Hach-Lange pHD sc - Manual (Page 28)

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Maintenance
6. Remove the sensor from the soap solution, and rinse the sensor again in clean, warm
water.
7. After cleaning, always calibrate the measurement system.
5.2.1 Replacing the Standard Cell Solution and Salt Bridge
If calibration cannot be attained, rejuvenate the sensor by replacing its standard cell
solution and salt bridge as shown in
Figure 12 . If calibration is still not possible, refer to
Section 6 on page 23 .
1. To remove the salt bridge, hold the sensor upright (electrode at top), and use pliers or
a similar tool to turn it counterclockwise. Take care not to damage the protruding
process electrode. Properly discard the old salt bridge.
2. Replace the standard cell solution in the sensor reservoir.
a. Pour out the aged solution, and thoroughly flush the reservoir with distilled water.
b. Fill the reservoir to the bottom of the salt bridge threads with fresh standard cell
solution (Cat. No. 25M1A1025-115).
3. Install a new o-ring then carefully thread the new salt bridge clockwise until it is
finger-tight and the bottom surface of the salt bridge is in full contact with the top
surface of the sensor body. Do not over tighten.
Figure 12 Replacing Standard Cell Solution and Salt Bridge
1. Salt Bridge 2. Sensor
1 2