Backflushing
Backflushing is a process used to clean filters by reversing the flow of fluid through the system. Effective, economical backflushing can be difficult to achieve since no two filtration operations are alike. The amount and type of contaminant, system pressures, pumps, filter housing, can all vary. System design and backflush principles are predominantly the same, but operational parameters must be tailored to the application by field trials(at a pilot plant, side stream or full operation).
Backflushing could be a powerful tool in many filtration applications, potentially extending system life and reducing cost. Unfortunately, most filtration systems are not set up for backflushing. Filter cartridges with a narrow pore size distribution and good surface, rather than depth, retention (such as sintered porous plastic, stainless steel or ceramic) are the best candidates for a successful backflushing operation.
 Since most currently available filters are not effectively backflushed, many operators are unfamiliar with how to implement backflushing; and therefore, unaware of the potential advantages of this technique.
Existing filter hardware can be used for backflushing in most applications. Though not always the most effective method, existing filter hardware can prove economical either as a permanent solution or for trial to show the economics of a more effective process.
Recommended Backflush Parameters:
Pressure Differential for Backflush Initiation – 5 to 10 psid
(over clean pressure differential)
Air Reservoir Pressure – No more than 50 psi
Backflush Rate – 1.5 to 2.0 times forward flow rate
Backflush Valve Open Rate (Trial and Error) – The faster the better without damaging or dislodging cartridges
Backflush Time – Sufficient to remove all upstream fluid volume
Maximum Clean Water Pressure Differential – After backwashing the differential pressure exceeds, the starting differential plus 50% or when time between cycles is too short.
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