This new edition is a periodic re-issuance to ensure that UL's Standards remain up-to-date with regard to format and editorial issues such as renumbering, repaginating, correction of editorial errors, correction of cross-references and updating titles of referenced Standards. Revisions to UL 252 reflect the discontinued use of cadmium plating in compressed gas regulator accessories and the replacement of ASTM No. 3 Swelling Oil with IRM 903 as stated in the bulletin dated April 9, 2003.