tank testing

originally replied to a ballast question
first pressure the tank with 8 foot head test it as they do life rafts that is with hose in loop, , with shut off valve in the tank fill hose loop with water, clear hose, , put air in ,,watch water level rise to top of hose, do not let water pass botton of hose of one side, or will blow out of other, , shut of air, then watch level in hose IF water level drops the tank or keel is leaking this is the ONLY way to ensure you have no leaks
When we build to survey this is mandetory, and the surveyer comes out to inspect the level!!
then once you have sealed, you will have no probs, with steel punching chuck in some used transformer oil from the power company, with lead if sealed you are ok
this method will show even a tiny pinhole, on a hot day the water will rise, at night will cool and drop, watch water over at least an hour, more for big tanks
in the sketch the levals are same, but the water needds be higher, up to 8 feet in the hose to the right of pic, from memory 8 head water is abt 2 psi, I know someone will come up with the exact figure)

 

You are right with 8 feet of water column, which is about 2 meters of water column. Test pressure should be 3 psi, or 0.2 bar.