Can someone explain freezing

[oversea]

I see a lot of talk about reg freezing. I had just searched the subject but it seemed nothing specifically touched on it. I especially see mention about scubapro regs freezing (I have the mk25 s500). It seems to me it has to do with the first stage. I am switching over from an air2 to an octo to go with my backplate/wings. At first I was thinking of going with a better cold water reg (dive rite) but then realized it is the first stage that is the concern and regardless of second stage a freeze is a freeze.
Thanks for the info,
Justin

 

[SDAnderson]

Sealed first stage regulators are less likely to freeze than those that allow water to penetrate the first stage. Diaphragm regulators are less likely to freeze than those that use a piston design. In any event, a free-flowing first stage will cost you a lot of gas in a hurry. If you're diving in cold water (below 50F) you should seriously consider environmentally sealed diaphragm regulators. The MK25 is an excellent regulator but I don't believe it's suitable for cold water use, even modified. I have a couple of MK20's (essentially the same guts as the 25) that I like a lot but they don't go in cold water with me.

Second stage freeze-ups are less of an issue.

 

[oversea]

OK so I am in cold water and my reg freezes what now, no air? Reach for the pony and pray it's not the same?

 

[oversea]

I asked my LDS who is a SP dealer and asked about freezing. He said it is not a problem with them (as Jesus Christ himself could not build a better reg than a Scubapro)

 

[Warren_L]

OK so I am in cold water and my reg freezes what now, no air? Reach for the pony and pray it's not the same?

In the event of a reg freeze (both first stage or second stage) the reg fails open (i.e. delivers air). So unless your tank is almost empty at this point, typically you have some time to figure things out. Depending on the situation, if you're capable of making a safe ascent to the surface, you can do so, but you would generally signal to your buddy first that there is a problem and take appropriate measures.

 

[616fun]

I was diving last weekend and had a strange thing happen with my 2nd stage. I have a Cressi Air-Tech piston 1st stage (not that the 1st stage has anything to do with this event.)

While at about 50ffw and 38F water everything was going great. enjoying a nice chilly dive, then bam - a piece of ice flew out of the 2nd stage and slammed into the back of my throat. Didn't really cause an issue, but I'd give $10 to have a picture of the look on my face when it happened. It also made me wonder if I'm flirting with a possible freezing 2nd stage.

I'm confused about what happened. I didn't breathe the reg on the surface as I have heard that in cold weather that can cause issue.

Anyone have any ideas?

 

[Warren_L]

I asked my LDS who is a SP dealer and asked about freezing. He said it is not a problem with them (as Jesus Christ himself could not build a better reg than a Scubapro)

SP regs are excellent regs, but have been known to be prone to free flowing in cold water. I think this may differ somewhat from diver to diver, as a lot has to do with proper gas management under cold conditions. One of the main reasons why a reg would freeze up is due to high gas flow. As gas is drawn out of the tank through the first stage, it expands. Since this process is endothermic, it takes heat from its surroundings (the reg and the water around it). Normally, the flow of water through the reg can provide adequate heat, but if the flow rate of gas through the reg is too high, not enough heat is available and freezing may occur, resulting in a free-flow.

Proper gas management in cold water conditions can go a long way to preventing such free-flows.

 

[oversea]

In the event of a reg freeze (both first stage or second stage) the reg fails open (i.e. delivers air). So unless your tank is almost empty at this point, typically you have some time to figure things out. Depending on the situation, if you're capable of making a safe ascent to the surface, you can do so, but you would generally signal to your buddy first that there is a problem and take appropriate measures.

Forgive me if I am not getting it. The reg fails to deliver air so at this point I am holding my breath and trying to buddy breathe? What is the significance of the the tank being full or empty? I guess what I don't understand is "time to figure things out".
Thanks

 

[oversea]

SP regs are excellent regs, but have been known to be prone to free flowing in cold water. I think this may differ somewhat from diver to diver, as a lot has to do with proper gas management under cold conditions. One of the main reasons why a reg would freeze up is due to high gas flow. As gas is drawn out of the tank through the first stage, it expands. Since this process is endothermic, it takes heat from its surroundings (the reg and the water around it). Normally, the flow of water through the reg can provide adequate heat, but if the flow rate of gas through the reg is too high, not enough heat is available and freezing may occur, resulting in a free-flow.

Proper gas management in cold water conditions can go a long way to preventing such free-flows.

When you say "proper gas management" in cold water, what do you mean? Gas management means to me, watching your pressure and maintaining enough to do stops and possibly some surface time in rough water (I guess also being aware or your load)

 

[Warren_L]

Forgive me if I am not getting it. The reg fails to deliver air so at this point I am holding my breath and trying to buddy breathe? What is the significance of the the tank being full or empty? I guess what I don't understand is "time to figure things out".
Thanks

No problem. Reg failure usually means that the reg fails open, so air continuously bleeds from your tank in an uncontrollable manner. In this event, you can still breathe off the freeflow (which you would have learned how to do in your open water class). Depending on how much gas is still in your tank, there still should be time to take appropriate measures. If your tank is close to being empty at this point, you will have less time to work on the problem.

By figuring things out, what that means is to take appropriate action to get you out of trouble. Your buddy should be close by. Signal the problem to your buddy, who could donate a working reg to you, perhaps shut off your first stage, and ascend with you. If for some reason your buddy is not around, you need to decide what your plan of action might be - if you have a pony, you could use that. If you can ascend safely on your own, you could do that. A lot depends on your training and using your head to evaluate the situation and decide on a course of action.