The purpose of the International Standard is to define specifically all requirements on tests and laboratory personal, test parameter and its precision and to give options for the testing procedures to be applied for carrying out performance tests on closing, non-reclosing and combined safety devices for protection against excessive pressure as specified in ISO 4126 Parts 1, to 10, with particular reference to type testing. Function and capacity tests of the valve shall be considered and inlet and outlet conditions shall be included. Back-pressure influence shall be considered, if necessary. Alternative test rig configurations measurement techniques as well as to testing procedures should be given as informative examples. Further topics to be considered must be low and high pressure applications.