Did you use any 1/4 OD airline and push connect or compression fittings ? I've had issues with with them leaking if they are mounted in a certain way that pulls the airline out of alignment with the push connect fitting.

On my last truck my leak down was 160-120 over about 4 days. I never bothered tracking down the leak, but suspecting it was either the check valve in the compressor or one of the air solenoids.

 

You discovered what I discovered when putting in an air system. The thread sealant goop is more designed for a gas line which is not under the pressure an air line is. I ended up using the heavier yellow tape and it worked.

If you are still having a leak at this point sometimes your ears are what is needed. Listen very carefully to see what you can hear. This might be difficult if you can not get it in a garage for quiet.

You could also do the bubble test again on everything. Don't assume that it is just the fittings, I have had brand new copper tubing with pinhole leaks. Don't just use some household detergent though. Get a jar of Oatey Leak Detector. It is specifically designed for what are checking and will find even the tiniest of pinholes. I have never had the same success with dish soap or the like.

 

He's right, A/Ox4. If a compressed air tank explodes, it was not installed properly and/or with all parts, or it was a rare exception where the proper parts failed. Well, that's assuming that the tank itself wasn't already weakened and radically overpressurized. The point is that people who buy and install a new tank system should not have to be scared into thinking they're rolling around with a bomb underneath them just waiting to go off. Especially a little Viair tank and compressor.

And please link to that manual for the Ingersoll Rand compressor. I would be surprised if that weren't for a large capacity commercial shop air or paint shop compressor, where daily draining would be sensible, NOT an air system in a passenger pickup truck.

 

I have found that the hoses supplied with the compressors are generally not of the highest quality. We never use then when installing a unit. The cost of replacement quality hose is very inexpensive. Make sure you purchase the proper pressure line. Also, a compression fitting shouldn't leak if installed correctly. Make absolutely sure that yo are using S.A.E. fittings and not metric size line with the corresponding fittings. We discard the fittings supplied and use push and plug type in place of the compression ones.

 

I always thought the "drain daily" recommendation was referring to draining the condensate out of the tank, not the air. ????

 

It does. But there are only so many ways to get the water out of a pressurized vessel, so normally you have to let a good chunk of the air out of an average homeowner sized model to drain the water. The oil-less home owners models can build up a lot of water quickly compared to their storage volume, so it's common to completely drain them pretty regularly. On shop models you don't have to drain them all the way, and there are autodrains that do it for you, but those are more common on shop-sized or industrial models where the extra cycle time to refill is negligible to the overall duty cycle of the compressor.

Steel tank + water * time = rust. Eventually pinholes and air leaks. If you buy a used compressor for heavy or commercial use, get it hydrotested. Actual explosions seem pretty rare (all the ones I googled up were repairs where the welder tested the tanks with air ), but they can happen. If it's a cheap compressor and it's questionable, scrap it and get a new one.

 

The reason some manufacturers suggest (suggest, not require!) you to drain the tank after use is because the less air that is in there, the less water there can be. A tank with 100PSI in it has more water vapor suspended than a tank with 0PSI. As long as you drain the condensation on the bottom on a regular basis, this is not something you need to worry about, especially considering the small volume of a VAIR tank. They are designed knowing the tank will eventually rust.

It is most certainly not a fire safety issue. There are circumstances where air tanks blow up, it's rarely if ever caused by fire. If that was the case, you would find OSHA and other regulations relating to draining tanks, but you don't. Most commercial shops never ever drain the air from their tanks, they use automatic moisture drains. Most of the time a rusty tank gets over pressurized and then blows out a rust pin hole.

A real fireman would be concerned about the gas tank much more than the air tank...

 

Also, back to your leak: try isolating different parts of the system. Disconnect and cap off half of it, see if it still leaks.

 

SlowLearner : Yeah, I started with the 1/4" push connects and replaced everything with 3/8" line & compression fittings. After much tightening and re-tightening using Permatex thread sealant, I managed to get all the compression fittings to stop leaking (at least, I'm not getting bubbles in the soap water spray). However, there was a brass reducer fitting that came with the kit that would not stop leaking so, re-installed it using PTFE ("teflon") tape and that seems to have worked.

So now, I don't find any obvious leaks with the soapy water spray but, I'm still losing pressure slowly. 140 lbs down to 100 lbs in about 3-4 hours. I don't plan to have the system pressured up all the time but, I'd like to make sure I've got it tightened up as good as possible.

 

Pieces like this you might just want to replace. Could still be leaking. Have you checked your check valve? I'm not sure where it is on your setup, but it is very possible to have a small piece of something from manufacturing get stuck in the check valve and hold it open. It might be built into your compressor, you would have to take off the head.