Definition: Pressure measured relative to atmospheric pressure. Most pressure gauges read gauge pressure (not absolute pressure).
Why It Matters: Refrigeration system pressures are typically shown as gauge pressure. At Johannesburg’s altitude, the same gauge reading represents lower absolute pressure than at sea level, affecting system performance calculations.
Conversion: Absolute Pressure = Gauge Pressure + Atmospheric Pressure
Related Terms: Absolute Pressure, Atmospheric Pressure, Altitude Derate Factor