Speaking of switching regs from one tank to another

[Angie Reim]

Some long time sidemounters I know (who don't do it for show!) use an H-valve on one of their tanks with an extra pressurized reg attached, kinda eliminates the having to switch first stages deal.

Safe diving,

Rich

That's a good idea. Especially if you are doing a lot of the 'might as well be solo' kind of diving. Spare 1st stage. Redundancy.....duh. 8)

[Jim Fishback]

I have not had to change regulators underwater but I have thought about it. When Turning the GAS back on I would do it slowly and push and release the purge button a couple of times. So any water that got into the First stage with blow on through. If you hold it down it could freeze up on you. Also I would expect the SPG to go bad. That could happen a couple of dives later. I would have the regulator service.

[lonestarfl]

Jim,
I don't put a pressure gauge on the back up regulator. If I have to do a switch underwater...I am on the way OUT. Monitoring the gas is not that important...You've got what You've got. Know what I mean.
Lee

[Rob]

A buddy and I had to do it once while doing our 70 foot deco stop in a raging current after doing a 320 ft wreck dive. It wasn't fun and it really took both of us to get it accomplished. Since he needed that deco gas we didn't have a choice. We took the reg from his 120 bottle and moved it to the 70 bottle. I was putting the 'good' reg now filled with saltwater on the tank and was really hoping that it was going to work. We use all DIN for everything so once I had the reg screwed in about half way I cracked the valve far enough open to get some positive pressure in the first stage, while purging the second finished screwing the reg in. Opened the valve all the way slowly and finished purging the water out. He said it breathed a little sluggish through deco but not too bad all things considered.

After getting both regs rebuilt he showed me the orings and seat out of the bad one, one oring was torn and the seat had a serious indentation from the knife edge of the piston. We figure that he had bumped the second stage at depth and purged the reg allowing the water pressure to force the piston into the seat. On an interesting note there didn't appear to be any water in the pressure guages and I believe he still uses them today. This happened about three of four years ago.

[jason]

An H valve with the extra regulator on one tank is cheap insurance.
As to the original question...has a regulator switch ever been required underwater on a dive?

Assume for a moment (purely hypothetically of course) that the tank that was drained (due to being stuck in high flow) had an H valve on it (probably because there was some no-mount stuff that was being pushed...) And then the remaining tank has a reg that got shell material in it while squeezing through another restriction in high flow (and clearing that second restriction might be slightly hampered by the H-valve dragging in the sediment in the high flow). In this fictional scenario, the diver might have thought to put panty hose over their reg to prevent this from happening, but given the high flow and work rate - the panty hose might make breathing a bit harder and cause the diver to remove the offensive hose.... Let's make this scenario happen in about 160 feet of water just to keep the discussion interesting. This is all purely hypothetical....

[Limestone Cowboy]

What I am pondering is, How many incidents have involved actually switching a reg from one tank to the other? As in how many people have done it because they "had" to, not for testing...??

I had to assist a dive buddy at the Nest swap regs between his 20 and 70 ft bottles. Yokes are much easier than din when you have to do this. Switch went fine, regs survived, and SPGs survived. Of course, he just went to back gas to do this, so it wasn't rushed. Saved him probably close to 30-45 minutes of extra deco.

Drew

[MikeH]

This one time....at band camp....

Mike

[Gary]

if you're diving sidemount (for real, not just to be showy) and get shell material or gravel under one of your diaghrams - your going to have a full tank of gas that is inaccessible. Now suppose you got stuck and drained the majority of your other tank while extricating yourself and you might be in a position where swapping regs underwater is looking a bit more like a good idea - no amount of regulator servicing is going to help prevent that situation....

Meaning one of your regs breathes a little wet? Hardly inaccesable.

You still have 2 tanks with breathable gas in them regardless of how inconvienient it is to get at that gas. Breath one reg (since one is all you should need to get out safely). If you consider it worth the extra effort remove the face plate on the other and clear out the piece of debris that is the problem.

People have developed all sorts of extreme senerio situations and fixes but basically unless both tanks explode you've still got air to get out.