Compressed air glossary
Definitions of FAD, PDP, bar(a), bar(g), VSD, TCO, PSA and other terms used in compressor selection.
- FAD
- Compressor delivery referred to specified inlet conditions. When comparing models, check the test method and reference conditions in the documentation.
- bar(a) / bara
- Absolute pressure measured relative to a vacuum. Used in thermodynamic calculations.
- bar(g) / barg
- Gauge pressure relative to local atmospheric pressure. Absolute pressure equals gauge pressure plus atmospheric pressure.
- PDP
- Pressure dew point: the temperature at which water vapour starts to condense at a specified pressure.
- VSD / VFD
- Variable-speed drive using a frequency converter. Assess energy consumption against the load profile and the specific machine performance.
- TCO
- Total cost of ownership over a selected period. DAUCORE sums selected purchase, energy, spare parts and service costs.
- Air receiver
- A vessel that stores compressed air. Sizing considers pressure range, flow and demand duration.
- Moisture separator
- A device that separates liquid droplets. It does not replace a dryer for removing water vapour.
- Nm³
- Gas volume referred to specified normal conditions. Always state the reference temperature, absolute pressure and humidity.
- PSA
- Pressure swing adsorption. Used, among other applications, for air separation in nitrogen and oxygen generators.
- Oil-free
- A design without oil injection into the compression chamber. Specify point-of-use air quality requirements separately.
- kW / kWh
- kW is power; kWh is energy. Electricity cost depends on energy use and tariff, not motor power alone.