wvmarle:
Oh, you mean the gassy kind of gas (like propane or butane) rather than the liquid kind of gas (gasoline, petrol)?Then the pressure does NOT tell you the fill level. You'll have to weigh the tank, or after filling measure how much is taken out.
Yes i know it for some tank i can weigh for another i must use another thechnologie to do this, like install a
sensor between the gas line from the grill and the cut-off valve on the tank,if exist on arduino a sort of sensor for this technologie.