This standard establishes a serise of seat leakage classes for control valves and defines the test procedures.Selection of a leakage class is not restricted as to valve design, but accaptable values for various commercially available designs are suggested for each class under Section 4.The standard cannot be used as a basis for predicting leakage at conditions other than those specified.The standard does not apply to control valves with a rated C less than 0.1.