Pressure gauges can measure either absolute pressure or gauge pressure, depending on the type of gauge being used. Let's explore the difference between the two:
Absolute pressure: Absolute pressure refers to the total pressure exerted by a fluid, including both the atmospheric pressure and the pressure exerted by the fluid itself. Absolute pressure is measured relative to a perfect vacuum, where zero pressure exists. An absolute pressure gauge measures the pressure relative to this vacuum reference point.
Gauge pressure: Gauge pressure, on the other hand, measures the pressure difference between the pressure being measured and the local atmospheric pressure. It disregards the atmospheric pressure and provides a reading relative to it. A gauge pressure gauge is designed to measure this difference and typically has the atmospheric pressure subtracted from the measured pressure.
To summarize, an absolute pressure gauge measures the total pressure, including atmospheric pressure, while a gauge pressure gauge measures the pressure difference relative to the local atmospheric pressure. It's important to note the type of pressure being measured and choose the appropriate gauge accordingly.