1st stage switch; tank valve breathing

Jim Lapenta:

No spg as it will surely get ruined. Regs are easy and cheap to rebuild. Spg's get expensive.

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DaleC:

No 1st stage removal involved - that only happens in the movies.

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Johanan:

If I understand correctly, by "regulator switching" it is meant removing the 1st stage from one cylinder and installing it to another cylinder underwater. Have you ever tried to do that?

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PADI Tec Sidemount:

When might you move a regulator from one cylinder to another during a dive? How do you do it with and without a third gas supply?


Because your valves are in front of you, it is feasible to move a functioning regulator from one cylinder to another to replace a malfunctioning regulator.
(This can be especially important in decompression diving when you only have a single cylinder with a particular gas.)


1. The functioning regulator will need a complete overhaul afterward because it will get water in it, but it should function for the rest of the dive.
a. Underwater switches tend to ruin SPGs because once water gets in them, it is hard to remove, and will corrode the internal working in a matter of weeks or months.
b. You will practice these techniques with your valves and regulators out of the water to avoid equipment damage.


2. If you have gas from a third cylinder (a team mate shares gas or stage/decompression cylinder), the swap is straightforward.
a. Depressurize and remove the bad regulator from the destination cylinder. You can normally leave it tucked in the cylinder bands so you don't lose it.
b. Breathing from the third gas supply, depressurize the working regulator and transfer it as you would at the surface.
c. Expect to get a little water with the first breath (not usually much).

3. You can move a regulator without a third gas supply, but doing so requires being calm and taking your time.
a. Stabilize yourself in such a way that you can focus entirely on the switch.
b. Depressurize and remove the malfunctioning regulator. Make sure the valve is completely clear and ready for transfer. Check inside to be sure the o-ring from the regulator (DIN system) didn't stay behind by accident.
c. Close the valve supplying the good regulator almost all the way, but leave it open enough to keep breathing.
d. When ready, close the valve and inhale to depressurize the regulator. Keep the mouthpiece in your mouth, exhaling very slowly (remember to never hold your breath). Remove the first stage (be sure the DIN o-ring comes with it), transfer it to the other cylinder and open the valve.
e. Being slow, sure and methodical, and checking the details, will be faster than if you rush.
f. Again, expect some water with the first breath.

4. Obviously, it is better to have a third gas supply if circumstances require you to move a regulator.

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PADI Tec Sidemount Instructor Manual:

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

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Johanan:

What would be the effect of water entering the 1st stage and would an ACD (automatic closure device) be of any help?

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Johanan:

Is breathing directly from a tank valve similar to breathing from a freeflowing regulator that is taught in the OW course?

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PADI Tec Sidemount Knowledge Development:

4. What is "feathering" and how do you do it?

Another option you have in sidemount is feathering, which is using the cylinder valve to control a free-flowing regulator.


1. This is feasible in sidemount because you have ready access to the valves.
2. If one of your regulators begins to freeflow, follow these procedures for feathering.
a. Switch to your other regulator (if breathing from the freeflowing one) and shut down the valve to the freeflowing regulator.
b. While still on the functioning system, practice just cracking and then closing the valve on the other until you get a feel for releasing a controlled, slow but adequate flow.
c. With the valve closed, return to the malfunctioning regulator. Clear it and just crack the valve to get a breath. Do not block the exhaust valves; allow any excess gas to escape.
d. Close the valve as you exhale. You can also let the gas flow continuously, which is easier, but does not conserve as much gas.
e. Use the procedure while you still have ample gas in the functioning system. Keep the working second stage readily accessible in case you start to have difficulty controlling the flow.
f. Typically, you switch to the functioning system for your final ascent and procedures on the surface

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