AWWA C502-18 pdf download.Dry-Barrel Fire Hydrants
The selection of materials is critical for water service and distribution piping in locations where there is likelihood the pipe will be exposed to significant concentrations of pollutants composed of low-molecular-weight petroleum products or organic solvents or their vapors. Documented research has shown that pipe materials such as polyethylene and polyvinyl chloride, and elastomers, such as those used in jointing gaskets and packing glands, are subject to permeation by low-molecular-weight organic solvents or petroleum products. If a water pipe must pass through a contaminated area or an area subject to contamination, consult with the manufacturer regarding permeation of pipe walls, jointing materials, etc., before selecting materials for use in that area.
4.5.4 Parts made of gray or ductile iron. The following parts of the hydrant may be made of either gray or ductile iron: barrel, bonnet, base, packing plate, gates and plates, and outlet-nozzle caps. Miscellaneous structural parts may be made of gray iron or ductile iron. Outlet caps for nonthreaded connections may be made of other materials provided these parts meet the requirements of Sec. 4.6.3.3. (See Table 2 for hydrant component parts.)
4.5.5 Operating mechanism torque limits. The design safety factor of the operating mechanism shall be not less than 5 and shall be based on the torque required for the closing and opening of the hydrant at a working pressure of 150 psig (1,034 kPa [gauge]). Hydrants shall be functional and capable of being opened or closed without difficulty following application of an operating torque of 200 lbf ft (270 N m) at the operating nut in the opening direction with the hydrant fully opened and the closing direction with the hydrant fully closed (see Sec. 5.2.2). The torque requirements apply only to hydrants of 5-ft (1.5-m) bury or less.
4.5.6 Traffic model components. Hydrants with frangible sections near the ground line designed to break on impact shall, except for the frangible components, conform to structural design requirements of this standard. Frangible components will not be required to meet the structural design safety factor of 5.AWWA C502-18 pdf download.