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ATI
Q45P pH System
Part 5
–Calibration
36
O&M Manual
Rev-B (7/15)
5.4
Temperature Calibration
The temperature input is factory calibrated for the highest accuracy.
Temperature calibration is not recommended; however, it is provided for
applications in which very long cable lengths are needed. For example, at 50
feet, readings may be off ±0.2 °C.
The temperature calibration sequence is essentially a 1-point offset calibration
that allows adjustments of approximately ±5 °C.
The sensor temperature may be calibrated on line, or the sensor can be removed
from the process and placed into a known solution temperature reference. In any
case, it is critical that the sensor be allowed to reach temperature equilibrium with
the solution in order to provide the highest accuracy. When moving the sensor
between widely different temperature conditions, it may be necessary to allow the
sensor to stabilize as much as one hour before the calibration sequence is
initiated. If the sensor is on-line, the user may want to set the output HOLD (see
section 4.11) feature prior to calibration to lock out any output fluctuations.
Procedure
1. Scroll to the CAL menu section using the MENU key and press ENTER or the
UP arrow key.
2. Press the UP arrow key until
Cal Temp
is displayed.
3. Press the ENTER key. The message
Place sensor in solution then press
ENTER
will be displayed. Move the sensor into the calibration reference (if it
hasn’t been moved already) and wait for temperature equilibrium to be
achieved. Press ENTER to begin the calibration sequence.
4. The message
Adjust temp value then press ENTER
will be displayed, and
the right-most digit will begin to flash, indicating that the value can be
modified. Using the UP and LEFT arrow keys, modify the value to the known
ref solution temperature. Adjustments up to ± 5 °C from the factory calibrated
temperature are allowed. Press ENTER.
5. The calibration data gathering process will begin. The message
Wait
will
flash as data is accumulated and analyzed. The
°C
or
°F
symbol may flash
periodically if the reading is too unstable.
6. Once completed, the display will indicate
PASS
or
FAIL
. If the unit fails, the
temperature adjustment may be out of range, the sensor may not have
achieved complete temperature equilibrium, or there may be a problem with
the temperature element. In the event of calibration failure, it is
recommended to attempt the calibration again immediately.