[Code of Federal Regulations] [Title 42, Volume 1] [Revised as of October 1, 2004] From the U.S. Government Printing Office via GPO Access [CITE: 42CFR84.53] [Page 517] TITLE 42--PUBLIC HEALTH CHAPTER I--PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES PART 84_APPROVAL OF RESPIRATORY PROTECTIVE DEVICES--Table of Contents Subpart F_Classification of Approved Respirators; Scope of Approval; Atmospheric Hazards; Service Time Sec. 84.53 Service time; classification. (a) Respirators described in subparts H through L of this part shall be classified, where applicable, as approved for use during the following prescribed service times: (1) Four hours; (2) Three hours; (3) Two hours; (4) One hour; (5) Forty-five minutes; (6) Thirty minutes; (7) Fifteen minutes; (8) Ten minutes; (9) Five minutes; or (10) Three minutes. (b) Other service times may be prescribed by the Institute.