Hach-Lange 5740 sc - Manual (Page 19)

15
Operation
4.7.2 Sample Cal—Calibration by Comparison to a Winkler Titration
1. Select the Main Menu.
2. From the Main Menu, select SENSOR SETUP and confirm.
3. Select the appropriate sensor if more than one is attached and confirm.
4. Select CALIBRATE and confirm.
5. Select SAMPLE CAL an confirm.
6. Select the available Output Mode (Active, Hold, or Transfer) and confirm.
Note: An output that has been placed in Hold or Transfer status will be automatically released when
the calibration is complete.
7. Remove the sensor from the process stream and gently wipe with a wet cloth to
remove all debris and biological growth. Remaining debris will affect the Winkler
Method of analysis.
8. Measure 1000 mL of deionized water. Allow the water to come to the thermal and
dissolved oxygen equilibrium (approximately 20 minutes).
9. Fill a standard BOD bottle and then place the sensor in a beaker containing the
remainder of the deionized water.
10. Perform the Winkler Tritration using Cat. No. 1469-00 Winkler Test Kit on the deionized
water in the BOD bottle while waiting for the process sensor to stabilize.
11. Move the sensor to the sample.
12. The display will show “PRESS ENTER WHEN STABILIZED” and the current DO and
temperature readings. After confirmation or when the reading has been accepted as
stable, the display will change to an entry screen. Without confirmation, the sensor will
determine when the reading is stable. Two to three minutes for the reading to stabilize
is typical, however, if it has not stabilized after 45 minutes, the display will show
“UNABLE TO CALIBRATE”.
13. When a stable reading has been accepted, the display will show “SAMPLE CAL” and
an area for entry of the value obtained from the comparison method. When the entry
screen is displayed, enter the value from the hand-held or winkler titration and confirm.
14. After calibration, one of the responses in Table 2 on page 17 will be displayed.