BT61i pH Sensor User’s Guide
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3
Calibration
The CMA pH sensor is supplied calibrated. The output of the sensor is linear with
respect to pH value. The supplied calibration function is:
pH = -‐4.04 * V
out
(V)+ 13.68
The Coach program allows selecting the calibration supplied by the sensor memory
(EEPROM) or the calibration stored in the Coach Sensor Library. For better accuracy a
new user calibration can be performed in the Coach program. In order to calibrate a
pH Sensor, you should have a supply of pH buffer solutions that cover the range of pH
values you will be measuring. To perform a two-‐point calibration:
•
Rinse the tip of the electrode in distilled water.
•
Place the electrode into one of the buffer solutions. When the voltage reading
stabilizes, enter the pH value.
•
For the next calibration point, rinse the electrode and place it into a second buffer
solution.
•
When the voltage reading stabilizes, enter the second pH value.
•
Test your calibration in different known pH buffer solutions.
Suggested experiments
The pH sensor can be used for various experiments in
biology, chemistry and environmental science such as:
•
Measuring pH values of different acids and bases,
•
Acid-‐base titration experiments,
•
Monitoring pH during chemical reactions,
•
Investigating of water quality in streams and lakes.
Practical information
•
Do not place the electrode in base solution (pH > 10) for longer than few hours.
This can affect the glass of the electrode.
•
The pH electrode has a limited operational life and can be ordered separately.
During a measurement the end of the plastic tube of the electrode has to be held
approximately 1 cm in the liquid.
