Hey, so I need to get a portable air tank. I recently purchased one from princess auto, filled it up to about 110psi and by next morning it was down to 20. I returned it and am still looking. Is this normal or did I get a dud? Assuming that they're for emergency use it would seem stupid that they leak that much. I noted that alot of them seem to have the same valves on them so was hoping for some real world experience and advice.