Specifies a method for testing components which use gases to enable their flow-characteristics under steady-state conditions to be compared. Specifies also requirements for the test installation, the test procedure, and the presentation of results. Accuracy of measurement is divided into two classes (A and B) which are explained in annex A. General background information is given in annex B, and the basic theoretical equations are given in annex C. Guidance as to the use of practical units for the presentation of results is given in annex D.