本文件建立了由额定功率为0125千瓦及以上的电机驱动的所有风机类型的风机效率分类系统。仅适用于驱动风机，但不适用于可能安装驱动风机的系统（成品原始设备制造商的产品，例如箱式风机和屋顶风机或通风系统）。本文件描述了对风机效率进行分类或应用最低效率限值（MEL）的许多不同程序。这些程序在:-ISO 12759-3；-本文件（ISO 12759-4）；-ISO 12759-5；-ISO 12759-6标准。没有描述将这些分类与MEL分类进行比较的方法。

This document establishes a system for the classification of fan efficiency for all fan types driven by motors of nominal rating 0,125 kW and above. It applies to driven fans only, but not to the system (finished original equipment manufacturer's product, for example box fans and roof fans or ventilation system) in which they might be installed. This document describes a number of different procedures to classify the efficiency of a fan or to apply a minimum efficiency limit (MEL). Those procedures are described in: — ISO 12759-3; — this document (ISO 12759-4); — ISO 12759-5; — ISO 12759-6. There is no method described to compare these classifications and MEL's.