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  #11  
Old 01-09-2014, 02:13 PM
Tony Spicer Tony Spicer is offline
 
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For photos of how to do it, have a look at the last 8 photos here. Should you want to see how to build Panther tanks, start at the beginning.

Tony
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  #12  
Old 01-09-2014, 03:00 PM
krw5927 krw5927 is offline
 
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Quote:
Originally Posted by BobTurner View Post
You need to use the local barometric pressure, not the altimeter setting. (close to sea level it won't make much difference)
The difference in two separate local altimeter settings at the same field is equal to the difference in local barometric pressure readings, when corrected to the same units of measurement.
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Last edited by krw5927 : 01-09-2014 at 03:03 PM.
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  #13  
Old 01-09-2014, 04:34 PM
Robert Anglin Robert Anglin is offline
 
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Location: houston, texas
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Default Party time.

I don't want to get into the barometric pressure end of this question.
We have had some of the balloons puff-up all the sudden on us. What we have found is put a little pressure in the tank, then take the balloon and stretch it with your hands. If it is ready it will blister for you. If not put a little more gas to it and stretch it again tell it does blister. Once it is going pump it up tell it is 3/4 full and start you test. If you go to the party supply store you can pick up some thin latex balloons. They are better at blistering on up with no prompting. Odds are you have not heart your seal, but test it and be sure. Hope this helps. Yours as always R.E.A. III #80888
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  #14  
Old 01-09-2014, 04:46 PM
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DRBuilder DRBuilder is offline
 
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Default Fuel Tank Pressure

I simply used a low pressure gauge. No questions here. I filled it with 1 psi and it held for days.


[IMG][/IMG]
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  #15  
Old 01-09-2014, 07:42 PM
BobTurner BobTurner is online now
 
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Quote:
Originally Posted by krw5927 View Post
The difference in two separate local altimeter settings at the same field is equal to the difference in local barometric pressure readings, when corrected to the same units of measurement.
1. Sorry, this is not correct. You only want the pressure, but altimeter settings include compensation for non standard temperature.
2. But what I really meant was that you need to use the actual barometric pressure, not corrected to sea level. That's what your manometer sees.
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  #16  
Old 01-09-2014, 08:52 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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You guys can use what ever procedure you want to measure pressure, and use what ever pressure reference you want, but the only way to truely check for a leak is to spray it down with soapy water.

The amount of expansion or contraction of the air that will occure with even small temp changes will make you think you have a leak when you don't or maybe fool you into thinking you don't when you really do. Baro. pressure is also a factor. What if your tank slowly leaks over a 24 hr period, but the baro also drops during the same time? Your leak indicator will say you have no leak... but you do.

The balloon (or manometer, or guage... what ever you use) is not meant to be an indicator of whether you have a leak or not. It is only to help prevent inexperienced airplane builders from destroying there fuel tanks.
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  #17  
Old 01-09-2014, 09:56 PM
krw5927 krw5927 is offline
 
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Quote:
Originally Posted by BobTurner View Post
1. Sorry, this is not correct. You only want the pressure, but altimeter settings include compensation for non standard temperature.
2. But what I really meant was that you need to use the actual barometric pressure, not corrected to sea level. That's what your manometer sees.
Altitude (pressure altitude) corrected for non standard temperature is called density altitude. Altimeter settings given in ASOS or AWOS reports, or by ATC, are most certainly NOT density altitude.

Perhaps we should start a new thread however, as this discussion deviates from the topic at hand.
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Last edited by krw5927 : 01-09-2014 at 10:14 PM.
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  #18  
Old 01-09-2014, 11:29 PM
BobTurner BobTurner is online now
 
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Quote:
Originally Posted by krw5927 View Post
Perhaps we should start a new thread however, as this discussion deviates from the topic at hand.
Agreed; PM sent.
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  #19  
Old 01-09-2014, 11:50 PM
SHIPCHIEF SHIPCHIEF is offline
 
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Simply put, a U tube manometer is the most accurate, simplest method to test your tank. Don't let the precision throw you off. It is so accurate that it is effected by room temperature and barometric pressure. No balloon and few gauges can approach it's accuracy.
The air volume in the column is slight, and leaks are shown very soon.
Let it sit a few days, and you will quickly get comfortable with the variations as they average out. This is amazing in it's low cost, simplicity, accuracy, safety and ease of use.
If you have good lungs, you can charge the fuel tank to 1 PSI, and almost naught more.
Tony Spicer's pictures tell all.
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  #20  
Old 01-10-2014, 07:45 AM
David-aviator David-aviator is offline
 
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Quote:
Originally Posted by SHIPCHIEF View Post
Simply put, a U tube manometer is the most accurate, simplest method to test your tank. Don't let the precision throw you off. It is so accurate that it is effected by room temperature and barometric pressure. No balloon and few gauges can approach it's accuracy.
The air volume in the column is slight, and leaks are shown very soon.
Let it sit a few days, and you will quickly get comfortable with the variations as they average out. This is amazing in it's low cost, simplicity, accuracy, safety and ease of use.
If you have good lungs, you can charge the fuel tank to 1 PSI, and almost naught more.
Tony Spicer's pictures tell all.
All true. But it does not show where the leak is if there is one.

The soapy water test with a little pressure will do that real quick.
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