Why are there two air gauges on a typical air compressor? A visitor that is new to air compressors sent in the question.
If you have used air compressors before, then you know why two air gauges on an air compressor is the norm. But what if you haven’t?
Tank Air Gauge
The typical air compressor has a tank into which the compressor pump pumps air to pressurize it. This tank typically has a gauge to display the pressure in the tank.
It is the tank pressure that the compressor pressure switch monitors as well, so it knows when to start or stop the air compressor motor, based on the pressure in the tank.
As the compressed air user, you need to know the pressure in the tank too, both to be sure that the air compressor is shutting off at the correct cut out pressure, and to know how much air you have available to you to work your air tools.
So, one of the two gauges on the air compressor is to display the tank air pressure.
The tank pressure gauge needle will display a lower pressure as the compressed air is being consumed, and the tank pressure displayed by the tank air gauge will increase fairly rapidly when the compressor motor cuts in to generate more compressed air.
Regulator Air Gauge
The other gauge on a typical air compressor is the regulator gauge. In the image below you see the regulator gauge extending towards you from the regulator body.
The regulator pressure gauge displays the pressure setting of that air regulator. This pressure setting is the air pressure which the user wants to send down the air line to the air tool.
Rule of thumb? Set the regulator pressure at the lowest PSI setting at which the air tool will run properly. This helps reduce air compressor cycling frequency (energy saver).
The regulator air gauge pressure display does not move a great deal (it typically bounces about 10 PSI as the air to the tool is turned on and off) unless the air consumed by the air tool is greater than the compressed air the compressor can generate. In this case the regulator gauge will display a steadily decreasing pressure.
Monitoring both gauges is useful for spotting irregularities when you are using your air compressor.