ISO 12759-3:2019 pdf free
ISO 12759-3:2019 pdf free.Fans一Efficiency classification for fans一Fans without drives at maximum operating speed
rotary bladed machine which receives mechanical energy and utilizes it by means of one or more impellers fitted with blades to maintain a continuous flow of air or other gas passing through it and whose work per unit mass does not normally exceed 25 kJ/kg
Note 1 to entry: Fans are defined according to their test configuration, function, fluid path and operating conditions (see ISO 13349).
Fans range from the purpose-built single fan to the series produced certified ranges manufactured in large quantities. A fan may be an impeller on a shaft with no drive mechanism attached (fan without drive), Figure 1.
The variation in design has led to efficiency being defined in a number of ways to suit the demands of the fan type and the market place.
The following is a guide to the optimum efficiency (best efficiency point) levels that are achievable by the fan types addressed by this document. The minimum levels of acceptability are dependent on consultation between regulators and manufacturers’ representatives or local legislation where this exists.
The efficiency grade for a fan is based on its performance characteristics at maximum permissible rotational speed to obtain its best efficiency point.
A number of fixed efficiency grades are defined based on fan diameter and optimum efficiency.Formula (A.1) in Annex A defines an efficiency boundary as a function of impeller diameter.The fan belongs to a given efficiency grade if its efficiency at its best efficiency duty point is equal to or lower than the efficiency value calculated along its efficiency boundary for its grade, based on fan diameter, and above the value provided for the efficiency boundary calculated for the grade immediately below.
In simple terms a fan belongs to an FEG (e.g. FEG85) if its efficiency, at best efficiency duty and maximum speed, is below the curve according to its designation, but above the next curve beneath (e.g. FEG80).An example of how to calculate the efficiency grade is given in Annex A.ISO 12759-3 pdf free download.
