build pressure to 130 when properly adjusted. Once it relieves it might not reset until 115 or so. These are simple low spec valves. Cheap in less gracious terms.

The compressor and controls are working as they should. Fix your leaks and you will be fine.

SOLD. Just placed the order. Thanks for the tip!

Gotcha. s-neff pointed me to this https://www.mcmaster.com/9889k15-9889K624 and I just placed the order.

Here’s the regulator. The back outlet is plugged.

And that arrow is pointing toward the solenoid

Some other house keeping stuff. Tubing should be cut square. Automation Direct supplies a nifty tubing cutter in just about all of their pneumatic order. Paint all of the connections and fittings with leak detection compound. (see below) Once you are done you can use it to blow bubbles. Great squirrel activity.

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I have the neat little blue cutter thing from Automation direct and use it. I can’t imagine what squirrels will get out of it, but I’m gonna run to the store and get some bubbles later on!

So I disassembled the fittings that contain the pressure relief valve, scraped all the old tape off (there was no tape on the 1/4" to 1/8" adapter), retaped and then reassembled–but reassembled with a different pressure relief valve and used a table vise to steady the parts and tightened them all back down with wrenches. The Hulk could try and get these apart if he wants.

The hissing from the pressure relief valve stopped! The system holds stead-ish at 115 PSI, and kicks back on at 100 PSI unprovoked by actuation. So there’s still a leak, but at least the compressor leak is fixed!

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You can over tighten NPT fittings. The trick is to find just enough. Tape is also tricky too much is just as bad as not enough. Plastic into metal often doesn’t need tape. For metal on metal I generally prefer liquid pipe tread sealant. Loctite has provided an assortment of them in the KOP over the years. Many of the Loctite products are not intended for plastic though.

It is a bit finicky but you can get the system to hold pressure overnight. Less than an hour, I would put in the needs fixing category.

Powered off, it drops from 115 to 100 in 3 minutes 44 seconds. Which is, as you may know, less than an hour.

Off to find leaks.

Basically echoing what Frankj said:

Slow and steady and very very methodical wins the race with pneumatics. All metal to metal joints get 2 full wraps of teflon tape, or much better, liquid pipe fitting sealant. Metal to plastic should self seal. Metal to metal get snug plus 1/4 turn tightening, plastic to metal gets snug. Too much tape is likely worse than not enough (this is where the liquid really shines, since too much just creates a mess rather than stopping you from tightening it up properly)

Carefully inspect old fittings before reusing. Clean off all old teflon tape before apply new. Do not just pull the plastic pipe out of the plastic fittings, release them properly by pushing in the little ring. Ensure the plastic tubing is cut very square.

Some of the fittings that go in the solenoids are fussy. Some have tiny little rubber gaskets that are easy to crush or pinch creating slow leaks. These are also easy to over tighten and damage.

System should have no issues holding full pressure overnight, if it is stationary.

I’m nervous about using liquid sealant. Is it a permanent? Like if a fitting is connected to another fitting and later you find it’s incorrect is the whole thing hosed?

No, the opposite actually. It is easier to remove from a fitting you want to reuse than Teflon tape, as you can just wipe it off with a cloth. It is not a glue/epoxy/threadlocker sort of thing. It does not set. It is thin paste/thick liquid that you apply with a bristle brush. The stuff I use is made by Oatey (available is decent plumbing/hardware stores in North America) and is called “Great White Pipe Joint Compound with PTFE”. It stays flexible/non hardening for a really long time. Rated for gas connection up to 3000 PSI, and from -50 to 400 F.

It also is easier to apply than Teflon tape as you just “paint” it on the threads. Especially true for small fitting where you have to try to wrap tape neatly on a fitting that has less thread width than the tape is wide.

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Thanks! Any good tips on removing crusted and old thread tape?