Owner`s manual

O ptima FX Owner’s Manual

Ch. 2 Pg. 3

and have the hoses removable, others have the T-Pieces removable but have the hoses

permanently connected, but the O2ptima is different in that the hoses are removable and the T-

Piece is removable from the counter-lung. This design allows the easiest cleaning, maintenance

and testing of the various components.

Automatic Diluent Addition Valve

The ADV is used to connect the inhalation counter-lung to the

canister and to the DSV inhalation hose in the same manner as the

T-Piece but without the baffle. The ADV has a built in demand

valve that is triggered by negative loop pressure against a

diaphragm in the same manner as a standard second stage. The

O2ptima’s ADV design can feed diluent directly to the DSV in

order to provide a fast method of receiving a known gas and to

supply additional gas to increase loop volume. The ADV fittings

are coded RED to indicate the inhalation side of the loop and are

reverse threaded (to tighten counter-clockwise).

This valve should never be used without the addition of a “trombone” style gas shutoff valve.

Most divers will begin the dive with the gas shut-off valve in the open position allowing the

ADV to function normally during descent. Once at depth, the ADV may be disabled by sliding

the gas shut-off valve to the closed position. This allows the diver to make small depth changes

without the ADV firing. Another advantage of disabling the ADV at depth is that it easier for

divers to recognize small leaks and an oxygen delivery failure because loop volume would

decrease. The loop volume at a constant depth should not change on a properly functioning

rebreather.

Manual Addition Valves

The manual gas addition valves are dry-

suit style valves and use standard LP

inflator hose connectors. These valves

allow the manual addition of diluent or

oxygen and permit the use of off-board

gas supplies. The diluent valve uses a

center push button to add gas while the

oxygen valve uses a side push button. It

is essential not to confuse the oxygen

components with their diluent

counterparts. The entire oxygen

delivery system should be maintained in an oxygen clean state. The oxygen MAV is located on

in exhalation counter-lung on the diver’s right hand side, while the diluent MAV is located on

the inhalation counter-lung on the diver’s left hand side.

Diluent Addition Valve

Oxygen Addition Valve