jcarbon

Would like to hear some from the experts.

Lets see if my math is correct.

Lets say I have a 100 LB tank that should contain about 25 gallons of propane(divide LB /4) . If *1 gallon* = *91,500* BTU then I have 2,287,500 BTU (25 x 91,500).

**Is it correct that one must take out 20% from total BTU since tanks can only be filled to 80% capacity??

If the tank is rated correctly, then it should hold 100lbs of liquid LP @ 80% of tank volume. This is full. Check the tank label to clarify the capacity. The tank should hold the rated capacity and have the correct head space.

20lb tank: approx 18 lb empty ... 38 lbs full

100lb tank: approx. 68 lb empty ... 170 lbs full

The empty weight should be stamped on the side of the tank.

... Now some tank fillers claim the amount they can put into the tank is 100lb less 20%=80 lbs. This usually happens when the filler charge a set fee per tank. ... ie: the filler is cheating the consumer by charging for the gas he didn't put into the tank. ... where the filler charges by the weight he puts into the tank, this usually doesn't happen and if the tank still has some gas remaining the consumer doesn't pay for it again.

jcarbon ...

If so then I have 1,830,000 BTU in a 100 LB tank. ...

You should have 100 lb / 4.22 = 23.7 gal ... 23.7 X 91,500 = 2168550 btu

jcarbon ...

If I have 30,000 BTU burner then in theory I have 61 hours of use at full burn, correct?

It is not quit this simple. A lot depends on the outside temperature and if the tank was properly sized for the equipment being served. ... But assuming the outside temp is 60 deg F or higher, then you might get close to 70 to 72 hrs of burn time. ... A tank is not going to completely empty before pressure drops and the flame has problems. ... In cold or freezing temps, the tank might still contain 25% or more of its liquid gas.

jcarbon

...If I used them at 50% then I double the use time, correct?

correct, as long as all conditions are the same.

jcarbon ...

Is a 30,000 BTU burner the same as any 30,000 BTU burner or is there diferences?

As long as they are working at the proper gas pressure and flame/air mixture are correct, then they would be near the same.

jcarbon

Finally, most suggest 3/8 cooper line to burners. Is this best??

This is hard to answer. A lot depends on the length of pipe. 80ft of 3/8 copper can pass about 25,000 btu per hr. 10ft about 75,000 btu per hr.

So if you are talking about short connections from a supply manifold, then yes. But 200 ft across the yard to supply several heaters and a range, no. You need a gas pipe sizing chart.

http://www.engineeringtoolbox.com/propane-gas-pipe-sizing-d_827.html In most cases for short runs, the 3/8 copper would be ok. Most truck or trailer concessions are plumb with 3/4" dia manifold supply line and 3/8" copper pipe connection lines.

post edited by edwmax - 2013/08/23 15:35:29