sharing air in cold water

[18diver18]

Buy a Apex reg and never have a free flow again!

 

[GrumpyOldGuy]

Buy a Apex reg and never have a free flow again!

Hmm.... Why does Apex devote pages 22 and 23 in their manual about the special steps to take when diving cold water to prevent freeze flows including verifying you have dry air (how), preventing premature contact with the water, keep gear warm before dive, breathing with it above water, using purge, removing the regulator from your moth and avoiding heavy exertion during the dive.

I am not knocking APEX, they make some fine gear and may be less prone to free flow, but the laws of physics still apply and they can still free flow or they would not be putting all these dire warning in the manual.

 

[elan]

From all cold water regs I have seen Apeks freeflowing the most here
It might have something to do with agressive tuning or complacency on the diver's side.
But thinking "I have Apeks(or any other reg) so Im immune definitely does not work.

 

[Ayisha]

Buy a Apex reg and never have a free flow again!

Apex regs certainly do freeflow around the Great Lakes, although I've seen Scubapro freeflow the most. I have a Sherwood Blizzard, and I've never heard of or seen a Blizzard freeflow, but it could happen. The newer Sherwood SR-1's have been getting a reputation for freeflowing around here the last couple of years and I've been around for a couple.

Making a reg "too" easy to breathe also makes it more likely to free(ze) flow. Tuning is everything.

Someone asked if doubles are standard. I'd say they're not exactly standard, but definitely very common around the Great Lakes, ie) very cold water diving. I carry a 19 cf pony bottle, which is fairly common as well. Some sort of redundant gas is pretty common in very cold water diving.

 

[lowviz]

scuba andy,

I just noticed that this thread is in basic discussions. Free flows and freeze-ups can be confusing due to the different ways you end up with pretty much the same effect. I'll try to stay general and start to sort them out. (I'll not add the evasive tactics / solutions or this would become a hijack.)

Anyone feel free to correct/expand in the scope of the OP's concerns:

Primary reg (the one on your tank) freeze:
Water inside the reg can freeze due to the expanding gas. The resulting ice sometimes interferes with the intermediate pressure regulation hardware. This INTERNAL ice build-up usually results in an increasing overpressuring of all the low pressure hoses on this primary. In very cold water, consider this as a serious warning if you somehow happen to notice a slow stream of bubbles coming out of one of your secondary (the ones you breathe) regs.

Secondary reg freeflow:
Commonly seen, just the venturi effect holding you secondary reg's mechanism open so gas can continue to roar out. No big problem.

Secondary reg freezes:
Slow bubbler. Can look exactly same as a primary reg freeze. Ice buildup in your secondary is causing a slow stream of gas to leak by, usually gets worse.

freeze freeflow. Depressing the purge on a wet secondary in very cold temps (in air or even U/W) can cause the reg to freeze open. Looks like a venturi freeflow, but much harder to resolve. Most exciting. Think about this when filling lift bags in very cold water.


Now for a direct answer to your OP: If you have two divers on one reg, both try to stay calm and stagger your breathing. If you are truly sharing air, this is not an issue. The second thing that you can do is to adjust inflation with short bursts that are spaced between breaths. The whole idea is to keep the demand on the working reg as low as possible. Note that inflating between breaths is a good idea anytime.

 

[jaycanwk]

I would suggest that if your diving "cold" water, as in below 10c or close to freezing then you really shoud be using a regulator that is designed specifically for cold. That means one that has an enviromentally sealed 1st stage, preferably diaphram, but the sealed piston, like the Sherwoods are just fine, and a 2nd stage that is idealy all metal or, if plastic, with heat sinks over the air barel. Not that it isn't possible, but it is far less likely to get a free flow with those regs. I dive the Great Lakes and have never had a free flow yet using a reg of that description and that is while both breathing hard and sharing air. I own both a Sherwood Blizzard and a Mares Proton 42 metal, so I can only speak to those. I still sling a 30cf pony just incase (I have the Blizzard on the pony)

 

[scuba andy]

Im fine that the discussion has opened up.

Particularly as there appears to be only a few things to consider in the limited scenario I raised: 1. stay calm and breath slow/deep, 2. use manual inflation of BC if appropriate, 3. possibility of staggered breathing and 4. the possibility of buddy breathing if both are calm, trained and competent.

-Other than that, it would seem avoiding the scenario in the 1st place is altogether better. And that would be a matter of prevention and redundancy (ie.: good procedures, appropriate kit).

Thanks.

 

[rhwestfall]

Im fine that the discussion has opened up.

Particularly as there appears to be only a few things to consider in the limited scenario I raised: 1. stay calm and breath slow/deep, 2. use manual inflation of BC if appropriate, 3. possibility of staggered breathing and 4. the possibility of buddy breathing if both are calm, trained and competent.

-Other than that, it would seem avoiding the scenario in the 1st place is altogether better. And that would be a matter of prevention and redundancy (ie.: good procedures, appropriate kit).

Thanks.

At 0-24 dives, you have knowlege/understanding beyond many.... now, make sure and execute it!

 

[FoxHound]

prevention can be as simple as tuning down the reg a bit.

Any reg can free flow....its a fact....there is, however, lots you can do to prevent it as you have already seem to have a pretty good understanding!