FCA
‐
22
Instruction
Manual
Page 19
pH
Sensor
When
used
in
clean
water,
pH
sensors
require
little
maintenance.
pH
sensors
do
require
periodic
calibration
due
to
drift
in
the
reference
electrode
as
it
ages.
This
aging
causes
the
displayed
pH
value
to
be
higher
than
the
true
pH
of
the
sample.
Check
the
sensor
on
a
monthly
basis,
recalibrate
if
necessary.
Clean
or
replace
the
pH
sensor
when
it
becomes
noisy
and
slow
to
respond.
If
the
sensor
needs
cleaning
then
it
can
be
soaked
in
a
dilute
solution
of
HCl,
1
‐
5%,
for
10
‐
30
minutes.
This
will
remove
scale
or
biofilms
from
the
sensor,
rinse
well
and
soak
in
pH
4
buffer
for
15
minutes
before
returning
the
sensor
to
service.
Constant
Head
Flow
Controller
(CHFC)
The
CHFC
is
designed
to
provide
a
constant
flow
to
the
Free
Chlorine
Sensor
(FCS)
independent
of
variations
in
the
sample
pressure.
Decreasing
the
sample
flow
to
the
FCS
will
lower
the
output
of
the
FCS.
In
most
clean
water
applications
the
CHFC
requires
no
maintenance.
The
vertical
position
of
the
central
tube
sets
the
Head
Pressure
of
the
system.
It
is
set
for
optimal
flow
but
lower
flow
rates
can
be
attained
by
adjusting
its
height.
On
a
monthly
basis
visually
inspect
the
CHFC,
the
interconnecting
tubing
and
the
drain
tubing
for
obstructions
or
sediments
that
may
reduce
the
flow.
The
CHFC
and
tubing
can
be
easily
disassembled
and
cleaned
with
soap
and
water.
Some
dirty
applications
like
Cooling
Towers
may
require
periodic
cleaning
due
to
sediments.
