ATI
PQ45P pH System
Part 7
– DataLogger
29
O&M Manual
Rev-B (7/15)
5.
The display will prompt the user to place the sensor in the first buffer and press ENTER. If the
sensor has been placed into this buffer already, once the temperature has stabilized, press
ENTER to continue.
6.
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 first buffer
value from the two values entered into the Set Buffers selection.
7.
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. After adjusting this value, or to accept the automatic value, press ENTER.
8.
The system now begins acquiring data for the calibration value of this buffer point. As data is
gathered, the units for pH and temperature may begin to flash. Flashing units indicates that this
parameter is unstable. The 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
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.
