UL Standard for Safety Liquid-Level Gauges for Anhydrous Ammonia and LP-Gas (Sixth Edition; Reprint with revisions through and including February 23@ 2018)
These requirements cover liquid-level gauges for anhydrous ammonia and liquefied petroleum gas (LP-Gas) for use with pressure vessels in nonrefrigerated systems in installations covered by the following American National Standards and others: a) Compressed Gas Association@ CGA G-2.1. b) Liquefied Petroleum Gas Code@ NFPA 58. c) Storage and Handling of Liquefied Petroleum Gases at Utility Plants@ ANSI/NFPA 59. These requirements cover designs of gauges that require the release of liquid or gas phases of the contained fluid in order to function and gauges that do not require the release of liquid or gas phases of the contained fluid to function.