[Code of Federal Regulations] [Title 46, Volume 1] [Revised as of Octobery 1, 2004] From the U.S. Government Printing Office via GPO Access [CITE: 46CFR30.10-55] [Page 387] TITLE 46--SHIPPING CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PART 30_GENERAL PROVISIONS--Table of Contents Subpart 30.10_Definitions Sec. 30.10-55 Pressure vacuum relief valve--TB/ALL. The term pressure vacuum relief valve means any device or assembly of a mechanical, liquid, weight, or other type used for the automatic regulation of pressure or vacuum in enclosed places.