How to test for leaks with nitrous bottle? Any recalls on bottles?

[NotchJohnson]

hey man, i have a zex bottle, and it did leak on me one time. im not too sure about the nos bottles, but my bottle has a hard plastic o-ring to seal between the bottle neck and the valve. I had some guy at the track fill it up, and he said it blew the o-ring. i was pissed because i only had it filled once before. i emptied it completely and checked the o-ring, it looked fine. i placed it back in there, tightened it up, and it hasnt given me a prob since. one way to test it besides just listening could be weighing it if you dont have a pressure guage. put it on a digital scale , then weigh it again later. good luck bro - John