My reg freeflowed at 80 feet

[Jetwrench]

may be a "dry bleed" reg


Genesis, you are right! And yes, I have had buddies tell me my first stage is leaking until I explain what the bubbles mean. You may also want to know that my other reg(magnum), which is now on my pony, gave me my first freeflow experience. It has the same type first stage, but on that one dive I didn't follow the rule I was taught. My bad.

On your other point about rapid descents, I haven't run into that problem and didn't know there was that issue. I'll keep it in mind in the future. I'm not sure what you consider quick descents, but I have done several dozen dives in what I would say were farely quick with no problems. I, in fact, have gotten used to cranking the restrictor adjustment down cause it just feels more right. Thats just me.

I guess the answer is what you dive with and where you dive will set the requirements. Nice pickup, Genesis. I forgot to add that to my post, so you obviously know your stuff. Dive Safe!

Jetwrench

 

[Bob3]

Dang, some great detailed info.
I did a "Regulator Freeze 101" that explained things in plain lingo: http://www.scubadiving.com/members/divetips.php?s=153
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Regulator Freeze 101

There's no set temperature where regulator freezes occur; the colder the water, the more likely it is to happen. Some manufacturers use 40º F (4½º C) as an arbitrary number to define conditions where icing may possibly commence.
Both saltwater AND freshwater can get down to 28º F (-2.2º C) and not turn solid if kept moving, such as in a heavy surge or current.
The most common type of regulator freeze-up is the first stage. Unless you're using an environmentally sealed reg, there is water inside your first stage. That water freezes from the air absorbing heat upon expanding (compliments of a similar set of physical laws that make your referigerator work).
The result is overpressurization of the second stage, resulting in a free flow. Most folks THINK their second stage is frozen up, but it's actually the first stage that causes the second to malfunction.

Second stages do freeze up, tho mostly on the surface from breathing in them when air temp, wind chill, etc is below freezing. Simple solution: Don't stick the reg in your mouth until you're underwater.
The other type of second stage freeze is much more rare, in that the water temp almost always has to be below freezing & you have ice build up inside the regulator from breath condensation.
This can happen to even the BEST freeze-proof regulator if the conditions are right.
Hint... double hose regulators don't have this problem. To date, the most all-around freeze-proof reg is still the double hose.

Tip for folks using a separate bottle for drysuit inflation: Install a pop off (overpressure) valve on an LP port of the regulator. In the event of freezing, you won't have to worry about having a hose blow (or the valve on your suit explode).
=======

The analogy to the "refrigerator effect" is slightly off the bull's eye, but does convey the idea.

By definition if you are diving the water must be above the freezing point - otherwise it would be a block of ice and you couldn't swim in it!

Not so, if kept moving, both fresh & salt water can get down to 28°f. (been there)
Even the best of "freeze proof" regs can have trouble in those conditions.

 

[Genesis]

but that's typically only at the surface....

The reasons for this are somewhat complex, but center around the fact that water which freezes into ice becomes buoyant and thus floats to the top, leaving the non-frozen water underneath.

 

[crispos]

Great thread, people. Free flow regs are a killer problem here in Ontario IMHO. Genesis, Bob3 and jetwrench, thanks for enlightening me on my SP G500/MK20 which I have learned by experience to be highly prone to free flowing. Reducing the IP is also a way to reduce FF risk, I heard.

Four out of 10 divers on a boat dive on the "Arabia" our famous killer wreck, free-flowed on June 29. One of them ditched his belt and did a buoyant ascent from 100 feet. I saw him go by, thought he was doing a CESA?! The only saving grace for FF"s seems to be they happen at the beginning of the dive, otherwise the fatality rate would be even higher...

My G500.Mk20 free flowed while I was helping another diver FF'ing on the 17 fathom wreck last summer (Long Point, Lake Erie). I had a dual reg valve so shut it down. But I still had to deal with a messy situation.

In my mind, boat captains/DM's must start including FF'ing risks into their briefings and prohibit some divers from going on to certain wrecks with certain regs and also size of tank. Yeah, I know, lost income, but less fatalities and injuries too!!!

 

[DA Aquamaster]

Jet Wrench - not breathing off your reg unitl you, the first and second strages are all under is a very good idea as it prevents the reg from getting excdessively cool before it eaven reaches the water.

We do a new years day dive here and you often see divers testing their regs, inflating BC's etc on the beach and then they freeze up in the first 2 minutes of the dive. It's a case of an otherwise good practice being totally inappropriate for the specific situation.

crispos - lowering IP will make a reg less susceptible to freeze up as it in effect reduces the flow rate of the reg. Flow rate is essentially the volume of air that can pass through the reg at a given time and if you reduce the IP, you reduce the volume of air in the reg at any one time and consequently the flow rate. There is obviously a point of diminishing returns in terms of flow volume and performance so 120 psi is about as low as you want to go in most regs.

Genesis is I think talking about the anomolous expansion of water. Water contracts and becomes denser as it cools down to 35 degrees. At that point it begins t expand with the result that water belwo 35 degree a lake or ocean rises to the surface where it then freezes. The ice on the surface then acts as an insulator and reduces the amount of additinal freezing that occurs.

If this did not happen, ice would form at the bottom of bodies of water and be insulated through the summer by the still cold overlying water. In a relatively short time every lake and ocean on the planet would be solid ice except for a few feet on the surface that may thaw during very cold summers.

This expansion of water also causes lakes to "turn over" twice a year which help oxygenate the deeper areas of most lakes.

But I digress....the point is in a near freezing body of water (less than 35 degrees) the coldest water is always at the surface.

 

[DeepScuba]

............prohibit some divers from going on to certain wrecks with certain regs .......


Uhmmm, we're off the deep end a bit now!

:cold:

 

[crispos]

I don't think so, Deepscuba. Sorry. I've seen alot of **** on boat dives.

 

[Juls64]

Jetwrench once bubbled...
I don't have the expert knowledge that others on this board have, but I have learned a tip on how to avoid freeflows from our local ice divers.
The local practice is not to breathe from the second stage until you begin the descent(ie:underwater), and do not allow the second stage to get wet before that time. Jetwrench

Mine started free flowing during the dive.

I took it to the LDS tonight. We looked it over together, they put it on the bench, it seemed fine. They tuned it down a little and suggested when I'm going where its cold, I might turn the VIVA adjuster down too.

Thanks for all the comments and discussion. This has been a very educational thread for me!

Julie

 

[Genesis]

won't do a thing for a first-stage freeze.....

 

[Juls64]

wouldn't my octo free flow too?