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Backwash Inlet Valve V3 - This connection is located at the bottom of the vessel. This connection is USUALLY
connected to the clean backwash water supply. Backwash water can either come from a mains water supply or
from a pumped external water supply. In some cases the backwash water can be supplied via the inlet process
feed pump, however this requires a special pipe-work configuration.
Backwash Outlet Valve V4 - This is the outlet connection for the dirty backwash water. This connection is
connected to either a collection tank or to a suitable foul water drain. It is important that this pipe is unobscured
and only has a flow control valve. We recommend that you install a flow control valve (full bore manual gate valve)
at this location to control the backflow rate. The valve can be supplied at extra cost, if required.
Note : V2 and V3 can be reversed to match the plant requirements. If this is required, please consult Amiad Water
Systems as sometimes the PLC program needs to be amended.
Filter Operation
When the control system is powered up, the inlet and outlet valves (V1 and V2) are open and the backwash drain
and backwash inlet (V4 and V3) are closed. The process water is delivered into V1 via the system pressure. The
water feed is directed through the
Dual Vortex Generator.
The water is filtered by the media and exits the system
via V2 and on to the process system; The outlet gate valve (if used) controls the filter throughout.
The filter continues on-line filtration until backwash is initiated. This is usually done via a pressure differential
switch (supplied as part of the control package), a timer (adjustable through the controller), or manually, by
pressing the backwash button.
Once backwash is triggered by either of the above,
V1 and V2 close –
the filter will no longer be producing any
process water until the backwash cycle is complete.
The media bed is allowed to settle (this is called the “ dwell time ”) for about 1-1.5 minutes. This is to allow the
media suspended above the bed to settle before commencing the backwash cycle.
After the media has settled the backwash sequence begins.
V4 opens, shortly followed by V3 - this allows backwash water to be applied into the filter; this water is
distributed equally across the bed area and has the effect of fluidizing the glass media. The backwash water lifts
the lighter contamination from the media strata and flushes contamination from the system via the backwash
drain connection V4. This can be fed to a suitable foul drain or collected for further processing and water recovery.
The backwash gate valve (if used) will be adjusted on commissioning to ensure the bed is not over fluidised during
backwash, as in this event media could be sent to drain, reducing filtration efficiency and requiring more frequent
media top ups. After the backwash is complete, usually between 2-4 minutes (this is adjusted on commissioning to
suit the application and can be confirmed by visually checking that the backwash water is running clear), V3 and
V4 Close.
After a dwell time of 30 seconds
V1 and V2 open
to process filtration again. This cycle is repeated as
required depending on loading.