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UL 2239-2019 pdf free download
UL 2239-2019 pdf free download.Hardware for the Support of Conduit , Tubing , and Cable.
6.2.5 Unless indicated by manufacturer’s instructions, a bofthead screw and nut combination other than direct bearing, and not having provision for tightening with a screwdriver, shall be tightened using a torque of 18.1 N.m (160 lbf-in).
6.3 Metallic coating thickness test
6.3.1 The test described in Clauses 6.3.2 — 6.3.9 shall be used to determine the thickness of a zinc coating where a minimum thickness is required.
Use of a nondestructive test method to determine the thickness of a zinc coating is not prohibited. Whenever referee measurements are required, the test described in Clauses 6.3,2 — 6.3.9 shall be used,
6.3.2 The solution to be used for the test shall consist of distilled water containing 200 g/L of reagent grade chromic acid, Cr03, and 50 g/L of reagent grade concentrated sulfuric acid, H2S04. The latter is equivalent to 27 milL of reagent grade concentrated sulfuric acid, specific gravity 1.84, containing 96 percent of H2S04.
6.3.3 The test solution shall be contained in a glass vessel such as a separatory funnel with the outlet equipped with a stopcock and a capillary tube having an inside bore of 0.64 mm (0.025 in) and a length of 140 mm (5.5 in). The lower end of the capillary tube shall be tapered to form a tip. the drops from which are close to 0.05 milliliter each. To preserve an effectively constant level, a small glass tube shall be inserted in the top of the funnel through a rubber stopper, and its position shall be adjusted so that, when the stopcock is open, the rate of dropping is 100 ± 5 drops per mm. An additional stopcock shall be used in place of the glass tube to control the rate of dropping.
6.3.4 The test shall be conducted at a room temperature of 21.1 — 32.2 °C (70— 90 °F). The sample and the test solution shall be kept in the test room until the temperature of the room, which shall be recorded, is attained.
6.3.5 Each sample shall be thoroughly cleaned before testing. All grease, lacquer, paint, and other nonmetallic coatings shall be removed completely by means of solvents. The samples shall then be thoroughly rinsed in water and dried with clean cheesecloth. Care shall be exercised to avoid contact of the cleaned surface by the hands or any foreign material.
6.3.6 The sample to be tested shall be supported 17.8 — 25.4 mm (0.7 — 1 in) below the orifice, so that the drops of solution strike the point to be tested and run off quickly. The surface to be tested shall be inclined close to 45 degrees from horizontal.
6.3.7 After cleaning, the sample to be tested shall be put In place under the orifice. The stopcock shall be opened and the time in seconds shall be measured with a stopwatch until the dropping solution dissolves the protective metallic coating, exposing the base metal. The end point is the first appearance of the base metal, recognizable by a change in color at that point.UL 2239-2019 pdf free download.
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