a pressure gauge and a compressor or tire pump. is anything connected to it? you shouldnt pump it up for testing with any appliances hooked up you can ruin the inlet valves on them from too much pressure. do you have access to all the piping?
15 minutes isn't long enough if you're pressure testing to 10 or 15 psi. atmospheric conditions might make it fluctuate, but on that pressure i would be doing it over night. Better to test to 7 kpa using a low pressure gauge, as it will show up small leaks where as a high pressure test won't. Even better still would be to get a gas fitter who knows what they're doing, considering you're dealing with something that has the potential to cause severe damage, injury or death.
Code minimum is 15psi for 15 minutes with a minimum 3" gauge (assuming its for a gas line that is 2psi or less and under 200 feet). Most fitters I know, including myself, will test at 30psi for at least 24 hours.
Testing at 7kpa, even with a low pressure gauge, will NOT help you find small leaks. This is just plain bad advice. Seven kpa is only one psi, and many new residential gas installs are 2 psi (14kpa). Use at least 15 psi, with the proper gauge (3", exceeds test pressure by 15%, but not more than 300%, increments no more than 2 psi or 2% of the maximum dial reading, whichever is less). I've seen gas lines drop a pound or two and hold. You could probably hold 1 psi without using any pipe dope. Do it proper, or don't do it at all!!!
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