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Time Duration of fuel tank pressure test?

Daniel S.

Well Known Member
Hey all-
I'm finally pressure testing my tanks... I'm using a digital Manometerand can measure down to the 1000th of a PSI. I'm testing at 0.996 PSI at the moment. I was going to leave it go in record mode / temp record mode over night. What do you guys think is a reasonable test duration time?

Thanks,
D
 
Daniel, no offense, but how will you know if it passes or fails? I've got a feeling temperature changes alone will cause pressure changes, not to mention changes in barometric pressure, especially when you're measuring changes at that detail.

I test for leaks all the time at work on piping systems, and the best results are obtained using a spray bottle of soapy water. Plus you get the benefit of actually seeing where the leak is occurring. I'm at the same stage as you and that's what I plan to do in a day or two. I'd sure like to know your results, though, and above all I hope you have NO LEAKS! ;)
 
Is sprayed it down methodically with slimey leak detection fluid and came up null. Pressure dropped from 1 psi to .992 and due to the temp of the fluid. Brought it inside to a stable 73 degrees and its sitting at a constant 1.209 psi. I'm figuring if there is an average of <= 2% over night. At 73 degrees, I'm good to go. I figure its better than the balloon test or water manometer. As long as it doesn't drop below the min, it should be fine , right?
 
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I used the water level manometer method and left it set up for three days. It fluctuated up and down with the temperature changes but after 3 days, I was satisfied there were no leaks.
 
Glad to see you obtained the electronic manometer. I kept the tanks in my conditioned shop overnight. If you get up the next morning and the pressure has changed very little you can bet there are no leaks. No soap bubbles needed although I did use them. Experiment with it and you can see how accurate that is vs a balloon. Loosen a fitting slightly and retighten and listen to how little volume escapes to change the reading.

I use a micron gage to check for refrigeration leaks. The gage reads the last inch of mercury while pulling a vacuum, which is approx 25,400 microns. If my system stays at 500 microns or less I am good.
 
my recent experience

I just did this and wrote up my experience on a recent post. At nearly one psi, if you have even a small leak you will see loss of pressure virtually immediately (At least I did in my water manometer at 1 psi). I located the leak by immersing my tank in my hot tub at home. Located in a corner, where three sides converge, it would have been hard to get a film of soapy water over that area.
I did an overnight leak test with a balloon as well, after I repaired the leak. Inflating a balloon takes just over one psi, but an inflated balloon only needs about one half psi to remain inflated, so I agree with using a manometer or sensitive gauge
 
Results at 10 hours

Thanks for the input guys!!!! Okay, after looking at my picture log, I had mis-quoted some pressures.

While cool after get doused with leak detection fluid, at the beginning of the test, my pressure was reading 0.994 PSI.

After I stabilized the tank in the house at 74 degrees , It was sitting at 1.026 PSI at on hour in.

After reprograming all the thermostats in the house to 73 degees (I hate those programmable thermostats, BTW!!! they have a mind of their own). At 2.5 hours in, the tank pressure was stable at 1.016 PSI. I went to bed at this point.

This morning, I ran down stairs like a kid on christmas morning to find the tank pressure at a perfect 1.010 PSI with a temperature of 72 degrees... I could touch the tank with my warm hand and the pressure would go up to 1.017 PSI... This was at 10 hours. With a total max varience of 0.032 PSI over 10 hours and a solid average of 1.012 PSI over 10 hours, I'd have to say this tank is a wrap!!! :D

Thoughts?
 
Yep, sounds like a leak free tank to me. The smallest leak would show immediately on a digital scale. My fuel cap required a little tweaking. It was barely detectable with soap bubbles but the manometer was slowly counting down. If the tank holds over a lunch break I would call it good.

Chuck
 
FYI -- in the balloon test, the balloon is simply a pressure relief valve to insure that you don't rupture the tank when you pressurize it . The actual leak check part is the soapy water. In no way is the the balloon a substitute for a manomenter even if by chance there's some kind of coorelation in the results.
 
I think we're done on this one, My Wife called me with updates. Here are the final results... I'll have my wife leave it going till I get home but I have absolutely no concerns with this tank. Only time will tell now.

Right tank Pressure test

PSI Time (hh/MM) Temp
0.994 0:01 69
1.014 0:15 73
1.015 0:16 73
1.026 1:30 74
1.016 2:20 74
1.015 2:30 74
1.010 9:22 73
1.007 12:22 73
1.014 15.57 74
1.015 17:30 74
 
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