UL-565:2013 pdf free download – STANDARD FOR SAFETY Liquid-L evel Gauges for Anhydrous Ammonia and LP-Gas.
6 Bodies
6.1 A body or a part designed to be threaded into an opening in a container or designed for connection of piping shall have the required strength to withstand the normal stresses of installation and shall be constructed with a section to serve as a wrench grip.
6.2 A flange or other part of a body designed to be clamped in place when the gauge is installed shall have the required strength to withstand the stresses imposed by tightening the clamping screws or bolts.
6.3 Pipe threads shall be in accordance with the Standard for Pipe Threads, General Purpose (Inch),
ANSI/ASME B1.20.1.
Exception: Gauges intended for use in installations where pipe fittings incorporate other than NPT type threads shall be permitted to be provided with pipe threads complying with a national pipe thread standard compatible with those fittings. The pipe thread type shall be identified in accordance with 16.8.
7 Springs
7.1 A spring shall be guided and arranged to reduce binding, buckling, or other interference with its free
movement. When necessary, both ends of a spring shall be closed and squared.
8 Floats
8.1 A float designed to actuate a gauging mechanism shall have a buoyancy not less than 50 percent greater than that required to operate the mechanism, unless a counterbalanced arrangement is used.
8.2 A hollow float shall withstand an external crushing pressure of not less than 750 psig (5.2 MPa).
8.3 A float shall be secured to its corresponding lever, rod, or other part of the mechanism by a method that prevents the float from becoming detached under service conditions.
PERFORMANCE
9 General
9.1 Representative samples of each size and specific design of a gauge are to be subjected to the tests described in these requirements. Additional samples of internal parts, such as parts made of nonmetallic materials, may be required for separate tests.
9.2 A leakage test on a gauge is to use a source of aerostatic pressure such as air, nitrogen, or carbon-dioxide gas. A hydrostatic strength test is not prohibited from using water for developing the required pressure. All pressures are to be maintained 1 minute.
9.3 For the External Leakage and Hydrostatic Strength Tests in Sections 10 and 11, a positive shutoff valve and a pressure measuring device shall be installed in the pressure supply piping between the shutoff valve and the product under test.
9.4 Pressure measuring devices shall be calibrated over the range that it is used. The test pressure measured shall be not less than 20 percent nor more than 80 percent of the full-scale reading of the device.
Exception: The test pressure is allowed to be less than 20 percent or more than 80 percent of the full-scale reading of the measuring device, when calibration indicates that there is no loss of accuracy in the measured value.
10 External Leakage Test
10.1 A liquid-level gauge shall withstand, without leakage, an internal aerostatic pressure of 375 psig (2.6 MPa), or 1-1/2 times the rated service pressure, whichever is higher. The pressure is applied with the vent valve, if provided, in the closed position.
11 Hydrostatic Strength Test
11.1 A liquid-level gauge, exclusive of any float used therein, shall withstand, without rupture or permanent distortion, an internal hydrostatic pressure of 1250 psig (8.6 MPa), or 5 times the rated service pressure, whichever is greater.
11 .2 Samples of gauges previously subjected to the External Leakage Test, Section 10, are to be connected to a source of hydrostatic pressure.