Chemical Doser Design
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h1. Chemical Doser Design {float:right|border=2px solid black|width=260px} [!Laboratory Research Set-ups^Labeled Robust ACD freestanding F08 2.JPG|width=260px!|Laboratory Research Set-ups] {float} |
The
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chemical
...
doser
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(CD)
...
has
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three
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principle
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components:
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a
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float,
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a
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lever
...
arm,
...
and
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a
...
...
...
(FC).
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The
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float
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currently
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used
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in
...
the
...
lab
...
for
...
data
...
collection
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is
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a
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45.5
...
cm
...
long
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4
...
in
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PVC
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tube
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capped
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at
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both
...
ends
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and
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partially
...
filled
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with
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sand
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so
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that
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it
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weighs
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8
...
lbs.
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It
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rests
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33.5
...
cm
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below
...
and
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12
...
cm
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above
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the
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water
...
line
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in
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a
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virtual
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grit
...
chamber,
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which
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is
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a
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deep
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bucket
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with
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a
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pressure
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sensor
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at
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its
...
base.
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This
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pressure
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sensor
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provides
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readings
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of
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the
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water
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level
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in
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the
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bucket.
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The
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float
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is
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connected
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via
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low-elasticity
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fishing
...
line
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to
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the
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lever
...
arm.
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The
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lever
...
arm
...
is
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a
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68
...
cm
...
length
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of
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1
...
1/4
...
in
...
schedule
...
40
...
PVC
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pipe
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with
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a
...
pivot
...
point
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at
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34
...
cm
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(the
...
center).
...
Opposite
...
of
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the
...
pivot
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there
...
are
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notches
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cut
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into
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the
...
pipe
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at
...
5
...
cm
...
length
...
intervals.
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The
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chemical
...
doser
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hangs
...
from
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these
...
notches.
...
A
...
1
...
1/2
...
in
...
schedule
...
40
...
PVC
...
pipe
...
attached
...
to
...
a
...
flange
...
base
...
holds
...
up
...
the
...
lever
...
arm.
...
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[!Laboratory Research Set-ups^IMG_7246.JPG|width=260px!|Laboratory Research Set-ups]
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The
...
top
...
of
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the
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pipe
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is
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cut
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in
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a
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saddle
...
shape
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to
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fit
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the
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lever
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arm
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through
...
it
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and
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create
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the
...
pivot.
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The
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height
...
of
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this
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base
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pipe
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depends
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on
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the
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design
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constraints
...
of
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the
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plant
...
it
...
will
...
be
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built
...
for.
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The
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FC
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should
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be
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attached
...
to
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the
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base
...
pipe
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with
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two
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clamps
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that
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are
...
interconnected
...
so
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that
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they
...
firmly
...
anchor
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the
...
FC
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at
...
the
...
appropriate
...
height
...
for
...
...
...
...
.
...
Only
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one
...
clamp
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was
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used
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during
...
experimental
...
testing
...
because
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the
...
FC
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was
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being
...
continually
...
checked
...
and
...
re-zeroed,
...
and
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it
...
was
...
being
...
used
...
in
...
a
...
very
...
controlled
...
environment.
...
Additional
...
clamps
...
would
...
be
...
necessary
...
for
...
robust
...
plant
...
operation.
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\\ {float:right|border=2px solid black|width=260px} [!Laboratory Research Set-ups^IMG_7243.JPG|width=260px!|Laboratory Research Set-ups] {float} |
The
...
chemical
...
dosing
...
tube
...
is
...
a
...
tube
...
with
...
an
...
open
...
T
...
connection
...
at
...
the
...
top,
...
which
...
allows
...
the
...
FC
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outflow
...
tubing
...
to
...
drain
...
through
...
a
...
pressure
...
break
...
T.
...
The
...
tubing
...
exiting
...
the
...
pressure
...
break
...
T
...
has
...
a
...
larger
...
diameter
...
than
...
the
...
tubing
...
entering
...
it.
...
The
...
pressure
...
break
...
and
...
larger
...
outflow
...
tubing
...
allow
...
a
...
free
...
surface
...
at
...
the
...
same
...
height
...
as
...
the
...
discharge
...
to
...
the
...
rapid
...
mix
...
(minus
...
head
...
loss)
...
to
...
form
...
inside
...
the
...
larger
...
tube
...
while
...
air
...
can
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also
...
flow
...
through
...
the
...
tube.
...
Currently
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¼
...
inch
...
outer
...
diameter
...
tubing
...
is
...
used
...
to
...
connect
...
the
...
flow
...
controller
...
to
...
the
...
pressure
...
break
...
T,
...
but
...
it
...
is
...
not
...
known
...
what
...
size
...
tubing
...
is
...
necessary
...
to
...
allow
...
air
...
to
...
flow
...
after
...
the
...
T.
...
Experience
...
has
...
indicated
...
that
...
½
...
inch
...
outer
...
diameter
...
tubing
...
is
...
large
...
enough,
...
but
...
it
...
is
...
possible
...
that
...
tubing
...
with
...
an
...
outer
...
diameter
...
as
...
small
...
as
...
3/8
...
inch
...
could
...
work
...
as
...
well. The larger tube is then connected to 1/4 in outer diameter tubing, which connects the CD to the rapid mix. It is unclear if this final connection is needed, though, and it may be removed so that the larger tubing connects the T to the rapid mix directly.
For laboratory testing, water flows from the bottom of the chemical dosing tube to a plastic column with a pressure sensor at the bottom. This pressure sensor gives readings of water height in the column, which can be converted into flow rates from the FC.