‘Tis the season for freeze-flows!

[pt40fathoms]

Rick Inman once bubbled...

It's a sealed diaphragm, which the tech guy at DTW said should NOT have a 1st stage freeze issue. Humm...??

"should not" and "will not" are two very different things

Every reg will free flow given the right conditions; it's just that some are less prone than others. I use a Mares Abyys reg, and it has never free flowed. However if I cold soak the reg to temps below freezing and then jump in the water, I have no doubt that all I will see is bubbles after I take my first breath. Absolutely no one can make the claim that XYZ reg is completely incapable of a free flow. Only that it is able to withstand most conditions that can cause one. It is up to you to ensure that you follow some simple protocols when diving in conditions where the air temperature is below freezing.

If you live in an area that has below freezing temps, and still wish to dive this time of year. I highly recommend you sign up for the first Ice Diving course of the season. The things you will learn will be useful in the late fall when the water is still open, but the air is very cold.

This time of year is great, no boats, no algae, and very low probability of inexperienced divers stirring up the bottom. Don't let this time of year pass you up.

 

[cornfed]

pt40fathoms once bubbled...
The reason it stopped at 300 psi is most likely because that is close the upper limit of pressure that your second stage can handle and had the effect of stopping the free flow. Your first stage was most likely still non-functional.

Why would the first stage still not be working?

 

[pt40fathoms]

cornfed once bubbled...


There is an instructor near me that claims over using your inflator is the "best" way to cause a free flow.

I've seen that, but only with regs not designed for "cold" water conditions. They are usually have lots of plastic and not much metal. Its the metal that sinks the cold generated by high pressure air expanding to the intermediate pressure of your system. Plastic is an insulator of heat and cold, whereas metal is a conductor.

Some people like the new "lighter" regs, and that’s great that they have found something they like. They have to understand that those regs were designed for warm tropical condition, where you dive in a wet suit or no exposure protection at all. The problem starts when they try to use the lighter plastic regs in conditions that they cannot handle. Those conditions include but are not exclusively, dives where higher flow rates are expected such as when using a lift bag, dry suit or deep dives below 60 feet, dives in water temps that are below 45f., and diving in conditions where the air temperature is below freezing.

I'm not saying that plastic regs are bad, just that the do not perform well under conditions that the metal ones can operate in.

 

[pt40fathoms]

cornfed once bubbled...


Why would the first stage still not be working?

It's been my experience that the first stage will still be frozen open in a situation like this. The second stage will stop free flowing only because the tank pressure has dropped to a point at which the second stage can close and hold back the air. This is of course is dependant on the water temperature above the thermal, if in fact their was a thermal this time of year which in most cases their isn't.

 

[ScoobyPat]

Ok, I may not be a rocket scientist, but shouldn't it be possible nowadays to avoid the risk of free flowing while diving in cold conditions by applying heat to the first and second stage - somehow? I mean, we can design tiles that withstand super extreme temperatures, but are not able to heat up some air temporarily before serving the stages?

 

[Warren_L]

Yes, but a lot of the problems occur at depth, so how would you apply heat there? The adiabatic cooling that occurs as a result of the expanding gas must draw heat from the surrounding water. Adiabatic refers essentially to a closed system where there is no net gain or loss of heat. Technically, your reg at depth is not a closed system as you virtually have unlimited water to to draw heat from, but practically, it is in a closed system - due to the limitations of water flow rates to the reg. As such, if you draw more heat from the surrounding water (i.e. high gas flow rate) then the water cannot sufficiently heat the reg and a freeze occurs, resulting in freeflow.

 

[IndigoBlue]

pt40fathoms once bubbled...

This time of year is great, no boats, no algae, and very low probability of inexperienced divers stirring up the bottom. Don't let this time of year pass you up.

Hear, hear!

I will drink to that. From a thermos, of course. Hot green tea sweetened with maple syrup. My favorite warm-the-bones recipe for a cold dive day.

 

[cornfed]

ScoobyPat once bubbled...
Ok, I may not be a rocket scientist, but shouldn't it be possible nowadays to avoid the risk of free flowing while diving in cold conditions by applying heat to the first and second stage - somehow? I mean, we can design tiles that withstand super extreme temperatures, but are not able to heat up some air temporarily before serving the stages?

Because you're either have to make them out of something which would make those stupid titanium regulators look cheap or apply an external source of heat during the dive. Neither option is very good.

 

[pt40fathoms]

ScoobyPat once bubbled...
Ok, I may not be a rocket scientist, but shouldn't it be possible nowadays to avoid the risk of free flowing while diving in cold conditions by applying heat to the first and second stage - somehow? I mean, we can design tiles that withstand super extreme temperatures, but are not able to heat up some air temporarily before serving the stages?

You’re very close to what the designers of regs are doing now in order to help prevent free flows at deeper depths where the demand for air is greater, and in colder climates where freeze up occurs from below freezing air temps. They approach this problem with a combination of three solutions. First they choose materials that conduct heat efficiently and are strong enough to operate at the high air pressures used for scuba. Secondly they try to maximize surface area in order to grab as much heat as possible from the surrounding water. Third and most difficult, they try to design the first stage so that it will still operate with "some" icing. Almost all free flows are due to the first stage failing to properly regulate the air pressure delivered to the second stage. This is not to say that a second stage never free flows by itself, they can. However a second stage free flow is most often due to poor maintenance, miss adjustment, or a poor design. In the case of diving in below freezing temps, a second stage can free flow if it is iced up and the purge button is stuck in. This is usually very obvious and is cured by simply immersing the second stage for a few minutes in the water, thawing the ice and releasing the button.

So in short, yes they are applying heat to the first and second stage. That heat is coming from the water you are diving in.

 

[MikeFerrara]

Interesting thread.

The only freezing I've had with my sealed diaphragms has been at the surface before the dive if the reg is wet from a previous dive or a purge gets bumped. A few minutes thawing time (in the water) fixes the problem. The first stage should be dry and the air in the tank should be SUPER dry. There shouldn't be anything to freez. That leaves the second stage which always gets wet and will freeze if it gets cold enough.

Some second stages are more prone to free flown than others but in out group using Zeagle and apeks regs we haven't ever had a free flow at depth in hundreds and hundreds of cold water dives.