Hach-Lange 1720E Low Range Turbidimeter - Manual (Page 31)

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Maintenance
4. Replace the bubble trap cover and head assembly on the top of the body.
5. Restore sample flow to the instrument.
6. Calibrate the instrument using one of the methods in section 5.5 on page 18 .
If the above cleaning procedures have been performed and the turbidimeter readings are
still noisy, the bottom plate and gasket may need to be removed and cleaned. Carefully
perform the following procedure to ensure the turbidimeter body integrity is maintained.
1. Turn off sample flow to the turbidimeter body.
2. Remove the head assembly, bubble trap cover, and bubble trap (by lifting it vertically)
from the body.
3. Drain the body by removing the plug from the bottom of the body.
4. Lift the body off of its mounting screws.
5. With the body turned upside-down, remove the two Phillips-head screws holding the
bottom plate.
6. Lift the bottom plate off the body; set the gasket aside for use in reassembly.
7. Use a soft brush and a dilute cleaning solution (as prepared above) to clean the
bottom plate and inside surfaces of the turbidimeter body. Rinse the entire body and
bottom plate with ultra-filtered deionized water.
8. Reassemble by inserting the gasket into the molded channel in the bottom plate.
9. Fit the bottom plate onto the turbidimeter body.
10. Reinstall both screws and carefully tighten to 15 inch-lb maximum.
11. Reinstall the turbidimeter onto the wall mounting screws.
12. Replace the bubble trap, bubble trap cover, and head assembly on the top of the body.
13. Restore sample flow to the instrument.
6.4.3 Replacing the Lamp Assembly
The Lamp Assembly is located on the head assembly. Under normal use, Hach
recommends replacing the lamp once a year to maintain peak performance. Replacement
bulbs have been “burned-in” at the factory and are ready for installation and use.
To change the lamp, refer to Figure 7 on page 28 and perform the following steps:
1. Disconnect power to the controller to remove all power to the turbidimeter.
2. Disconnect the lamp leads by unplugging the connector.