UL 565:2018-02-23 Liquid-Level Gauges for Anhydrous Ammonia and LP-Gas.
1.1 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.
1.2 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.
2.1.1 Except as indicated in 2.1.2, a component of a product covered by this standard shall comply with the requirements for that component. See Appendix A for a list of standards covering components generally used in the products covered by this standard.
2.1.2 A component is not required to comply with a specific requirement that:
a) Involves a feature or characteristic not required in the application of the component in the product covered by this standard, or
b) Is superseded by a requirement in this standard.
2.1.3 A component shall be used in accordance with its rating established for the intended conditions of use.
2.1.4 Specific components are incomplete in construction features or restricted in performance capabilities. Such components are intended for use only under limited conditions, such as certain temperatures not exceeding specified limits, and shall be used only under those specific conditions.
2.2 Units of measurement
2.2.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory or approximate information.
2.3 Undated references
2.3.1 Any undated reference to a code or standard appearing in the requirements of this standard shall be interpreted as referring to the latest edition of that code or standard.
2.4 Pressure and temperature rating
2.4.1 The rated service-pressure of a gauging device covered by these requirements shall not be less than 250 psig (1.7 MPa gauge).
2.4.2 Gauging devices covered by these requirements are intended for use at ambient temperatures within the range of minus 40°C — 55°C (minus 40°F — 55°F).
3.1 For the purpose of this standard the following definitions apply.
3.2 FIXED LIQUID LEVEL GAUGE — A liquid level indicator that uses a positive shutoff vent valve to indicate that the liquid level in a container being filled has reached the point at which the indicator communicates with the liquid level in the container.
Reproduced with permission from NFPA 58-2011, LP-Gas Code Handbook, Copyright ©201 0, National Fire Protection Association
3.3 LIQUEFIED PETROLEUM GAS (LP-GAS OR LPG) — Any material having a vapor pressure not exceeding that allowed for commercial propane that is composed predominantly of the following hydrocarbons, either by themselves (excluding propylene) or as mixtures: propane, propylene, butane (normal butane or isobutane) and butylenes.UL 565 pdf download.