Definition: The reduction in refrigeration system capacity due to lower atmospheric pressure at high altitudes. Compressor-based refrigeration systems lose approximately 3% capacity for every 300m of elevation above sea level.
Why It Matters: Johannesburg (1,750m altitude) requires transport refrigeration units (TRUs) to be sized 15-20% larger than equivalent sea-level operations. Cape Town operations (sea level) don’t experience this derate. Failure to account for altitude is the most common cause of refrigeration system failure in Gauteng.
Calculation:
- Johannesburg (1,750m): ~18% capacity loss
- Pretoria (1,330m): ~13% capacity loss
- Bloemfontein (1,395m): ~14% capacity loss
Related Terms: Compressor Capacity, Thermal Load, TRU Sizing, Absolute Pressure
Learn More: Thermal Load Calculator (altitude-compensated)
Find Suppliers: TRU dealers in Gauteng (altitude-rated equipment)