| | | | | |
| | Symbol | Designation | Unit | |
| | c | Flow speed | m/s | |
| | D2 | Impeller diameter | m | |
| | A | Cross-sectional area | m2 | |
| | g | Acceleration | m/s2 | |
| | n | Speed | rpm | |
| | P | | kW | |
| | pst | Static pressure | Pa | |
| | A pst | Static pressure difference | Pa | |
| | Pd | Dynamic pressure | Pa | |
| | A Pd | Dynamic pressure difference | Pa | |
| | Pt | Total pressure | Pa | |
| | AP | Total pressure difference | Pa | |
| | T | Temperature (Kelvin) | K | |
| | t | Temperature (Celsius) | °C | |
| | | Circumferential speed of the impeller (outside) | m/s | |
| | V | Airflow or volume flow | l/s or m3/h | |
| | Q. | Density | - | |
| | Tl | Efficiency | - | |
| | | Volume number | - | |
| | ¥ | Pressure number | - | |
| | C | Coefficient of drag | - | |
| | XR | Coefficient of friction of channel or pipe | - | |
| | Q. | Pipe diameter | m | |
| | | Equivalent diameter | m | |
| | l | Pipe or channel length | m | |
| | '-WA2 | Sound power level to surround | dB | |
| | '"WAS | Sound power level in tube on inlet side | dB | |
| | '"WA6 | Sound power level in tube on outlet side | dB | |
| | | | | |