UL 1:2017 pdf free download – STANDARD FOR SAFETY Flexible Metal Conduit.
PERFORMANCE
10 Zinc Coating
10.1 The zinc coating on steel conduit shall meet all of the following requirements:
a) A specimen of the zinc-coated strip tested before forming shall not show a bright, adherent deposit of copper on any surface, including edges, after two 60-second immersions in a solution of copper sulphate.
b) A specimen of partially uncoiled conduit from finished conduit:
1) Shall not show a bright, adherent deposit of copper after one 60-second immersion
in a copper sulphate solution, and
2) Shall not show a bright, adherent deposit of copper on more than 25 percent of any
surface, including edges, after two 60-second immersions in a copper sulphate solution.
10.2 The copper sulphate solution is to be made from distilled water and the American Chemical Society (ACS) reagent grade of cupric sulphate (CuSO4). In a copper container or in a glass, polyethylene, or other chemically nonreactive container in which a bright piece of copper is present, a quantity of the cupric sulphate is to be dissolved in hot distilled water to obtain a solution that has a specific gravity slightly higher than 1.186 after the solution is cooled to a temperature of 18.3°C (65.0°F). Any free acid that might be present is to be neutralized by the addition of approximately 1 gram of cupric oxide (CuO) or 1 gram of cupric hydroxide [Cu(OH)2] per liter of solution. The solution is to be diluted with distilled water to obtain a specific gravity of exactly 1.186 at a temperature of 18.3°C (65.0°F). The solution is then to be filtered.
10.3 At one end of a sample length of finished steel conduit, the conduit is to be unwound from the outside to expose both edges and the inner surface of the formed strip and to facilitate working cheesecloth between the turns onto the inner surface to dry that surface during the test. To reduce the damage to the zinc coating, the strip is not to be straightened as it is unwound but is to remain in the helical form with a diameter no larger than three times the conduit diameter. Three 6-inch (150-mm) — axial measurement — specimens are to be cut from the partially uncoiled conduit. Additionally, three straight 6-inch (150-mm) specimens are to be cut from a sample length of the zinc-coated steel before forming.
10.4 With prudent attention to health and fire risks, the six specimens are to be cleaned with an organic solvent. Each specimen is to be examined for evidence of damage to the zinc coating during specimen preparation (not during forming). Only specimens that are not damaged are to be selected for use in the test. One specimen of the unformed strip and one specimen of the conduit are to be tested.
10.5 The two selected specimens are to be rinsed in water, and all surfaces are to be dried with clean cheesecloth. As much water as possible is to be removed in the drying operation, because water slows the reaction between the zinc and the solution and adversely affects the test results. The surface of the zinc is to be dry and clean before a specimen is immersed in the copper sulphate solution. The specimens are not to be touched by hands or anything else that can contaminate or damage the surfaces.