My welded aluminum wing tanks have identical dimensions, but one holds 8.3 gallons and the other holds 7.9. The machine shop that constructed the tanks used 30 psi air to leak test and permanently bulged the top and bottom (formerly) flat plates. Uneven bulges make the difference in capacities. At home I used my lung power to supply compressed air through my home made manomometer. Mark Langford has manomometer construction and usage on his web site. I found 7 additional leaks using dish detergent that the machine shop had missed. The leaks were re-welded with no further issues. Fortunately the bulged tanks still would fit in the intended wing locations.
Sid Wood Tri-gear KR-2 N6242 Mechanicsville, MD, USA --------------------------------------------------------------- > So here I am, finished my wing tanks and very proud of the welding work. > Somebody mentioned that I should pressure test the tank to ensure it is > leak > free. I usually take good advice to heart, so I hooked up the compressor, > blocked off all the inlet, breather and other openings, prepared the > little > water spray can and started the compressor. Slowly I start pressing the > lever on the gun and start spraying the seams with water to see if I > detect > any bubbles. Finally I found a corner with a fine mist. I couldn't see > exactly where this offending pinhole is and I increased the pressure a bit > whilst spraying some more water on the offending seam. After about 3-4 > minutes of this adding pressure then spraying water and closely watching > for > the mist, I heard a "clunk" sound. Ignoring the sound (I am not stupid I > know the tank will move a bit with pressure inside) I concentrate on this > point on the seam and another two "clunks" further I finally pinpoint the > pinhole. > > Pierre ------------------------------ > Thank you for being so brave and sharing this lesson with all of us. > > Had you added a small portion of dish washing detergent to the water you > could have got away with just a PSI or two. > > We used to use it in the airforce to detect oxy leaks and tradies use it > to > detect gas leaks in home/caravan systems. > > Paul. > > -----Original Message----- > > prepared the little water spray can and start spraying the seams with > water > to see if I detect any bubbles. --------------------------------------------------------- > > Just FYI anyone who needs to test your fuel tank for leaks. Vans (RV) > sells > a kit for doing this and it involves a balloon attached to a valve. You > put > in just enough air to get the balloon to expand. Then if it does not > deflate, you are good to go. If it does, you don't need any more pressure > than to keep the balloon inflated and you spray a soap/water solution as > suggested, and look for the bubbles. The kit is cheap. > > Daniel R. Heath -?Lexington, SC
