By the end of Practical Application, Part Three, the student should be able to:
3. Above the surface (not underwater), but simulating being underwater by wearing a mask and breathing only from regulators, demonstrate the procedure for replacing a malfunctioning regulator on one main cylinder with a functioning regulator, with the assistance of a team mate's gas supply or the use of a stage/deco cylinder.
4. Above the surface (not underwater), but simulating being underwater by wearing a mask and breathing only from regulators, demonstrate the procedure while replacing a malfunctioning regulator on one main cylinder with a functioning regulator from the other main cylinder, with no use of a third gas source.
Recommended Sequence- Replacing a Malfunctioning Regulator with a Third Gas Source
1. Demonstrate the skill.
2. With the mask on and breathing from either regulator (instructor's choice), on signal of a simulated freeflow, the student shuts down the valve and switches to the other cylinder.
3. The student signals "share gas" to team mate, who provides the long hose (for the exercise, this cylinder may be standing nearby). The student switches to the team mate's long hose.
4. The student depressurizes and removes the simulated malfunctioning regulator. [Note: An actual freeflowing regulator would likely already be depressurized.]
5. The student shuts down the functioning regulator, depressurizes it and transfers it to the other cylinder.
6. After repressurizing it and confirming proper operation, the student switches to the functioning regulator and returns the team mate's long hose.
This skill should progress with little difficulty because the diver has a gas supply (which is the primary point).
Recommended Sequence- Replacing a Malfunctioning Regulator without a Third Gas Source
1. Demonstrate the skill. Emphasize that in real life, you would only get one chance to do this right, so be slow, deliberate and methodical.
2. It's recommended that you have each student conduct the prior skill, then this skill, because they will already have all the equipment in place.
3. On signal of a simulated freeflow, the student shuts down the affected regulator and switches to the other regulator.
4. The student carefully removes the malfunctioning regulator while breathing from the working regulator.
5. Optional step: The student carefully removes o-ring from malfunctioning regulator (DIN) and puts it some place where it won't be lost (inside wet suit cuff, on a clip, etc.), yet is immediately retrievable, in case the other o-ring gets lost during the regulator switch.
6. The student closes valve to functioning regulator until it is open only enough to breathe. (During your demonstration, point out that the deeper you are, the more open it has to be.)
7. When ready, the student closes the valve and inhales from the regulator to depressurize it. Keeping the second stage in the mouth, the student methodically transfers it to the other cylinder, exhaling very slowly, opens the valve and begins breathing.
8. Most students accomplish this on the first try, but be prepared for some who need more than one attempt to succeed.
9. After a successful transfer, as an option, you can have the student "lose" the o-ring from the functioning regulator after removing it. With only the single breath, the student replaces it with the spare from the malfunctioning regulator, then mounts the first stage