Cold water regs

[audission]

What differentiates a suitable cold water reg from a warm water one?

Is a cold water reg equally at home in warm waters?

 

[DA Aquamaster]

Cold water regs do fine in warm water.

Cold water first stages are either sealed or have heat transfer and/or ice prevention systems to keep them from freezing up due to the effects of adibatic cooling.

Basically as the air in the tank goes from 3000 psi to ambient pressure, the molecules get farther apart and have to speed up to maintain the new increased volume. They obtain that energy in the form of heat energy drawn from the surrounding environment which means the regulator itself. The regulator in turn has to draw an equal amount of heat from the surrounding water and if it does not keep up, the reg's surface falls below freezing and water then freezes to it as ice (which then acts as an insulator and aggravates the problem.) If the ice forms in an area that prevents the piston or diaphragm from returing to the closed position, the reg then uncontollably freeflows (which releases lots of air, which then really chills the regulator and guarentees it will remain frozen open.)

The same thing happens in the second stage where the air drops about 140 psi from the intermediate pressure to ambient pressure, drawing heat from the second stage. This can result in the valve in the second stage getting very cold and allows any moisture to freeze on it. If the ice prevents the valve from closing, it will cause a freeflow. If the ice forms on the lever however, it can prevent the valve from opening preventing you from getting any air at all.

So...cold water first stages are either sealed or very efficient at heat transfer with the surrounding water. Similarly, cold water second stages are either very good at heat transfer with the surrounding water or incorporate heat exchangers to use the warmth of exhaled air to return heat to the second stage.

 

[Tomikp]

... and don't forget to fill your tank with quality dried air. In case the air is moist, nothing will help you.

 

[vicdiver656]

Yes, most cold water regs are equally as efficient in warm water. I think the main difference is that the cold water regs are closed body diaphragms, while the warm water regs are piston-style. That was for first stages. I think that the only difference between the second stages is more air-flow and volume. For example, I have 2 SP G250Vs that are almost the same as the S600. The only difference is that the G250Vs have more air volume and flow. Making them better for cold water at depth.

I am a newbie, but I hope that helps,
Taylor
Vicdiver656

 

[h90]

one difference is that most cold water regulator are more metal than the plastic warm water.
So they are often more heavy. That may disturb some people.

 

[spectrum]

So...cold water first stages are either sealed or very efficient at heat transfer with the surrounding water. Similarly, cold water second stages are either very good at heat transfer with the surrounding water or incorporate heat exchangers to use the warmth of exhaled air to return heat to the second stage.

A very common example is the Sherwood Blizzard model.

Using Sherwoods dry bleed system the piston first stage remains dry internally and is "warmed" by the surrounding water.

For the second stage they start with a Oasis model regulator which has moisture capturing fins in the second stage that help recycle some of the divers exhaled moisture. They turn this on it's head by plating the fins to resist ice buildup making the fins into a heat sink and also plate the the diapgram lever to rsist sticking. They add some heat sink rings to the second stage inlet fitting and omit the hose protector so the heat sink can be "warmed" by the surrounding water. None of this degrades the perfomance of what is already a popular warm water regulator.

Older metal second stages come by a lot of these properties inherently.

Remember that the term warm is relative to the ice that can be formed my expanding air compared to the water you are diving in.

 

[anzac65]

Cold water regs do fine in warm water.

Cold water first stages are either sealed or have heat transfer and/or ice prevention systems to keep them from freezing up due to the effects of adibatic cooling.

Basically as the air in the tank goes from 3000 psi to ambient pressure, the molecules get farther apart and have to speed up to maintain the new increased volume. They obtain that energy in the form of heat energy drawn from the surrounding environment which means the regulator itself. The regulator in turn has to draw an equal amount of heat from the surrounding water and if it does not keep up, the reg's surface falls below freezing and water then freezes to it as ice (which then acts as an insulator and aggravates the problem.) If the ice forms in an area that prevents the piston or diaphragm from returing to the closed position, the reg then uncontollably freeflows (which releases lots of air, which then really chills the regulator and guarentees it will remain frozen open.)

The same thing happens in the second stage where the air drops about 140 psi from the intermediate pressure to ambient pressure, drawing heat from the second stage. This can result in the valve in the second stage getting very cold and allows any moisture to freeze on it. If the ice prevents the valve from closing, it will cause a freeflow. If the ice forms on the lever however, it can prevent the valve from opening preventing you from getting any air at all.

So...cold water first stages are either sealed or very efficient at heat transfer with the surrounding water. Similarly, cold water second stages are either very good at heat transfer with the surrounding water or incorporate heat exchangers to use the warmth of exhaled air to return heat to the second stage.

Very nicely put DA.

 

[Thalassamania]

The only thing I'd like to add is the often a "cold-water" version will marginally underperform when compared to the same model "warm-water" version. THe difference is often so small that you'll never notice it, but you may see it in a spec. sheet.