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Appendix E: General Information for Calibrating with LD2 Control Box
The Little Dipper
™ 2 may be purchased as a sensor integrated with control boxes from third
party vendors, in which case the calibration instructions in section 3.2 cannot be used to
calibrate or set a new range for control box wired sensors
. Refer to the control box’s manual for
calibration instructions.
Every control box will have its own specific procedure for calibrating integrated sensors. The
following is a general procedure for calibrating your control box integrated sensor:
1) Make sure the control box is powered on and power is getting to the sensor.
2) Put your hand in front of the sensor and look at the response displayed on the control
box display; the response should increase
as your hand gets closer to the sensor’s
optical head and vice versa.
3)
Enter the control box’s calibration mode.
4) Put the sensor in blank solution or source water that does not contain the fluorophore of
interest.
5) Using control box commands set the blank.
6) Put the sensor in a solution with a known concentration of the fluorophore of interest.
7) Using control box commands input the concentration value of the standard solution
being measured.
8) Using control box commands set the standard solutions response.
9) Make sure the settings for this sensor calibration are saved.
Now you can read both blank and standard solution and the control box should display actual
concentration values for those solutions read.
It is recommended that a final check be made after the unit is calibrated. To make this check
you will need to dilute your standard solution by half using your blank solution or source water.
Simply fill a container half full with your standard solution and add approximately the equivalent
volume of blank solution or source water to your standard solution. Stir the solution and read it
using your calibrated sensor. The control box should display approximately half of the
calibration value set during the calibration procedure.
