Replace the O-rings

Refer to Open and close a compact instrument for details on accessing the O-rings.

The O-ring removal tool and silicone compound are available in the support kit.

Care for the O-rings is the single most important item of maintenance on any submersible RBR instrument. A water leak can damage the circuit board beyond repair and cause complete data loss. Every instrument seal depends upon the O-ring; therefore, proper O-ring maintenance is crucial.

The O-rings may lose elasticity over time, even when the instrument is not deployed. RBR strongly recommends replacing the O-rings regularly.

RBR compact instruments use two O-rings (see Fig. 15). One is the main O-ring, and the other is the backup. Both are required to protect the instrument from flooding.

To access the O-rings, open the instrument.
0-rings SL3 (1).png
Fig. 15.    Location of the O-rings. (a) main O-ring. (b) backup O-ring.

Inspecting the O-rings and mating surfaces
Visually inspect the O-rings and their mating surfaces, checking that each of the following is smooth and free of nicks or damage:

  • The surface of the O-ring itself

  • The mating surface on the inside of the case, between the threads and the open end

  • The groove in the end-cap where the O-ring sits

When handling the O-rings:

  • Avoid using any object that could scratch the O-ring or any of its mating surfaces.

  • If dirt is present in the O-ring groove, remove the O-ring as described below and thoroughly clean the groove.

  • Do not return an old O-ring to the instrument. If you remove the O-ring from the instrument for any reason, always replace it with a new one.

  • If the surfaces of the O-ring groove are scratched, pitted, or damaged, contact RBR for advice.

Replacing the O-rings

Correct placement and orientation of the two O-rings are critical to maintaining depth rating integrity.

The main O-ring has a round profile. It must be installed first.

The backup O-ring is flat on one side, and concave on the other. When installed, the concave side must face the main O-ring, as illustrated in Fig. 16.
Screen Shot 2021-10-14 at 9.56.04 AM.png
Fig. 16.    Orientation of the O-rings (a) main O-ring. (b) backup O-ring.

Use the plastic O-ring tool (included with the support kit) to remove the O-rings from the groove. The O-ring may need to stretch quite a bit as it is pushed off; this requires some effort but can be done by hand.

  1. Clean the groove thoroughly using a soft, lint-free cloth and compressed air if necessary.

  2. Select the proper O-rings and inspect them for damage.

  3. Lubricate with a very light film of silicone grease (included in the support kit).

  4. Install the main O-ring by sliding it over the electronic housings and popping it into its groove.

  5. Install the backup O-ring, ensuring that the concave side is facing toward the main O-ring.

  6. Once in place, inspect the O-rings once more for scratches and debris, and wipe away any silicone compound deposited on the carriage.

  7. Once the inspection is complete, close the instrument.