Where is the Leak?

Have you tried soapy water in a squirt bottle to locate the leak?

Just spritz it on the suspected components and watch for bubbles.

Off topic?

My first job was working for a company that made gas fixtures and that was exactly how joints were tested. How silly.

It works perfectly and is used in many industries to catch leaks.

Maybe because the OP stated: "I've been making a regular mess with Snoop (soap bubbles). Snoop will not show the tiny leaks I need to stop." Which, by the content of your reply, you seem to have missed.

Good idea and I wouldn't call it off-topic.

Hey, we all have to start somewhere.

My first job was filling flux cups and wetting sponges on soldering stations in an electronics factory in 1966.

Can you charge it with Freon and use a Freon leak detector?

I don't think nitrogen detector will work, the air is full of nitrogen (at least 79% full). If it's too slow to blow bubbles, ultrasonic probably won't work either.

If you can pressurize with helium, you can use a mass spectrometer. If anything will leak, helium will. (I don't know the availability or cost of renting what you need).

This has some good information:

https://en.wikipedia.org/wiki/Tracer-gas_leak_testing_method

I was recently looking into leak testing fluid that could replace soap and water because it was causing rust issues. I came across this site that offers some fluids that detect some pretty low leaks and hopefully will help you out.

http://www.amgas.com/ltpage.htm

Propane for the pressure source, and a very, very, very long match!

Get out of my head.

This needs one vote for GA, one vote for "Are you nucking FUTS! This isn't a Three Stooges short, this is real life!"

So since I can't vote BOTH +1 and -1, I'll withhold my vote here.

Well, I tried to post a "devil" emoticon when I made that response, but the picture icon wasn't working.

But I did read back through his posts, to make sure I wasn't giving advice to an ID10T!

Well, anyone who would follow that advice is a candidate for a Darwin Award anyway.

We had the same type of issues with one of our dead-weight testers and finally after three days of troubleshooting, traced it down to the threads of the tubing fittings. Changed the bad tubing out and the problem went away.

Remove all your screw in fittings and reassemble with Loctite, if this does not fix it check all your "O" ring seals .

It is a process of elimination, Hopefully your pressure vessel has not developed any structural problems?

Todays troubleshooting involves Nitrogen/Hydrogen at 95% / 5% and a hydrogen detector. I'm also using a fan so I don't make national news.

I use a $40 gas leak detector when I'm working on LP or NG ranges. Why not use one of those and pressurize with Propane?

We have found that a leak that makes barely visible bubbles with nitrogen will make huge bubbles with helium. Also use a bubble agent made for the job. when dish washing detergent in water will hardly bubble, "leak detector" will make foam. -- JHF

Well the leaks were found with the hydrogen detector. It seems 3 years of vibration from the environmental chambers compressor and circulating fan caused 2 compression fittings to give up the good fight.

Thanks to all for input keeping me away from the types of sensors that would not have found the problem.