ISO 8426:1988

Specifies the methods for determining the derived capacity under steady-state conditions and at defined, continuously rotating shaft speeds. The unit may be tested as a pump, with mechanical energy applied to the shaft and hydraulic energy obtained at the fluid connections, or as a motor, with the hydraulic energy supplied to the fluid connections and mechanical energy obtained at the shaft. Accuracy of measurement is divided into three classes (A, B, and C) which are explained in annex A.