Switching regs from one cylinder to another U/W?

[rjack321]

I don't understand why the SPG would be toast???

Bourdon tube pressure gauges work for years with salt water. Granted, the flow-limiting orifice may get blocked but is easily cleaned. Probably not a great idea to use on pure O2 bottles since it would be difficult to oxygen clean.

If you ever brought the reg into freezing weather (ever again since you can't dry out the inside of the tube) ice forming inside the tube will change its shape and render it inaccurate, through at least part of its range.

 

[syntaxerrorsix]

If you ever brought the reg into freezing weather (ever again since you can't dry out the inside of the tube) ice forming inside the tube will change its shape and render it inaccurate, through at least part of its range.

Why wouldn't the water be expelled when the pressure was let off?

 

[parzdiver]

Okay, I'll be more specific. Say I have a Suunto Cobra 2, on a factory quick disconnect (mine) or an Aeris Atmos hoseless (would if effect the sender? - wife's)?

And I apologize if this is a thread hijack.

There is the potential for water to get into the preasure sensor part of the computer or transmitter, and the potential for it to cause corrosion and issues. Any time water is introduced inside the first stage, there is potential for problems.

That being said, changing a reg while underwater is a rare thing. It is also done in more extreme circumstances that damaging or losing gear is better than losing your life. It should be avoided unless necessary.

 

[ScubaTigress]

better to lose the equipment than your life...... but, it shouldn't ever have to be necessary to get into such circumstances.

 

[Paulmal]

This is more prevalent in tec diving, I have never heard of anyone doing it during a rec dive.

In tec diving most often it is because of a failure of a deco reg, but it is an option when in side mount but you require a buddy for sidemount.

 

[Akimbo]

I concur that the likelihood of changing regulators underwater outside of a Sea Hunt episode is an extremely remote option. I took the OP’s question more as a theoretical one of possibility rather than part of a planned emergency procedure. It the end this discussion is more about regulator valve design than anything else.

If you ever brought the reg into freezing weather (ever again since you can't dry out the inside of the tube) ice forming inside the tube will change its shape and render it inaccurate, through at least part of its range.

Interesting point. I am not sure it would qualify as making the SPG toast since they have pretty course precision anyway. From a purely technical point, you could dry a bourdon tube in a vacuum (bell jar so it doesn’t under-pressure the movement). It would leave salt crystals behind but the quantity would be too small to be harmful.

This is more prevalent in tec diving, I have never heard of anyone doing it during a rec dive...

It would have to be a limited overhead dive, otherwise it would take longer to change regulators than just swim to the surface.

 

[stevensamler]

I understand you should never run out of gas. You should always have a buddy who has gas. But.....

If for some unforeseen reason, i.e. catastrophic redundant failure occurs can it be done? While underwater, can you safely/effectively remove a regulator from one cylinder and put it on another cylinder and be able to safely breathe? if so, what are the consequences to the regulator? What servicing would need to be done?

For example, your buddy gets trapped at depth, you have extra cylinders in the boat, but no spare regs. Time is of the essence, and you determine the extra time in switching cylinders on your gear is a bad choice.

Or you have a failure of your deco bottle reg and have to use your primary reg set.

I've just finished PADI Rescue, and "what if's" are occurring to me. Thanks for your input.

Reg exchange underwater used to be a skill that was taught ow nasds back in the 70's , i did it for my jr cert along with rescue.

 

[elan]

Aqualung regs with the acd should stay dry and save the SPG. I would still service it after the dive.

I cannot see how ACD would block all the water. When you screw the reg on the other tank there will still be some water in the connection between the reg and the valve. Once the valve is pressurized that water will be pushed into the reg regardless.

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I have seen it done. My buddy had a malfunction with one of his deco regs (two deco gasses) and was able to switch it at depth. FWIW I believe he was using Hollis regs. From what i understand a piston reg theoretically will handle the water better than a diaphragm, but the Hollis are diaphragm and handled the situation just fine.

It's not that it will not handle the situation. The issues is that in diaphragms and flow through piston there are spaces where the gas does not flow but just transmits the pressure (balancing chamber passages, piston stem and piston head area). If the water gets into those spaces you will have hard time getting it out completely without dis assembly.

In a flow through piston if you get the salt water in the reg you can basically open all ports connect a garden hose to the DIN and wash it inside Connect it to the tank and blow the air through and dry it out. Not that I would recommend it to do... but flow though ones do not have dead spaces.

 

[Necklinsberg]

Maybe I've been out of the water too long ... but if you are going to go through the effort of lugging an extra tank along on a dive, or placing a back-up tank somewhere ... why wouldn't you go through the minimal extra effort of placing a regulator on that tank?

 

[PfcAJ]

Maybe I've been out of the water too long ... but if you are going to go through the effort of lugging an extra tank along on a dive, or placing a back-up tank somewhere ... why wouldn't you go through the minimal extra effort of placing a regulator on that tank?

Of course. Carrying a tank w/o a reg is dumb.

But, if you're the type of diver that maybe uses more than 1 deco gas, or more than 1 stage, if a reg breaks you can swap out the broken reg underwater. Now, you've got 2 flooded regs to deal with post-dive.

Fwiw, sometimes the SPG goes tits-up, sometimes it doesn't. I can't even begin to count the number of times I've had a stage reg accidentally de-pressurize and come a little loose underwater (freshwater dives, here). I've only had just a few SPGs ever get water in them, and I don't do anything special post-dive as far as rinsing, cleaning, rebuilding, etc. I just toss it back in the box-o-regulators and carry on. I would not be a happy camper if this was a thing that happened on ocean dives with any frequency.