That was a pretty chart on the Barton Recorder. The blue line was the static pressure(pressure of the pipeline) The red line was the differential pressure( pressure difference at the orifice). The guy said that they were using a .25" orifice. You take the temperature, static pressure, differential pressure, orifice plate size, and the pipe size and plug those into a formula and that is what gives you the amount of gas. It is not exact but you can usually figure the amount of gas in 1000 and multiply it by the price of gas on spot. Gas is sold by mmBTU so it won't be exact but it will be close.Gas closed at 3.82/mmBTU, so you can get an idea by saying $3.82 X 100mcf/day= $382 per day in gas sales. Again, not exact but close enough for us. It will be figuring it to the low side so we will actually have more money.