Replacing the O-rings

Care for the O-ring is the single most important item of maintenance. A water leak can damage the RBRfermata beyond repair. The battery canister seal depends upon its O-ring, therefore proper O-ring maintenance is crucial.

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

Location of the O-ring

The O-ring is located in the battery-end cap, as shown in Fig. 7. To access the O-ring, Open the RBRfermata.

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Fig. 7.    The location of the O-ring

Inspecting the O-ring

Visually inspect the new O-ring for nicks and scratches before installing it. Pay attention to the following areas:

  • 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

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

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

Do not return the old O-ring to the battery canister. If you remove the O-ring from the RBRfermata 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-ring

Do not use metal screwdrivers or any other metal tool. They may scratch the O-ring groove and render the end-cap useless.

  1. Use the plastic O-ring tool (included with the RBRfermata) to remove the O-ring from its 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.

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

  3. Select the proper O-ring and inspect it for damage.

  4. Lubricate the new O-ring with a very light film of silicone compound (included with the instrument).

  5. Install the new O-ring by pushing it into place and popping it into its groove.

  6. Once the new O-ring is in place, inspect it once more for scratches and debris, and wipe away any silicone compound deposited on the end-cap.

  7. Once the inspection is complete, Close the RBRfermata.

O-rings on | deep variants

The | deep variants of the battery canisters use two O-rings. One is the main O-ring, and the other is the backup. Both are required to protect the RBRfermata from flooding.

Orienting the O-rings on | deep variants

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 highlighted in Fig. 8.
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Fig. 8.    Orientation of the O-rings. (a) Main O-ring. (b) Backup O-ring.