TABLE OF CONTENTS In addition to the abbreviations used in SI, the following are employed in air conditioning work:
| db | Dry bulb temperature |
| wb | Wet bulb temperature |
| dp | Dewpoint temperature |
| rh | Relative humidity |
| ? | Percentage saturation |
| kg/kg | Kilograms water vapour per kilogram dry air (absolute moisture content) |
| TH | Total heat |
| SH | Sensible heat |
| LH | Latent heat |
| SHR | Sensible heat ratio |
| ON OFF | The condition of air or water entering or leaving a coil or heat exchanger |
| TR | Tons of refrigeration capacity |
| TRE | Tons of refrigeration capacity extracted |
| TRR | Tons refrigeration rejected (at final cooler) |
| HP | High pressure (refrigerant) |
| LP | Low pressure (refrigerant) |
| DX | Direct expansion cooling |
| AT | Temperature difference |
| ach | Air changes (room volumes) per hour |
| ahu | Air-handling unit |
| swg | Static water gauge |
| NR | Noise rating. One of a series of curves relating noise level and frequency to speech interference |
| NC | Noise criteria. Similar to NR, but differing, particularly at the low-frequency end |
The movement of air by fan, conveying outside air into the room or expelling air or both. Filtration, heating and control of the distribution pattern may be included. It is not cooling in the sense of temperature reduction but can be used to limit temperature rise when the outside air is below that of the space being treated.
This necessitates plant capable of control of temperature by being able to add or subtract heat...
