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why pressure gauge not available in CO2 fire extinguishers ?
compression of Gases needs their own flow according to molecule velocity and pipe or opining gagge
CO2 fire extinguishers do not have pressure gauges, as the gas is condensed in the cylinder. The only way to assess if a CO2 fire extinguisher is empty is to weigh it
CO2 extinguishers don't have gauges as they self pressurise (by the boil off of liquid CO2 into CO2 gas in the ullage space) as oppose to being separately pressurized by a Nitrogen over gas and as a result remain at constant pressure until all the liquid CO2 has gone, so a gauge wouldn't tell you anything!
CO2 in a fire extinguisher has it's own vapour pressure. Which in a closed unit like a fire extinguisher is about 750 to 800 psi at 70 degrees F. So basically if there is ANY CO2 present, you have pressure. You really don't need the gauge. You can check to see if the unit is full simply by checking it's weight.
I'm pretty sure you saw them placed in racks outside of a SCE room, no gages but are piped to a system. Well the tree top answers are all correct. The gauge will not tell you if they are empty or not so why install them.
