ATI
Q45S/87 Portable Wet H
2
S Monitoring System
Part 6
– Calibration
33
O&M Manual
– Rev-C
5. Press the ENTER key. The screen will display a flashing
1-Ref
for span
calibration or a
2-Zer
for zero calibration. Using the UP arrow key, set for a
1-
Ref
span calibration and press ENTER.
6. The system now begins acquiring data for the calibration value. As data is
gathered, the units for ppm may flash. Flashing units indicate that this
parameter is unstable. The calibration data point acquisition will stop only
when the data remains stable for a pre-determined amount of time. This can
be overridden by pressing ENTER. If the data remains unstable for 10
minutes, the calibration will fail and the message
CalUnstable
will be
displayed.
7. The screen will display the last measured ppm value and a message will be
displayed prompting the user for the span gas value. The user must then
modify the screen value with the arrow keys and press ENTER. The system
then performs the proper checks.
8. If accepted, the screen will display the message
PASS
with the new sensor
slope reading, then it will return to the main measurement display. If the
calibration fails, a message indicating the cause of the failure will be
displayed and the FAIL icon will be turned on. The range of acceptable
values for sensor slope is 25% to 300%.
The sensor offset value in % from the last span calibration is displayed on the
lower line of the Default Menus for information purposes.
6.4
Temperature Calibration
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
feature prior to calibration to lock out any output fluctuations.