ATI
Q45P pH System
Part 5
–Calibration
34
O&M Manual
Rev-B (7/15)
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
Cal
Unstable
will be displayed.
9.
Once the first calibration value has been established, the screen will prompt the
user to move the sensor to the second buffer. At this point, rinse sensor with
water and move the sensor into the second buffer solution. Allow temperature to
stabilize, and then press ENTER.
10.
The present pH value will be displayed and the secondary line of the display will
flash
Wait
for approximately 10-15 seconds. At this time the system is
attempting to recognize the second buffer value from the two values entered into
the Set Buffers selection.
11.
The screen will display the buffer value to be used for calibration. If the user
chooses to change this value, the arrow keys can be used to modify the value.
Any value between 0.00 and 14.00 pH can be entered. The second buffer must
be at least 2 pH units away from the first. After adjusting this value, or to accept
the automatic value, press ENTER.
12.
The system now begins acquiring data for the calibration value of this buffer
point. As data is gathered, the units for pH and/or temperature may again flash,
indicating unstable parameters.
13.
If accepted, the screen will display the message
PASS
with the new slope and
offset readings, 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 sensor offset value in % from the last span calibration is displayed on the
lower line of the Default Menus for information purposes.
5.3
Performing a 1-Point Calibration
The 1-point, or sample calibration method does not utilize the automatic buffer
recognition and compensation system. This calibration method is intended to be
primarily used as an on-line calibration method, in which the actual calibration
point will not be a buffer value. However, the sensor can be removed and
calibrated in a separate buffer. During calibration, the system will display the
current pH reading and the user can manually enter a reference value from a lab
grab-sample or a comparative reference instrument.
Procedure
1. Determine whether the calibration will be done on-line or with the sensor
removed and placed into a buffer. If the sensor is removed from the
application, rinse and clean if necessary.
