Leakage - Small Compressors

[Randy Heinemann]

Is it common for small compressors to leak a tiny bit of air when just sitting unused over a period of a few hours?

I just bought a new coiled hose for my 2-gallon compressor which I use for my nail gun and pinner. I connected the hose with a quick connect fitting, ran it till it reached a tank pressure of 120 psi, then let it sit with no tool attached. The tank pressure was down between 15 and 20 psi when I checked after about 2 hours. Since I had to reinstall the hose on the connectors when I got it, I'm just wondering if I should just return the hose.

Is the amount of leakage I had normal for a small compressor? Granted it's a small amount but . . . normal? Since I don't run it unless I have a tool connected and am using it, I really never noticed any leakage.

[Greg Quenneville]

First get a spray bottle with some soapy water and check for connector leaks. You may have to redo every threaded connection with teflon tape or thread sealer

[Richard Coers]

It's nearly impossible to not get leaks with air under pressure. Did you buy high end hose and quick disconnects? I've never found a Harbor Freight quick disconnect that didn't leak. I've always had a ball valve mounted to the tank of my 80 gallon compressor and unplug portable ones. I don't want compressor cycling in the middle of the night and never want it running all night long if a hose blows.

[Bill Dufour]

Almost all cheap check valves leak.
Bill D

[Lee Schierer]

Oil less compressors are notorious for leaking back through the reed valves.

[Cameron Wood]

I have four portable compressors. Only one holds pressure so that it doesn't cycle periodically- ironically, it's the oil-less one.

[Tom M King]

I have five compressors (edited to add: not including the 12v ones in vehicles). Only one doesn't leak down, and it's the little California Air with a cheap hose on it with no quick disconnects other than the end of the 15' hose that stays on it. As long as they don't make noise, I don't chase small leaks.

[Randy Heinemann]

I decided to reinstall my old hose and duplicate the test; namely install the old hose on the compressor, fill the compressor to its auto shut off point, and let it sit with no tool attached for over 2 hours. No leaks. The pressure was identical to when it was filled. I am returning the hose.

I appreciate the comments. The hose was not Harbor Freight nor were the quick-connects. They are JACO, a local company from whom I've bought other air connections and gauges; all high quality and all work well. This was a new product and I had always wanted to replace the hose I had with a little better, more flexible hose, but I guess I'll just keep the old hose since it doesn't leak.

[Curt Harms]

I usually had the factory drain valves leak once I drained the tank. I did the street ell - 12" nipple - ball valve mod on the drain, that fixed that leak. I have my compressor sitting under a bench. The outlet is at the rear of the tank and I didn't want to pull the compressor out every time I wanted to use it so did a street ell in the pressure outlet as well then a length of pipe to the front to which another ball valve then the power/pressure switch is attached then a regulator and hose connection. It can sit for weeks and lose little if any air. I never had much luck with teflon tape and compressed air but pipe dope does the trick.

[Randy Heinemann]

Other than temperature changes, which cause decreases or increases in air pressure or leaving a compressor with a full tank for days, I've never had a compressor which leaked noticeable over a couple of hours. The company which made the hose, JACO, is replacing the hose even though I've already returned it for a refund; so the hose will be free in the end. I'm curious whether I have the same experience with the replacment directly from the company (not Amazon). If so, I'm not out an money, just time involved in the whole purchase, installation, and return process.

[Jim Becker]

The little red Husky compressor I have for super portability will hold air for months without leaking...the 20 gallon Mc-whatever I recently bought from HFT to eventually be the "garage" compressor when the shop moves to the new building also seems to hold air extremely well straight from the factory. Note that both had the quick connects already installed when I bought them; the Husky many years ago and the HFT unit last week. (The latter actually has an easy to use, easy to access ball valve for draining from the factory, too)

[Dave Sweeney]

I have two compressors, a pancake and a 30 gal. I have taken apart and redone the piping joints I don't know how many times and they both would not hold pressure for any length of time. I decided that the issue was with teflon tape, it just doesn't work that well with air pressure. I once again took all the joints apart and removed all the teflon tape and redid them using Tru-Blue Thread Sealant, https://www.menards.com/main/plumbing/plumbing-installation-repair/pipe-sealants-caulk-putty/rectorseal-reg-tru-blu-pipe-thread-sealant-1-75-oz/31782/p-1465526813469-c-8531.htm?tid=256103585882348442&ipos=14 . It's been over a year since I redid those compressors and neither one has lost any air in that time. Other thread sealants may work but I'm sold on the Tru-Blue.

[Michael Schuch]

Every air leak I have had in any compressor has always been due to cheap (and sometimes not so cheap) air fittings, mainly quick connects.

[Bill Dufour]

QUICK And easy test throw the hose end with quick connect into a bucket of water with. a drop of soap mixed in. Come back in ten minutes and look for bubbles.
Bonus the hose is now clean.
Even HF quick connectors can be rebuilt if you can find the right size O-rings.
Bill D

[Bill Dufour]

Many air and garden hose connectors are poorly designed. the hex portion is to narrow and a normal wrench will jam before the connection tight. I have to use a service wrench for many of these. A garden hose should not need a wrench of any kind to be made leakproof.
I guess Chinese fingers are less then half as thick as mine.
Bill D

[Derek Meyer]

I have a small California Air Tools compressor that I once left under pressure for weeks and it did not leak in the slightest. This was with a 25' air hose and Senco 18 gauge nailer attached.

[roger wiegand]

My cheapo 60 gal compressor that is hard piped to about 5 locations in the shop cycles once every day or two if not used. Over a month, when we travel, I usually shut it off and it bleeds down to 15-20 pounds pressure. I haven't yet been motivated to track down the leaks. I keep waiting for it to die so I can upgrade to something that will better handle air sanders and sprayers, but it seems at this point that it might outlive me.

[Jim Becker]

Roger, my 60 gallon behaves similarly. When I relocate it to the new shop building, I'm going to take off the quick connect and reinstall it using sealant rather than just teflon tape that's been there for, oh, a couple decades almost. Hopefully, that will reduce or eliminate any slow leak-down, other than what occurs with the auto-drain system. (it's been without that for a bit as the old one died, but I have a new one to install when I move it to the new building)