UL 793-2017 pdf free download

UL 793-2017 pdf free download.Automatically Operated Roof Vents for Smoke and Heat.
a) A coating of hot-dipped mill galvanized sheet steel complying with the coating Designation G60 (G90 for an enclosure that houses live parts) or A60 in Table I of the Specification for Steel Sheet. Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process. ASTM A6531A653M. with not less than 40 percent of the zinc on any side, based on the minimum single spot test requirement in the ASTM Designation. The weight of the zinc coating may be determined by any method, but in case of question shall be established in accordance with the test method in the Standard Test Method for Weight (Mass) of Coating on Iron and Steel Articles with Zinc or Zinc-Alloy Coatings. ASTM A90. An A60 (alloyed) coating shall also comply with the requirements in 6.4.
b) A zinc coating, other than that provided on hot-dipped mill galvanized sheet steel, uniformly applied to an average thickness of not less than 0.00041 in (00104 mm) on each surface with a minimum thickness of 0.00034 in (0.00864 mm). The thickness of the coating is to be established in accordance with the test method in the Standard Guide for Measurement of Electrodeposited Metallic Coating Thicknesses by the Dropping Test, ASTM 8555. An annealed coating shall also comply with the requirements in 6.4.
C) A cadmium coating not less than 0.0127 mm (0.0005 in) thick on both surfaces. The
thickness of coating is to be established in accordance with the test method in the Guide for
Measurement of Electrocteposited Metallic Coating Thicknesses by the Dropping Test. ASTM
8555.
d) Two coats of an organic finish of the epoxy or alkyd-resin type or other outdoor paint on each surface. The acceptability of the paint may be determined by its composition or by corrosion tests as specified in the Standard for Organic Coatings for Steel Enclosures for Outdoor Use Electrical Equipment. UL 1332.
6.2 Coated or uncoated metals used in the assembly of vents shall be galvanically compatible.
6.3 Component springs and bearings used in the assembly of vents shall be of material having resistance to atmospheric corrosion.
6.4 A hot-dipped mill galvanized A60 (alloyed) coating or an annealed zinc coating that is bent or similarly formed after annealing and that is not otherwise required to be painted shall be painted in the bent or formed area as specified in 6.1 (d) it the bending or forming process damages the zinc coating as described in 6.5.
6.5 It flaking or cracking of the zinc coating at the outside radius of the bent or formed section is visible at 25 power magnification, the zinc coating is to be considered damaged. Simple sheared or cut edges and punched holes are not considered to be formed. but rolled edges shall comply with the requirements in 6.4.UL 793-2017 pdf free download.