Prior to installing the DSV it is recommended to visually inspect the mushroom valves on both sides of the unit. Ensure that there is no debris or excess lubrication on the sealing surface underneath the mushrooms. The mushrooms should be soft and pliable and sit flat against the valve cage. If the mushrooms do not sit flat or appear swollen, brittle, or damaged in any way, they must be replaced before diving. Faulty mushroom valves can cause hypercapnia, leading to severe injury or death.
Confirm that the mushrooms are sealing correctly by covering the exhale (right) side of the DSV with your hand and exhaling gently into the mouthpiece. There should be no air leaks heard or felt. Next, cover the inhale (left) side of the DSV and inhale gently. Again, there should be no leaks.
Once you have confirmed proper mushroom valve function, ensure that the O-rings and O-ring sealing surfaces are clean and lightly lubricated (See Figure 25) and then install the DSV.
It should be oriented with the white locking buttons at the bottom with the DSV in the diver’s mouth.
The lever should also point down when the DSV is closed. Orientation of the DSV is critical as it determines the gas flow direction through the loop. The Optima CM will not function correctly if the DSV is reversed.
To install the DSV, connect the exhalation loop hose into the exhale side of the DSV by pushing the connector firmly into place. You may need to twist the lock ring slightly to align the tabs on the ring with the groves in the DSV body. With the hose connector fully seated, push and turn the lock ring clockwise 1/8 of a turn until the white locking button snaps into the notch on the lock ring. Ensure that the lock ring is locked and that the hose cannot be pulled back out. Repeat the procedure to connect the inhalation hose to the inhale side of the DSV.