Definition: The total pressure exerted by a gas or fluid, measured relative to a perfect vacuum (zero pressure). Equals atmospheric pressure plus gauge pressure.
Why It Matters: Refrigeration systems operate based on absolute pressure differentials. At Johannesburg’s altitude (1,750m), atmospheric pressure is ~15% lower than sea level, affecting compressor performance and capacity calculations.
Formula: Absolute Pressure (kPa) = Atmospheric Pressure + Gauge Pressure
Related Terms: Gauge Pressure, Altitude Derate Factor, Compressor Capacity