Sand Media Filter

The automatically controlled system will operate on line for extended periods of time prior to the short backwashing cycle. Automatic filter operation is monitored on both elapsed time as well as pressure differential. When the controller “calls” for a backwash as a result of pressure differential or elapsed time, the backwashing function utilizes a portion of the clean filtered water produced by the system to clean the media. The backwash flow is segregated for proper disposal in a separate discharge line. Note that single tank systems utilize unfiltered water for backwashing. Optional external backwash water sourcing systems are available for both single and multiple tank systems.

FILTRATION PROCESS

• The contaminated water enters the tank through the inlet manifold, transitioning to the Yardney 3-way valve and into the top inlet of each tank
• The Yardney two-stage deflector creates a uniform distribution for laminar flow across the media bed while avoiding channeling of the media bed
• Particulate is trapped and retained within the media bed resulting in clean process water flowing out through the stainless steel wedgewire underdrain, to the outlet of each filter tank and to the outlet manifold for end use

Superior filter performance is achieved by the added features of a larger inlet, two-stage deflector, 14″ media bed depth, gravel pack and a hydraulically balanced underdrain to produce a low pressure drop which will produce longer run times between backwashes.

BACKWASH PROCESS

• Backwash sequence is initiated by either elapsed time of the Yardney controller or pressure differential between the inlet and outlet manifolds
• Water or air pressure opens the Yardney 3-way valve causing the reverse flow of a portion of filtered water up through the stainless steel underdrain to hydraulically and uniformly lift the media bed
• The use of a hydraulically balanced underdrain in conjunction with a gravel pack creates a proper and uniform lift of the media bed while avoiding a turbulent backwash
• Particulate is released during the backwash event, exhausted through the backwash manifold and routed to a convenient location
• One tank at a time is backwashed while continuing to process water for use until the entire system is clean
• Once completed with the backwash, filtration continues until the next backwash event is called for

Superior backwash performance is achieved by the use of a hydraulically balanced under-drain and gravel which produces the proper lift and fluidization of the sand media bed to ensure complete release of entrapped particles which will produce a low pressure drop and longer run-times between backwashes.

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