The AGA 3 and 8 Calculations reference atmospheric pressure. So does Directive 017 and API 21.1. But how exactly does it effect to gas measurement? If you refer back to your high school chemistry you will recall that base pressure is defined as 101.325 kPa. This is also the atmospheric pressure at sea level. When we refer to a volume of gas, it is always assumed to be at base conditions. (101.325 kPa and 15° C). As you move above or below sea level atmospheric pressure decreases or increases accordingly. Because most pressure sensors are not installed at sea level, we need to correct accordingly to ensure that a given volume is gas is always that volume, regardless of what the atmospheric conditions are.
So what effect does an incorrect atmospheric pressure correction have on gas volume? This post will outline two examples to illustrate the ramifications of an incorrect meter configuration. Read more