- Gas measurement: what’s the difference between Standard and Normal? It’s simply the reference conditions. Standard and Normal are different though depending which country you’re in and what industry it’s applied to. However, if you know the reference conditions eg 0°C and 1 bar then everything can be calculated. Mass flow of gas is often expressed as standard
Perhaps this is obvious but you need an idea about what your flow rate might be to size the meter correctly. Not only the maximum and minimum but also the normal flow rate expected. Maybe there will be a unique flow rate at start up?