Abstract
The purpose of a fan characteristic is to delineate useful information regarding the performance of a fan in its installation. Specifically, the quantity-head characteristic shows the quantity of air delivered against a certain resistance in the intended installation. The authors discuss the set up of four basic arrangements of fan types and installations, and describe three currently used fan-head definitions. The definitions of fan head are evaluated, the fan head being defined as the discharge static head minus the inlet total head. A primary arrangement of each type of fan is described and a single primary quantity-head characteristic for each type of fan is defined. If a fan is installed in any arrangement other than its primary one, the primary characteristic cannot be assumed to apply, but a separate test must be conducted to determine its characteristic in its intended arrangement. Results of complete tests of a fan installed in its four possible arrangements are given to illustrate the principles which are set forth.
