Primary and Secondary Regulators w/ dual Sidemount

[PhatD1ver]

Sidemount teams often don't even bother with a long nose. Each diver manages his gas so that he can safely exit on either tank. In addition, it's possible to switch a working regulator to the other tank on a breath hold or feather the valve on the tank with the problem. Obviously, if you're diving as a mixed SM/BM team you will have a long hose for your BM partner.

So, I'm just getting my gear together and learning SM, but you can switch regulators underwater? I thought the 1st stage would flood? (which is why we have dust caps and make sure they are seated before we rinse them?

I'm sure I'll be corrected, thanks in advance.

 

[Patoux01]

It's just not recommended, but the water will get out eventually so you might get a few wet breaths at the beginning maybe and that's it.

When you do that, it's usually plan E at least, so at that point you really don't care if your gear will survive the dive or not, you're only aiming at saving your ass.

 

[tbone1004]

it is last resort. I will go to bare tank breathing before I have to swap first stages, but that's not exactly recommended either. First stages will have to go in for a rebuild after a stunt like that and you may well have to get new SPG's

 

[victorzamora]

So, I'm just getting my gear together and learning SM, but you can switch regulators underwater? I thought the 1st stage would flood? (which is why we have dust caps and make sure they are seated before we rinse them?

I'm sure I'll be corrected, thanks in advance.

You can switch regulators. However, it's more of a parlor trick than anything. Feathering the valves, if done right, nets you 90% of the air you would've had anyway with FAR less effort. The only time I see switching regs as a good idea is if you're on deco, have another reg you're not using to switch with, and you've got a lot of deco ahead of you. I've feathered my O2 bottle for my entire 30+minute deeco before, just for fun (deco gets VERY boring, I'm afraid of having to do "serious" deco).

Also, check your dust cap. The VAST majority of dustcaps do little other than shield the 1st stage from dust. I got chewed out at a dive shop I worked at for not putting the dustcap on one of the regs. I then showed them how useless the little dustcap was. They're typically not waterproof. The ones that are actually waterproof are different in design and seal against the DIN o-ring and screw on. Even some of the screw-on caps aren't water-tight as they seal against the metal and not the o-ring. Yoke first stages (which you shouldn't really be diving in sidemount) seem to seal with their standard dustcaps, but overtightening often breaks that seal. Water in your first stage really isn't that big of a deal if it's clean, fresh water and you're pumping dry air through it. Salt water in my first stage would mean it ends up in pieces on the table that night. Repeated fresh water in my first stage would mean the same thing.

 

[mddolson]

When re-attaching a reg submerged, depress the purge & turn on valve slowly.
Water & air follow the path of least resistance, which is though 2nd stage, not metering hole in HP hose to your gauge.
I would follow up with a tear down (if in salt water).

Mike D

 

[nakatomi]

Also, check your dust cap. The VAST majority of dustcaps do little other than shield the 1st stage from dust.

The Apeks caps are waterproof when screwed on completely. I had three sets of mine sitting on the bottom of the Mill Pond for almost two hours before they were salvaged, with their dust cap on.
There was no water in the first stages.

 

[victorzamora]

The Apeks caps are waterproof when screwed on completely. I had three sets of mine sitting on the bottom of the Mill Pond for almost two hours before they were salvaged, with their dust cap on.
There was no water in the first stages.

That's good to know. My dust caps seal as well. On the Hollis regs I had, they were barely dust caps. They were these little rubber condom things that slid over the DIN threads. To reiterate, though, screwing onto the DIN threads and actually sealing water-tight are very different things.

The other thing to mention is depressing the second stage purge buttons. That can cause your regs to flood no matter what your dust cap is doing!

 

[tbone1004]

screw on din covers seal against the oring just like the valve does, and the rubber balls that go inside of the yokes, not sure what brands have these but Apeks work very well and will actually seal the first stage opening. Many actual "dust caps" are just those stupid condom things that won't keep anything out.

 

[victorzamora]

Many of the "screw-on" dust caps don't have a hole on the inside center of the cap to accomodate for the inner metal piece inside the o-ring that protrudes outwards. These screw-on dustcaps seal against the metal, which is NOT a water-tight seal. The ones that have the extra machining inside of them actually seal against the o-ring, which makes them water tight. I've seen many caps without the extra machining.

 

[TotDoc]

I must admit, i now can't be sure, as whenever i practice OOG drills i use the purge as a standard part of the process.....

Interesting comment here. I never really thought about that aspect of an OOG drill until I had an issue with an OOG situation the other day with my girlfriend. We were doing full facemask dives, and I was having her practice removal and replacement of the FFM before we did our dive in some shallow water, since it had been a while since she dove that rig. She was struggling with getting the mask to reseal and clear and ran out of breath, so she ditched the mask and I handed her my long hose. She apparently had always just did a big breath to clear regs and never did the purge, but she didn't have enough air in her lungs to clear the reg, so she got a bit of a wet breath and bolted to the surface. She's a rather experienced diver, and neither one of us had really considered the bad muscle memory we had been establishing by not repeatedly doing OOG drills using the purge, and in that instance, it made a big difference, very much a surprise to both of us. Anyway, I'm glad we figured it out in shallow water during a drill and not in a real emergency...even though we tried making a real emergency out of a drill in that circumstance! Anyway, I just wanted to share my experience on that one...it's purge only for clearing on OOG drills for now on for me!