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AWWA C520:2019 pdf download.Knife Gate Valves, Sizes 2 In. (50 mm) Through 96 In. (2,400 mm)
Users are advised to refer to manufacturer's provided installation instructions. Knife gate valves are gaining their acceptance in the water and wastewater industry and as such are a significant component of any distribution, collection, and plant process system. Valve failures caused by improper installation, operation, and maintenance in these systems may result in damage, downtime, and costly repairs.
If it is not practical to store the valve indoors, protect the valve and actuators from weather, freezing, and the accumulation of water, dirt, rocks, and debris. When valves ftted with power actuators and controls are stored, energize electric actuators or otherwise protect electrical- control equipment to prevent corrosion of electrical contacts due to condensation resulting from temperature variations. Do not expose resilient seats to sunlight or ozone for any extended period. Always refer to manufacturers' specific storage instructions.
Ensure valve ends and seats are clean. Check all exposed bolting for loosening in transit and handling and tighten to manufacturer's recommendations. Open and close the valve to make sure it operates properly and that stops or limit switches are correctly set so that the valve seats fully. Close the valve before installing. It is strongly recommended that the instruction manual supplied by the manufacturer be reviewed in detail before installing knife gate valves.
Each valve should be operated through a full cycle and returned to its normal position on a time schedule designed to prevent a buildup of tuberculation or other deposits that would render the valve inoperable or prevent a tight shutoff. The interval of time between operations of large-diameter valves, valves in critical locations, or valves subject to severe operating conditions should be shorter than for other, less important installations but can be for whatever period has shown to be satisfactory based on local experience. The number of turns required to com plete the operation cycle should be recorded and then compared with permanent installation records to ensure full gate travel.AWWA C520 pdf download.