All experimental testing shall be performed following the procedures of ISO 5801. It should be noted that in scaling the performance, the efficiency likely to scale is the impeller efficiency. Allowance shall therefore be made for drive and transmission efficiencies when deriving the impeller efficiency.Having measured the performance of the selected fans, the performance may be non-dimensionalized in terms of the non-dimensional flow coefficient ϕ, pressure coefficient ψ, power coefficient λ, and the efficiencyη.