Nikon D80 user manual Air Lock, Pressure release plug, Opening levers

4.1Air Lock:

The body and lid are designed with the Air Lock System “no clip” closure arrangement. Testing has shown that this arrangement allow the water to exert an even pressure on the O-ring, Increase the reliability of the watertight seal.

4.2Pressure release plug

To open the housing, the pressure release plug must be first unscrewed and then

pulled out all the way (Counter-clockwise)(Fig 1). This provides a passage for the air to pass though and eliminate the pressure different between the inside of the housing and the ambient. The plug consists of an internal double O-ring seal on the stainless steel slide shaft.

These internal O-rings form the watertight seal. There is also a large outer O -ring under the knob. This O-ring serves to prevent contamination of the slide shaft, with dirt, salt etc., and is not required for watertight integrity. If this O-ring should become detached, it can simply be pushed back in place.

(Fig. 1) Open Housing Procedure

4.3Opening levers:

After unscrewing and pulling out the pressure release plug, the lid can be opened. To overcome the friction of opening, use lever (Fig. 2) to push against the lid with a cam action. Be sure they are inserted all the way flat to the housing before turning to avoid damaging the protrusions on the lid. The body has four holes on each corner edges for opening. Gently lever off the lid with the supplied opening lever (Fig. 3) taking care not to twist the lid excessively. The lid should be opened keeping it approximately paralleled to the body at all times, turn first one corner a little, then the other a little, and repeat again until the lid is opened. Remember to unscrew and pull out the pressure release plug all the way first, otherwise the air pressure will resist attempts at opening. Lay the lid on a flat stable surface after opening.