What pressure in psi would be indicated by a properly calibrated absolute pressure gauge lying on a workbench at sea level not connected to anything?

A properly calibrated absolute pressure gauge measures the pressure relative to a perfect vacuum, meaning it accounts for the atmospheric pressure acting on the gauge itself. At sea level, the average atmospheric pressure is approximately 14.7 psi. Therefore, when a calibrated absolute pressure gauge is lying on a workbench at sea level and not connected to any system or process, it will indicate this atmospheric pressure value of 14.7 psi.

The gauge reads this value because it is designed to measure absolute pressure, which includes the atmospheric pressure acting on it. Since there is no other pressure applied to the gauge, the reading solely reflects the atmospheric pressure at that location. This understanding is fundamental in applications where distinguishing between absolute pressure and gauge pressure is essential, as gauge pressure is measured relative to atmospheric pressure, while absolute pressure is the total pressure measured from a vacuum.