• Be aware of the temperature of the buff ers being used. Generally buff er manufactures write on their
label at what temperature the pH is its true value (generally 77°F, 25°C). Temperature can infl uence
dissociation and thus if your calibration is done with a buff er not at its prescribed temperature, your
calibration will be inaccurate. It is best to calibrate with buff ers that have an accurate pH close to your
operating conditions.
• Air bubbles and other liquids can form around the outside of the sensor and aff ect the accuracy of the
reading. Be sure to remove any air bubbles upon installation.
4 – 7 pH, 7 – 10 pH & 4 – 10 pH:
These are two point calibrations carried out with two known pH buff er
solutions.
1. In the Temperature calibration screen, set the Temperature mode to manual and enter the actual
buff er solution temperature.
NOTE: pH bu
ff
er calibrations are somewhat temperature dependent. pH bu
ff
ers are usually accurate
at 25ºC. Error in pH readings can occur if bu
ff
er temperatures are drastically di
ff
erent from their
prescribed temperature (+/- 5ºC). If the temperature di
ff
erence is greater than this margin, consider
adjusting bu
ff
er temperature or performing a sample calibration.
2. Once the calibration method is selected, the fi rst buff er solution required will be displayed on the
screen. Place the pH electrode into the appropriate buff er and select ‘Begin’.
3. The software waits for the reading to stabilize for 25 seconds before accepting or rejecting it as a
valid calibration point. The countdown timer will appear on the screen in real-time. Note: The pH
value will not be displayed.
4. If the calibration point is accepted, an “accepted” screen will appear. Press down to clear the screen
and the next buff er solution required will appear.
5. Place the pH electrode in the appropriate buff er solution and select ‘Begin’.
6. The software will wait for a stable reading over 25 seconds. If the second calibration point is
accepted, an “accepted” screen will appear. Press down to clear and the pH calibration is complete.
7. Place the pH electrode back into the sample solution and change the Temperature back to the original
operating conditions.
Sample
Calibration:
This calibration is carried out with the pH electrode left installed in its holding cell
with the sample water fl owing through it. However, be sure that the Temperature displayed on your unit
is accurate before calibrating the pH.
1. If this calibration option has been selected, the following screen will require the operator to enter the
pH of the sample water in which the calibration will be done.
2. Use a hand held pH meter to measure the pH of the sample water and then enter the pH of the
sample on the screen.
3. Before proceeding check that no air bubbles have formed on the tip of the pH electrode. Select
‘Begin’; the software will wait for a stable reading over 25 seconds before accepting or rejecting the
calibration point. If the calibration point is accepted, press the down key and the pH calibration is
complete.
NOTE: If at any point your pH calibration is rejected, the entire calibration procedure will need to be
repeated. If the problem persists, see the troubleshooting section below.
AOut:
This branch accesses the settings for the four 4-20mA output channels. (AO1, AO2, AO3, AO4)
Select AOX:
Each of the four analog output channels can be independently set to represent one of the
following parameters.
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