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1.
Two Large mouth beakers
2.
Sodium sulphite Na
3.
Aquarium air pump
4.
Magnetic stirrer
Preparing solutions
Reference Point 1 solution – Oxygen saturated solution at expected temperature and salinity of deployment
environment
1.
Fill the large beaker with 2 L of water. And install magnetic stirrer.
2.
Bubble air through the water using an air pump (an aquarium air pump would work).
3.
Switch ON the air-pump and the magnetic stirrer.
Reference Point 2 solution – Dissolved oxygen concentration of zero
1.
In a beaker, dissolve approximately 5 tsp of sodium sulfite (Na2SO3) into 500 mL tap water.
2.
Mix the solution thoroughly with a magnetic mixer. The solution will be oxygen-free after 15 minutes.
Steps
1.
In Ruskin, configure the instrument to sample at a fast rate, between 6 Hz and 3 seconds.
2.
Use Sync to PC to ensure the logger clock is synchronized to the PC clock, and ensure the end time is
set so that the logger will keep sampling until calibration is complete.
3.
Submerge the dissolved oxygen sensor in the Reference Point 1 solution for at least 15 minutes near
the stirrer so that it is in the best mixed area of the bath.
4.
Take sample readings for at least 15 minutes for the 100% calibration point, making note of the time
that the sample is being measured.
5.
Submerge the dissolved oxygen sensor in the Reference Point 2 solution for at least 15 minutes for the
0% calibration point, making note of the time that the sample is being measured.
6.
Retrieve the data from the data logger as per the steps in Download.
7.
The calibration data should now be displayed in the Plot view. In the Properties view, go to Analysis
tab > Calibration tab.
8.
Select the dissolved oxygen sensor type from the drop down list.
9.
The Number of Samples spinner box is automatically set to 100.
This value is the number of sample points Ruskin will average the calibration coefficients for the
sensor. Typically, this value should be in the range of 50 to 100 samples.
10.
Click on a stable point in the Plot view corresponding to 100% oxygen. In the table in the first row,
under Real Avg, enter 100 and press enter.
11.
Select the check box in the second row in the table, then click on a stable point in the Plot view
corresponding to 0% oxygen. In the table in the second row, under Real Avg, enter 0 and press enter.
12.
Ruskin automatically calculates the calibration coefficients, and these values appear in Calculated
coefficients. Clicking the Copy button saves the new calibration coefficients to the clipboard.
13.
Follow the steps in
logger.
RBR#0006106revG
SO
2
3
Change calibration coefficients
to update the coefficients for this sensor in the data
– 50
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