UL 132-2021 pdf download – Safety Relief Valves for Anhydrous Ammonia and LP-Gas.
13 General 13.1 Representative samples of a pressure-relief valve shall be subjected to the tests described in these requirements. Additional samples of internal parts, such as springs, seat seal material, and similar parts, may be required for separate tests. 13.2 All leakage and hydrostatic pressure strength tests are to be maintained for at least 1 min. 13.3 For a safety valve, three samples of each size, design, and setting shall be used for start-to- discharge and resealing pressure tests. This same set of samples shall be used for the flow capacity tests described in the Flow Capacity of Safety Valves, Section 19. No fewer than two successive start-to- discharge and resealing pressure observations shall be made on each of the test samples used for the tests described in Sections 18, 19 and 21. 13.4 For a hydrostatic relief valve, two samples of each size and design shall be used for start-to- discharge and resealing pressure tests. Flow capacity tests need not be conducted for this class of safety valve. No fewer than two successive start-to-discharge and resealing pressure observations shall be made on each of the test samples used for the tests described in Start-To-Discharge/Resealing Pressures of Hydrostatic Relief Valves, Section 22. 13.5 The test conditions may be limited to the service conditions for which a safety valve is intended, such as the fluid handled and the pressure of the fluid. 13.6 An accessory that is provided with, or recommended by the manufacturer for use with, a relief valve shall comply with the performance requirements of this standard.
15 External Leakage Test 15.1 A pilot valve or accessory shall be free from leakage through stem or body seals or other joints, and shall not show evidence of porosity in castings when tested as described at any aerostatic pressure between 0 and 1-1/2 times the highest set pressure of the valve. 15.2 During this test, the sample shall be connected to a source of aerostatic pressure. A positive shut- off valve and a pressure-measuring device shall be installed in the pressure supply piping. The pressure- measuring device shall be installed between the shut-off valve and the sample under test. While under the applied test pressure, the sample shall be submerged in water to detect leakage, or all joints and body casting surfaces are to be brushed with a soap and water mixture or other leak-detection solution. 15.3 When the pilot valve or accessory does not incorporate a threaded outlet, a specially prepared sample shall be submitted with the outlet blocked or otherwise rendered inoperable. 15.4 Pressure measuring devices shall be calibrated over the range that they are used. The test pressure measured shall be not less than 20 % or more than 80 % of the full-scale reading of the device used. Exception: The test pressure is allowed to be less than 20 % and more than 80 % ofthe full-scale reading of the measuring device, when calibration indicates that there is no loss of accuracy in the measured value.