An airwatt or air watt is a unit of power very close to the watt which is used for various vacuum cleaning systems, such as vacuum cleaners. The airwatt is derived from English units. ASTM International defines the airwatt as 0.117354 * F * S, where F is the rate of air flow in ft3/m and S is the pressure in inches of water. This makes one airwatt equal to 0.9983 watts. [1]
The airwatt is useful measurement of vacuum power, since the power carried by a fluid flow (in the case of a typical house vacuum the fluid is air) is equal to pressure times volumetric flow rate. This could be a more useful figure than the electrical power drawn by the vacuum system's motor, since the efficiency of motor and vacuum systems varies.
| cleaning power (air watts) | = airflow (CFM) × suction (inches of water) / 8.5 |
| = airflow (m³/s) × suction (Pa) |