Specifications include, but are not limited to: GENERAL The strainers shall be a motorized automatic self-cleaning type, Adams VWS-20, S P. Kinney Model A, or approved equal. The replacement strainers shall be drop-in units that require no piping changes or footprint accommodations. The strainers shall be of standard construction with exceptions as noted herein. Construction shall withstand pressures up to 150 psi. The strainers shall have 14-inch nozzles positioned as shown on the drawings, and field verified. They shall be capable of handling 4,000 gallons per minute (gpm) of secondary effluent at a working pressure of 90 psi. The strainers shall remove solids larger than 250 microns (.01-inch). Pressure drop across the strainer shall not exceed 2.0 psi at 4000 gpm with 25 percent of the straining surface clogged. The average percentage of backwash effluent shall be 1 percent of the strainer influent over a 24-hour period. Provide an inspection opening suitable for visual inspection of the straining media. ELECTRICAL The strainer shall be driven by a 1/2 hp, 460 volt, 3 phase, 6O Hz, AC, totally enclosed motor with worm gear reducer. If a starter is needed, one shall be provided to the motor. All electrical equipment shall conform to the current code. BACKWASH CONTROL SYSTEM An automatic backwash control system shall be furnished for intermittent actuation of the backwash cycle. The control shall consist of an eccentric ball valve actuated by an electric motor operator, timer, ON/OFF/AUTO control switch, backwash indicating light, pressure gauges, and an adjustable pressure differential switch, initially set to override the timer at 4 psig. The complete control package shall be provided by the strainer supplier. The panels shall be mounted as shown on the drawings and shall be NEMA 4 enclosures. INSTALLATION City staff will install the units and make all the connections. The City will coordinate with the manufacturer to approve and provide a certificate of proper installation.
