Division 1 Definitions for the purposes of Annex II

‘Inlet stagnation volume flow rate’ (q) is the volume of gas that passes through the fan per unit of time (in m³/s) and is calculated on the basis of the mass of gas moved by the fan (in kg/s) divided by the density of this gas at the fan inlet (in kg/m³).

‘Compressibility factor’ is a dimensionless number that describes the amount of compressibility that the gas stream experiences during the test and is calculated as the ratio of the mechanical work done by the fan on the gas to the work that would be done on an incompressible fluid with the same mass flow, inlet density and pressure ratio, taking into account the fan pressure as ‘total pressure’ (k_p) or ‘static pressure’ (k_ps).

k_ps means compressibility coefficient for the calculation of fan static gas power.

k_p means compressibility coefficient for the calculation of fan total gas power.

‘Final assembly’ means a finished or assembled on-site assembly of a fan that contains all the elements to convert electric energy into fan gas power without the need to add more parts or components.

‘Not final assembly’ means an assembly of fan parts, consisting of at least the impeller, which needs one or more externally supplied components in order to be able to convert electric energy into fan gas power.

‘Direct drive’ means a driving arrangement for a fan where the impeller is fixed to the motor shaft, either directly or with a co-axial coupling, and where the impeller speed is identical to the motor’s rotational speed.

‘Transmission’ means a driving arrangement for a fan which is not ‘direct drive’ as defined above. Such driving arrangements may include transmissions using a belt-drive, gearbox or slipping coupling.

‘Low-efficiency drive’ means a transmission using a belt whose width is less than three times the height of the belt or using some other form of transmission apart from a ‘high-efficiency drive’.

‘High-efficiency drive’ means a transmission using a belt whose width is at least three times the height of the belt, a toothed belt or using toothed gears.