30
5.5 Routine Standardization
. The sensor should be
standardized routinely if it is suspected that the
process might degrade or coat the sensor. When a
sensor cell constant is entered
CEL
is set to this value
and the cell factor
Fct
is set to 1.000. The first stan-
dardization recalculates the cell constant
CEL
.
Subsequent standardizations will change the cell fac-
tor
Fct
. Refer to Section 8.2.3 for a description of the
cell factor.
To perform a standardization do the following:
1.
Take a grab sample which is as close to the sen-
sor as possible. Write down the value the analyz-
er is reading at this time (C1).
2.
Measure the conductivity of the grab sample using
a calibrated bench analyzer referenced to
25°C/77°F or measured at 25°C. Write down this
value (C2).
3.
Before entering the reference value, note the
value the analyzer is reading now (C3) and com-
pare it to the value in Step 1. This accounts for the
change while the grab sample is being measured.
4.
Press the
PV
key once, then press
SELECT
.
Std
will display briefly followed by the Numeric display
with flashing digit.
5.
The corrected conductivity reference value may
be determined by multiplying the value in Step 2
(C
2
) by the value noted in Step 3 (C
3
) and divid-
ing the product by the analyzer value from Step 1
(C
1
):
C
2
x C
3
= C
RV
C
1
Enter this corrected reference value in the analyz-
er using the
SCROLL
(
é
) and
SHIFT
(
ç
) keys.
Then press
ENTER
.
6.
Note the cell factor value
Fct
. Press the
ACCESS
key twice quickly.
SCROLL
(
é
) to
Fct
press
SELECT
and note this value. Keep track of this
value to determine a sensor cleaning schedule.
5.6 Sensor Maintenance
. Before performing mainte-
nance or cleaning of the sensor, the Model 1054B
C should be placed in hold. This will place the
current output and relays in the states determined
in Section 4.6. Before removing the sensor from
the process, press the
HOLD
key twice. The
HOLD
flag will show to indicate the hold condi-
tion.
Always reenter the cell constant (Section 5.2) and
restandardize (Section 5.5) after cleaning or replace-
ment of the sensor.
Replace the sensor back into the process and press
the
HOLD
key twice again to remove the analyzer
from hold. The hold flag will disappear.
MODEL 1054B C
SECTION 5.0
START-UP AND CALIBRATION
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