As part of my back yard project, I plan to build a BBQ Island with a medium sized BBQ. The BBQ I have tentatively selected requires about 65000 BTU's. My house has a 1/2" gas stub sticking out of the back of the house and need to know if this will provide the required amount of gas. I asked the home builder this question and they were clueless.
I went to the web and found charts that have flow for various pipe sizes and length. The charts tell me that a 1/2" pipe will flow 119 cubic feet per hour (CFH) at 20ft and 82 cubic feet per hour at 40ft. Part of the problem is that I don't know how long the 1/2" pipe is inside the wall before it changes to a 3/4".
Without the required data I thought it might be best if I just measured the flow. It turns out my gas meter has dials for 1/2 cubic foot and 2 cubic foot flow. For my test I just opened the valve all the way and measured the flow. I measured 3 cubic feet in 33 seconds. It was a nice windy day so I wasn't too worried about releasing the gas into the air. My measurement yields 327 CFH. Since natural gas has about 1000 BTU's per cubic foot it appears that my pipe flows was more than enough to run my desired BBQ, however, the chart for 1/2 pipe only show 174 CFH at 10 ft. So makes me suspicious of my technique.
To test my technique I took a measurement with only the hot water heater running and compared my result to the data plate on the heater. It matched almost perfectly.
Is it possible that a 1/2 pipe can flow 327 CFH? Maybe there is a 3/4" line just inside the wall and the 1/2" is just the stub out. Are there any other means to test my flow?
I normally would have asked this question at the BBQ Galore forum but it's been down for a while.