scope:

This part of ISO 16859 specifies methods for direct and indirectverification of test instruments used for determining Leeb hardnessin accordance with ISO 16859-1, and also describes when these twotypes of verification are to be performed. The direct verificationinvolves checking that individual instrument performance parametersfall within specified limits, whereas the indirect verificationutilizes hardness measurements of reference test blocks, calibratedin accordance with ISO 16859-3, to check the overall performance ofthe instrument for testing in the direction of gravity. Theindirect method can be used on its own for the periodic performancechecking in service.