UL 132:2018-01 Safety Relief Valves for Anhydrous Ammonia and LP-Gas.
1.1 These requirements cover pressure and safety relief valves and hydrostatic relief valves for anhydrous ammonia and liquefied petroleum gas (LP-Gas) for use on containers built in accordance with ASME Pressure Vessel Code, Section VIII, Division 1 in nonrefrigerated systems in facilities covered by the following standards:
a) Requirements for the Storage and Handling of Anhydrous Ammonia, (ANSI K61.1), ANSI! CGA G-2.1.
b) Liquefied Petroleum Gas Code, NFPA 58.
c) Utility LP-Gas Plant Code, NFPA 59.
1.2 These requirements do not apply to relief valves for use on cylinders constructed in accordance with Department of Transportation (DOT) specifications.
1.3 The suitability of an accessory in combination with a relief valve shall be judged under the applicable requirements of this standard and NFPA 59.
1.3 added January 12, 2018
2.1.1 Except as indicated in 2.1.2, a component of a valve covered by this standard shall comply with the requirements for that component.
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b) Is superseded by a requirement in this standard.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.
3.0 ACCESSORY — Devices or components of a relief valve intended to provide a specific function under NFPA 59.
3.0 added January 12, 2018
3.1 FLOW CAPACITY (Measured Relieving Capacity) — The flow capacity of a safety valve measured at the flow-rating pressure, expressed in cubic feet per minute of air at a temperature of 15.6°C (60°F) and at a pressure of 14.7 pounds per square inch absolute (psia).
3.2 PRESSURE, BLOWDOWN — The value of decreasing inlet static pressure at which no further discharge is detected at the outlet of a safety valve of the resilient-disc type after the valve has been subjected to a pressure equal to or above the popping pressure.
3.3 PRESSURE, FLOW RATING — The inlet static pressure at which relieving capacity of a safety valve is measured for rating purposes.UL 132 pdf download.