regulator icing

[Dryglove]

Im currently stationed in the north eastern part of oregon with the army reserves due to the sept 11 acts.I figured while i was here i would try some of the fresh water diving here.I went diving in the columbia river near the richland bridges at clombia point. Being from CA i dove mostly in the ocean around monterey and morro bay.

Heres my problem about 10 min into my dive my reg starts to very slowly free flow.I just ignored it and kept an eye on my pressure.It started to slowly get worse.I switched over to my pony and took a look at my primary reg.I look down the mouth piece and its full of white stuff(took me a second to figure out it was ice).So i try breathing off it again and it goes into a full fledged free flow.So i use the pony again and call off the dive and surface.

Once on the surface i see the first stage is completely iced over and my second stage is full of ice inside the mouthpiece. Being from ca and diving in the ocean i have never experienced this before.Im not sure what the temp of the river was.I do know it was friggin cold.My hands got extremely cold before i donned my gloves.I was dressed in my drysuit and undergarment and was nice and toasty except for my hands which was tolerable once i donned my seasoft gloves.

Heres my question.I use a scubapro mk20 and s550 set up.What caused my reg too freeze.Was it just due to the temp of the water or maybe inproper breathing.My deepest depth was only 20ft.Also at what temp will a reg start to freeze up and is there anyway to prevent it.If any of you locals know the temp of the water here let me know.It is much colder than monterey for sure.

 

[buff]

Most freeze up occur at the second stage since that is where the most water vapor or just water is at.

Ways to avoid "Mr. Freeze"

If you place the reg. in your mouth don't take it out prior to diving. Taking the reg. out of your mouth will allow the water vapor from you breath to build up ice crystals in it.

Bobbin up and down in the water resulting in your reg. coming in and out of the water. Bob3 can tell you from experience that this is bad news. Again, you are allowing the diving water and your expelled water vapor to build up ice on the reg. as it is exposed to air.

Don't get your reg. wet prior to diving and if you do put it in the water don't take it out until you are done diving.

Avoid big purges of your reg. prior to diving. When you purge your reg. the gases expand and absorb heat from the surrounding environment. The cooling of the reg. can result in any water vapor in it to freeze.

Since scuba results in the expansion of gases and their resulting cooling you don't have to dive in 32 degree water to have a freeze up.

If the air in your tank is moist(it shouldn't be if it was filled properly-cotton mouth is a blessing in cold water diving.) then you can get a second stage freeze AND a first stage freeze due to no fault of your own.

(Buy a Poseidon Odin or Cyclon. I had to get that one in.)

Cold water diving just requires a little more thought and awareness than diving in the tropical waters of Monterey.

 

[Lost Yooper]

We have a lot of MK20's freeze up here. Here's what you have to do:

Get the first stage sealed up with silicon -- "winterize" it.

Reduce the IP to 130 or so.

Don't breath on it until you are submerged.

Keep the reg warm prior to getting into the water.

Don't purge it while diving.

The two biggies are the sealing and reducing the IP.

Good luck.

Mike

 

[jbd]

Lost Yooper--can you describe the winterizing process? I'll be going back to the place where the water is in the upper 30's. I've never had a freeze up or icing problem but have wondered if there is a substantial risk and what to do to prevent it.

A question for any northern divers--is regulator freeze or icing a problem for cold weather diving only?

 

[Lost Yooper]

One of the Scuba Pro techs here can do a better job of describing the process than I can. I'll hand that one to them since I don't use Scuba Pro regs. The last I heard, Scuba Pro also had a a few pistons available designed for cold water too, but again, I'll defer to others on that.

Yeah, basically reg freezing is a cold water divers problem, however the cooling effect of air is.... well... pretty cool . Here's some tidbits:

With a tank in 75F water at 3000psi, the air coming out of the first stage will be about 25F.

At 40F, the air coming out of the first stage is about -10F (at 3000psi tank pressure).

At 32F, it's about -18F.

So, that's why unsealed first stages freeze up. The super cold air hits the water in the first stage and freezes the guts of the first stage. A sealed first stage can freeze up too if there any moisture in the air tank.

Mike

I use Apeks and avoid one whole part of the freezing equation -- first stage freeze up. The rest is up to me -- reducing the IP and breathing technique.

 

[buff]

Reducing interstage pressure will have negligible effect on freezing in a reg. since you can only reduce the pressure gradient a few mmHg.(20-40mmHg) before you get a poor breathing reg.
Using the Ideal Gas Law, PV=nRT, it is apparent that a minimal change in interstage pressure will result in a minimal change in temp.-you get a proportional change as you drop the interstage pressure. And since you have decreased the I.P. only a relatively small amount you get only a relatively small amount of adiabatic expansion-and hence cooling effect. The largest pressure gradient drop and therefore the greatest cooling effect, takes place between the first stage and the interstage pressure. This is why ice forms on a regs first stage so quickly.

Most freezing happens at the second stage and is primarily a result of exposure to cold after becoming wet, with either expelled water vapor from the diver or immersion in water prior to diving-just like the Apeks technician has described in other threads.

 

[Lost Yooper]

I've had my Zeagle freeze up several times, when I first got it, in 35F water. The IP was factory set at 145psi. I reduced it to 130psi and never had a problem again. All of my Apeks are set at 130psi for ice diving, and I've never had a problem with them. Lowering the IP is highly recommended for cold water diving. If you crank them up, they are more prone to free flow.

You have to slow that air down.

Mike

 

[Rick Murchison]

Before LY & buff get into an argument over nits, you're both right. The reduction of IP has a small effect on adiabatic cooling at the second stage, and it is often enough to obviate the freezing problem. Physics is physics.
Rick

 

[Lost Yooper]

Bingo Rick. Combine that with the warming of the air while in the hose, and it really helps. Breathing on a long hose helps too as the air has longer to warm up a bit. Any cold water diver/tech will tell you to seal the first stage, reduce the IP, and use proper breathing techniques to cure freeze ups (for the most part). You also should have an air source with a dew point less than -50F.



Mike

PS. A buddy of mine just had his Odin freeze up this past weekend .

 

[Rick Murchison]

Originally posted by Lost Yooper
Breathing on a long hose helps too as the air has longer to warm up a bit.

HHHhhhaarrr!
I love it - hadn't thought of that reason to use a long hose - but you are correct!
Rick