UL-753:2013 pdf free download – STANDARD FOR SAFETY Alarm Accessories for Automatic Water-Supply Control Valves for Fire Protection Service.
12 Operating Mechanisms
12.1 Shafts or bearings and matenais in contact with bearings for movable parts shall be of corrosion resistant materials and shall be either self-lubricated or provided with other means to accomplish lubrications for an extended period of time. Any lubricants employed shall be practical for use over a temperature range of minus 40 to 120°F (minus 40 to 48.9°C).
12.2 Metal parts coming in contact with a diaphragm shall have no sharp edges, burrs, or projections that might chafe or abrade the diaphragm.
12.3 An operating spring shall be made of corrosion resistant materials, and shall be retained and arranged to prevent abrasion, binding, buckling, or other interference with its free movement.
13 Water Motors
13.1 A water motor body shall have a 3/4 inch (19.05 mm) nominal pipe size tapped opening for a water supply connection and a tapped opening for a water drain connection. The smallest cross-sectional area of the discharge or water drain system and connection shall be not less than 50 times the cross-sectional area of the combined nozzles or jets.
13.2 A water motor body, or the piping immediately adjacent to a water motor body, shall be provided with
a sump or chamber to catch and retain foreign matter that might otherwise be carried to the nozzles or
jets by flowing water. Such a sump or chamber shall be provided with a plugged opening for cleanout and
drain purposes.
13.3 Shafts or shaft bearings employed in a water motor and gong assembly shall be self-aligning or otherwise arranged to provide for continuing operation of the gong when the parts of the assembly are installed on uneven supporting surfaces.
14 Gong and Gong Protection
14.1 An alarm shall be provided with a device that affords protection to the operating mechanism from the weather and that excludes nesting birds and vermin. This device shall be mounted with relation to the gong so that the sound of the gong will not be muffled due to misalignment of the device during mounting or settling of the structure supporting the gong assembly.
14.2 Ferrous material employed for gong protection devices shall be protected from corrosion to at least the extent afforded by a paint coating. If polymeric material is used, it shall be resistant to the effects of temperatures within the range of minus 40 to 150°F (minus 40 to 65.6°C) and to the effects of sunlight, excluding effects of color.
14.3 A gong striker, supporting head, and any pins or fasteners used in the striker assembly shall be of brass or other material having equivalent corrosion resistance. The arrangement shall be such that corrosion of adjacent parts or the effects of weather will not interfere with the operation of the mechanism.
15 Strainers
15.1 A strainer with nominal 3/4 inch (19.05 mm) pipe threaded connections shall be furnished with each water motor for installation in the pipe line serving a water motor, to protect the nozzles or water motor jets. Instructions shall be furnished with each water motor and shall direct that the strainer be located as close as practical to the outlet of the retarding chamber, or outlet from the alarm valve if no retarding chamber is used. The total cross-sectional area of the openings in the strainer screen shall be not less than 20 times the cross-sectional area of the combined nozzle orifices or jets, and the largest dimension of the screen openings shall be 1/32 inch (0.8 mm) less than the diameter of the smallest nozzle orifice. The screen shall be made of brass or other material having equivalent corrosion resistance.