What does the letter M in the pressure gauge PM on the gauge chart mean?
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It’s usually PG and PI; I don’t know what PM is :(
Haven’t encountered it yet: Q, powerless
On the acetylene generator, it’s the local pressure gauge
The manual on common instruments explains that when M is used as a modifier letter, it denotes an instantaneous value. It is also stated that if the first letter of the variable being measured is combined with any one of the modifier letters D (difference), F (ratio), M (instantaneous), K (rate of change), or Q (accumulation), it indicates a different meaning for that variable. Therefore, the combination of the letter representing the variable and the modifier letter should be considered as a whole; for example, TDI and TI refer to temperature difference indication and temperature indication, respectively. These modifier letters are used only in specific situations. So, personally, does it mean an instantaneous pressure gauge? ?
PI stands for pressure indication, which is generally the pressure value displayed by a DCS. PG refers to a pressure gauge installed locally. As for what PM means, I haven’t encountered it before; could it refer to a vacuum pressure gauge (since many models of vacuum pressure gauges start with PM)?