UL-2127:2012 pdf free download – STANDARD FOR SAFETY Inert Gas Clean Agent Extinguishing System Units.
11 Pressure Relief Devices
11.1 Storage containers and applicable manifold and pilot relief devices shall be provided.
12 Gaskets and “0” Rings
12.1 A gasket of an elastomeric material shall be thick enough to provide a compression-type seal. A seal, gasket, or an “0” ring that is continuously exposed to the extinguishing agent under pressure during intended service shall be made of a material compatible with the extinguishing agent. See Elastomeric Parts Test, Section 49, and One-Year Time Leakage Test, Section 32.
13 Pressurization Level and Filling Volume
13.1 The pressurization level and filling volume shall be specified by the manufacturer.
14 Pressure Gauges
14.1 An extinguishing system unit shall be provided with a means to indicate the internal pressure of the storage container with a pressure gauge indicating the pressure in the chamber. The operating range of the gauge shall take into account the operating temperature-pressure relationship of the extinguishing system unit, except that the minimum operating pressure line is able to be higher than the pressure that corresponds to the minimum operating temperature.
14.2 In addition, the manufacturer shall reference in the Installation, Operation, and Maintenance Instruction Manual, the use of a test gauge at a frequency specified in NFPA 2001 to accurately measure the internal pressure of the storage container. The test gauge shall have an accuracy grade of 2A (0.5 percent of full scale) as specified in ANSI/ASME B40.1.
14.3 The pressure gauge face shall indicate the appropriate units for which the gauge is calibrated, such as psig, kPa, kg/cm2, or any combination of pressure units.
14.4 The maximum indicated gauge pressure on the pressure gauge shall be not less than 120 percent of the pressure at 120°F (49°C). The zero, operating, and maximum indicated gauge pressures shall be shown in numerals and with marks. The minimum use temperature shall be marked on the left side of the operable pressure range, a 70°F (21°C) temperature value shall be marked at indicated charging pressure and the maximum use temperature shall be marked on the right side of the operable pressure range. The portion of the arc between 95 and 110 percent of the charging pressure at 70°F (21°C) shall be indicated in green. The background of the gauge face in the area defined as being that above radial lines connecting each of the maximum and minimum markings to the center of the gauge shall be red. The arc of the dial from the zero pressure point to the minimum use temperature marking shall read “Recharge.” The arc of the dial from the maximum use temperature to the maximum indicated pressure shall read “Overcharged.” All numerals, letters, and characters shall be black and the remaining background of the gauge shall be white. Pointers shall be yellow, and the tip of the pointer shall end in the arc of the pressure indicating dots, and shall have a maximum tip radius of 0.010 inch (0.25 mm). The minimum length of the pointer from center point of the dial to the tip shall be 0.375 inch (9.53 mm). The minimum length of the arc from the zero pressure to the indicated charging pressure shall be 1 inch (25.4 mm) measured from the center line of the zero pressure mark to the center line of the indicated charging pressure mark.