Long-term chamber maintenance

Both the 8200-104 and 8200-104C Long-Term Chambers are designed to require minimal maintenance. Most of the components are modular and are intended to be easily replaced if needed.

Note: Before doing any maintenance or repairs to a long-term chamber first disconnect the PWR/COM cable from the chamber.

Replacing the collar gasket

Around the opening of the chamber base is a black neoprene collar gasket that seals around a soil collar. This gasket should not need to be replaced unless it has become cracked, brittle, or otherwise damaged. Two spare collar gaskets (part number 6581-060) are included in the replacement gasket kit (part number 8100-612) and additional gaskets can be ordered from LI-COR.

Before you disconnect the PWR/COM cable from the chamber, you will first need to move the chamber to its open position. If the open position does not allow you to fully access the gasket, you will need to change the open position. See Changing the open position.

To replace the gasket, remove the 24 screws around the gasket plate and remove the plate and gasket. Be careful not to lose the screws, but if you do there are spares in the chamber gasket kit. Align the new gasket with the screw holes on the plate and screw the plate to the chamber base. Tighten each screw to 0.45 Newton meters.

Replacing the chamber bowl gasket

The bottom of the bowl has a gasket that forms a seal when the chamber is closed. The gasket should be replaced if it has visible damage or if you determine that it leaks when the chamber is closed. A spare gasket (part number 224-07606) is included in the chamber spares kit, which comes with each chamber.

1. Open the chamber.

   If the chamber is closed and the system is powered on, you can do this in the software under Tools, Manual System Control, or you can press the OPEN/CLOSE button on the side of the chamber.

2. Remove the damaged gasket from the bowl.

   You can pull the gasket off or use a razor blade to trim it. Be careful not to damage the finish of the chamber bowl. After removal, clean the chamber surface with alcohol to remove any adhesive residue.

3. Cut a piece of new gasket material to a length of about 84 cm (33").

4. Remove the adhesive backing from the new gasket material and install the gasket around the bottom of the chamber bowl.

5. Trim the ends of the new gasket so both ends are touching and apply Loctite (208-08149; included in the gasket kit) to glue the ends together.

6. Adjust the chamber arm.

7. Park the chamber by pressing the OPEN/CLOSE button on the side of the chamber twice.

   The bowl will center over the collar gasket, but not fully close.

8. Use a 3/8” wrench to loosen the arm mounting nuts.

   

9. Adjust the position of the arm assembly so that the bowl is centered over the gasket.

   When centered, tighten the mounting nuts.

Replacing the thermistor (8200-04 Opaque Long-Term Chambers)

The thermistor in the long-term chamber may need to be replaced if it becomes damaged or stops working. A new thermistor for the Opaque Long-Term Chamber is part number 9982-033.

1. Disconnect the thermistor connector from the connector on the chamber.

2. Remove the two cable clamps with a Phillips screwdriver.

   

3. Cut the four cable ties on the chamber arm.

   

4. Cut the two cable ties holding the thermistor cable to the two air tubes, one on each end.

5. Remove the old thermistor cable from the large braided wrap, freeing it from the two air tubes.

   

6. Place a 5/8” wrench on the black nut on top of the bowl and use a socket or adjustable wrench to remove the black plastic nut on the inside of the bowl.

   

7. Install the new thermistor, using the same tools (torque to 1.1 Nm (10 in-lbs)).

8. Re-wrap the thermistor cable in the braided wrap, and secure the ends with two small cable ties (part number 218-08499).

9. Loosely install four small cable ties (part number 218-08499) to secure the braided cable to the support arm.

   

10. Align the portion of the tubing and cable assembly that divides into three separate cables with the edge of the base plate.

11. Reinstall the two cable clamps on the side of the enclosure, making sure to reattach the connector caps as well.

12. Reconnect the thermistor Turck connector to one of the Sensor connectors on the front of the enclosure.

13. Fully tighten the cable ties, and trim the excess ends from them.

Replacing the chamber shaft seal

The shaft seal assembly on 8250-104/C Long-Term Chambers should be replaced if it fails. Failure is indicated by the mechanism squealing or shuddering during motion.

Components

The chamber shaft seal replacement kit (part number 8200-928) includes the following components.

Description	Part Number
Shaft Seal Assembly	9982-025
Thread Lock 222 Purple (0.5 mL)	208-10201
Synthetic Oil (2 mL)	210-11015
Rheolube 368A (1 mL)	210-11016

1. With the chamber powered on, press the OPEN/CLOSE button twice in succession to move the chamber to its “Park” position.
2. Disconnect the chamber power/data cable.

3. Use a 3/8" wrench to remove the arm mounting nuts on the underside of the arm.

   Collect the nuts, lock washers, and flat washers. Leave the cable and tubes connected and set the bowl assembly aside.

   

4. Use a 9/64" hex key to remove the two hex bolts on the chamber adapter.

   

5. Use a Phillips #1 screwdriver to remove the four screws and washers from the shaft seal assembly.

   

6. Remove the shaft seal assembly from the drive shaft.

   If it is stuck, grasp it firmly and twist it loose. Remove the O-ring if it sticks to the housing.

   

7. Clean any residue off of the top of the housing.

   Use a mild detergent, if needed. Do not use sharp objects, and do not damage the finished surface. Make sure the sealing surfaces are clean and smooth before installing the new shaft seal assembly.

8. Lubricate the new shaft seal assembly with oil and grease from the shaft seal assembly kit.
   • Apply the full quantity of synthetic oil to the felt washer inside the shaft seal assembly.
   • Apply a generous layer of Rheolube to the O‑ring and rubber seal with your finger or a cotton-tipped swab.

   

9. Be sure the O-ring is in place on the bottom of the shaft seal assembly.

10. Install the new shaft seal assembly on the shaft.

    You may need to press firmly and twist the assembly to get the O-ring over the shaft, but use caution and be sure not to cut, pinch, or gouge the O-ring or seal.

11. Apply a droplet of Loctite® from the spares kit to each of the four screws, then install the screws and washers to secure the assembly.

    Tighten the screws.

12. Wipe any oil or grease off of the top of the shaft and then install the chamber adapter.

    The slotted side goes toward the chamber opening. Tighten the hex screws.

13. Install the bowl and arm assembly using the nuts and washers.

    1. Tighten the nuts only finger tight, and then adjust the chamber bowl so that it is centered over the soil collar gasket.

    2. Tighten the two arm mounting.

You have completed the chamber shaft seal replacement. You can verify that the chamber operates correctly by connecting it to the power supply and opening and closing the chamber.