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Filter
Operation
Liquid
enters the filter through the inlet header and then to each
of the pods via their 4" inlets. The inlet to each
pod has been specially designed to give a tangential angle
of entry for the incoming liquid. This angle then causes
the dirty fluid to take on a centrifugal action inside each
pod. The purpose of this centrifugal action is to hold the
larger particles in suspension while the filter elements
remove the smaller and lighter particles. Further, the velocity
of liquid as it enters into the pod is drastically reduced
by the great change in diameter. This encourages larger
debris to settle to the bottom of the pod, above the backwash
valve. In this way, the filter is able to accommodate larger
quantities of debris without overloading the surface area
of the filter elements. All debris is kept to the outside
of the filter elements while the clean liquid is discharged
from each pod by their 4" outlets. The clean discharge
from each pod flows away from the filter via the discharge
header.
At a
predetermined differential pressure, the filter will automatically
carry out a 100% self-cleaning operation called a backwash. This
backwash operation is designed to clean all the pods in
sequence while still maintaining the designed flow of clean
liquid to the system. The sequence is as follows:
Each
pod is cleaned in turn by simultaneously closing the 4"
inlet valve and opening the 2" backwash valve fitted
at the bottom of the pod. This backwash valve is fitted
immediately below the pod to enable the debris to be removed
as quickly as possible, in addition larger debris will be
deposited on
top of this valve. By opening this valve, the backwash outlet
from the pod is now open to atmospheric pressure, which
will cause a portion of clean filtered liquid to flow through
each of the seven elements in a reverse direction. This
reverse supply of liquid, will cause the filter element
to open along its entire length, vibrating at the same time,
thereby achieving a very thorough cleaning effect.
In this
way, all debris is removed from the outside of the filter
element, even debris that may be lodged on the surface of
the filter element. This results in an efficient backwash
with very little fluid loss. The backwash sequence to clean
each pod is normally 2 - 4 seconds. When one pod has been
backwashed, the next pod is then cleaned and so on until
all the pods have been backwashed. Once the backwash has
been completed, the filter will return to its clean differential
pressure every time.
More Information on
System
2000
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