[virgil283]

what kind of volume will a 3/4 inch diameter line flow at 1/2 lb. of pressure over, say, an hour? What's the energy content of that volume?...OK 3/4" sch40 pipe at say 50 foot length would be 151,000 btus/hour...as a rule of thumb gasoline is about 125,000 btus per liquid gallon and natural gas per liquid gallon would be around 75,000 btus

[thackney]

This allows 147,000 BTU/Hr. Within a couple percentage points, that is 147 standard cubic feet of natural gas.

I should have added, the manufactures web site linked above states the fill rate is 1.2 standard cubic meters per hour or 0.59 cubic feet per minute or 35.4 cubic feet per hour.