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Tank air pressure

Ottoman

Member
How much air pressure should I use when testing my tanks for leaks? If I use the balloon method, should I pump it up until the balloon is firm?

Thanks,

John
 
Manometer

How much air pressure should I use when testing my tanks for leaks? If I use the balloon method, should I pump it up until the balloon is firm?

Thanks,

John

I used a Manometer. 27" total. 1 psi.
Sounds like nothing but she groaned a little. Don't go more than that.
 
Somewhere I found a pressure gauge that read to 5 psi. Cobbled up some fittings and a valve and pressurized the tank(s) to a hair past 1 psi (so I could see the "1" mark). 1 tank held for 2 days, one leaked immediately. Fortunately the leak was in the BNC fitting for the capacatance fuel quantity and easily fixed.
 
Somewhere I found a pressure gauge that read to 5 psi. Cobbled up some fittings and a valve and pressurized the tank(s) to a hair past 1 psi (so I could see the "1" mark). 1 tank held for 2 days, one leaked immediately. Fortunately the leak was in the BNC fitting for the capacatance fuel quantity and easily fixed.

After messing around with water, plastic hoses and fluctuating temperatures in the garage , I broke down and got one of these: https://www.amazon.com/gp/product/B00N3PPZZY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Apparently I can also check the static system for leaks later when I get to that stage.
 
Balloon

A balloon inflated to its proper size is really all you need.
When inflating your tank, reduce your pressure setting on your
hose to a bare minimum so you don't accidentally over inflate.
You can spend 50 bucks for fancy equipment or 2 cents for a balloon, they both
do the same job.
4 tanks and no leaks for me using the balloon method;)
 
A balloon inflated to its proper size is really all you need.
When inflating your tank, reduce your pressure setting on your
hose to a bare minimum so you don't accidentally over inflate.
You can spend 50 bucks for fancy equipment or 2 cents for a balloon, they both
do the same job.
4 tanks and no leaks for me using the balloon method;)

+1 on this...and dont forget to use a soapy solution (i used kid bubbles) to check for the leaks.
 
tanks

Thanks to everyone for the quick replies, I have to scrounge up a couple fittings, then test on Monday.

John
 
I'm doing this today with the tanks on the -10 project. The original builder seemed to have done a conscientious job with the tanks, but there was a leak along the outboard bottom aft baffle anyway. The leak occurred in a little raised area of proseal that had a tiny little void in the center. Kind of like a 1/1000000 scale volcano.

Looking through the fuel filler hole, plenty of proseal squeezed out of the baffle/skin joint, but there are 3 places where there are small pinholes in the proseal.

Skygeek has the flowable (A) proseal pint on sale for $25, so I've got some of that on order. I figure I'll apply it inside the leaky tank with a syringe and flex tube, and will brush it on the outside of the seam. While I have the brush in hand, I'll probably brush the outside seams of all 4 tanks, on the 1% chance that it might prevent another leak.

To pressure test, I taped over the fuel cap with packing tape, capped the fuel line, placed a balloon over the fuel vent, and pressurized the tanks through Schrader valves threaded into the fuel drains. I only applied enough pressure to make the balloons taught - not expand them.
 
I did both simultaneously at first. The balloon burst at .5 psi. A Balloon is simply not a reliable measurement device. Van's indicates that 1psi should be your target test value. Just don't over pressure it, so cut the hose off or bend it over at this point so you can't. I then just used the manometer and took it to 27in of head. I used some clear plastic 3/8" hose I bought at the hardware store, flared the end and used an 818 nut and 819 sleeve to attach it to the tank. You should have plenty of these in your bag of fuel fittings. It really isn't that complicated, but it is accurate.
Tom.
 
I did both simultaneously at first. The balloon burst at .5 psi. A Balloon is simply not a reliable measurement device. Van's indicates that 1psi should be your target test value. Just don't over pressure it, so cut the hose off or bend it over at this point so you can't. I then just used the manometer and took it to 27in of head. I used some clear plastic 3/8" hose I bought at the hardware store, flared the end and used an 818 nut and 819 sleeve to attach it to the tank. You should have plenty of these in your bag of fuel fittings. It really isn't that complicated, but it is accurate.
Tom.

Soap bubbles are your leak indicator, not so much the pressure the tank holds.
 
Interesting. I ran my test for a day and tracked the atmospheric temperatures and pressures to account for any differentials in the manometer height. There was no change in my manometer level once these factors were taken into account, thus I fail to understand how this is not an indicator of the presence (or lack thereof) of any leaks? I can understand using bubbles to pinpoint a leak once you have discovered that your tank does not hold pressure, but fail to see how this can provide benefit otherwise.
Tom.
 
Interesting. I ran my test for a day and tracked the atmospheric temperatures and pressures to account for any differentials in the manometer height. There was no change in my manometer level once these factors were taken into account, thus I fail to understand how this is not an indicator of the presence (or lack thereof) of any leaks? I can understand using bubbles to pinpoint a leak once you have discovered that your tank does not hold pressure, but fail to see how this can provide benefit otherwise.
Tom.
If you just go ahead and use the soap, you don't have to keep track of temperature and barometric pressure changes. No bubbles = no leaks. Simple as that.
 
I did both simultaneously at first. The balloon burst at .5 psi. A Balloon is simply not a reliable measurement device. Van's indicates that 1psi should be your target test value. Just don't over pressure it, so cut the hose off or bend it over at this point so you can't. I then just used the manometer and took it to 27in of head. I used some clear plastic 3/8" hose I bought at the hardware store, flared the end and used an 818 nut and 819 sleeve to attach it to the tank. You should have plenty of these in your bag of fuel fittings. It really isn't that complicated, but it is accurate.
Tom.

The instructions I have (came with the vans test kit) refer to the maximum pressure in the tank during operation being "very low, less than 1 PSI".

The manometer is then offered as an alternative to the balloon. "When the water level in the open end of the tube is 27" higher than the level in the end attached to the vent, you will have 1 psi in the tank". I do not read this as you MUST have 1psi, but rather that this is your limit. Again, the soapy water test is still specified as the method for detecting leaks.

IMO 1 PSI should be a LIMIT and not a TARGET, any positive pressure will show up leaks under the soapy water test, it doesn't need to be exact.
 
A note 1psi = 144 psf. I suspect 144 psf vacuum could result in a big problem while test pressure for leaks would be the upward limit unless you want to see if your riviting will hold up. Just a thought
 
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