Return to original calculation
for 0.25 mBar reduction in 20mB over 2 minutes
11m of 22mm pipe and 9m of 15mm pipe, no known dead runs.volume of that pipe between meter and appliances 5,800,000 cu mm = 354 cu ins = 0.2 cu ft Volume of whole gas meter = 5x7x8 inches =.16 cu ft
Therefore maximum vol = .36 cu ft
By Boyle's law drop in pressure of 0.25/20 = 1/80 means an increase in volume (the leak) of 1/80 so 0.36/80 = 0.0045 cu ft in 2 minutes = 0.135 cu ft per hour well above 0.01 cu ft / hour let alone 0.003 cu ft per hr read on the watch dial pointer of the meter
Pilot light consumption about 0.5 cu ft / hour so 3 times the minimum resolvable amount in the soundness test. So manometer test determines a leak of gas of degree 1/3 of a pilot light or more. I'll settle for that unless anyone knows the consumer side volume of a gas meter .