IP for Ice Diving

I've gotten interested in taking an ice diving class this winter and have started researching various aspects of it. One thing I ran across was the recommendation from a reg manuf. (not Sherwood), to ensure that the IP was set LOW... near the 125psi range.

As the reg I intend to use on the pony bottle will be the Sherwood Blizzard (due to the good reputation it seems to have for this application), I'd like to have actual "technical" validity of whether or not this IP issue has any validity I understand the basic theory behind it... but also realize that many things that are theoretically true have little practical value.

... figured it's time to seek the input of the experts...

Thanks

Personally I dont really see the need for it. I do all my ice and cold water dives with the IP on my Zeagles set at the recommended 145. Considering that the tank pressure could be as high as 3500 psi, having your IP set at 125 versus 145 doesn't really make a big difference as far as a percentage drop.

Jimmer:

Personally I dont really see the need for it. I do all my ice and cold water dives with the IP on my Zeagles set at the recommended 145. Considering that the tank pressure could be as high as 3500 psi, having your IP set at 125 versus 145 doesn't really make a big difference as far as a percentage drop.

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But its the drop off from 125 (vs 145) to ambient is what the change is for. There is two drops of pressure. Tank->1st stage and 1st stage->2nd Stage. With the IP change on side gets "worse" and the other side "better".

In practice I am not sure how much effect it has. I know I did it to my regs. YMMV.

Two views so far. Ummm... Sherwood rep???

J.R.:

I've gotten interested in taking an ice diving class this winter and have started researching various aspects of it. One thing I ran across was the recommendation from a reg manuf. (not Sherwood), to ensure that the IP was set LOW... near the 125psi range.

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Cold water freeflows are caused by ice forming inside the first stage, which is caused by the pressure drop from the Tank Pressure to IP, which chills the first stage, forming ice, which holds the first stage open and increases the IP past the point where the second stage can hold it back.

Lowering the IP will do nothing to stop this, but will move the IP outside the range the second stage was designed for. I can't see any possible advantage to doing this.

If you'll be ice diving, you should be using a reg designed for extreme cold water, and not try to tweak something that isn't (especially with a tweak that won't fix the problem). According to it's specs, the Blizzard should be fine without modifications, although I've never actually used one.

Terry

There are two types of freezing that can occur. 1st stage freeze and 2nd stage freeze.

An adjustment in IP on the first stage is not reccomended by Sherwood. The Sherwood Blizzard first stage is an environmentally sealed 1st stage which essentially eliminates the 1st stage freezing. The Blizzard 2nd stage has several features (heat retention fins and teflon coated parts) that are designed to reduce the freezing in the second stage.

Does this answer your questions?

Sherwood SCUBA rep.:

There are two types of freezing that can occur. 1st stage freeze and 2nd stage freeze.

An adjustment in IP on the first stage is not reccomended by Sherwood. The Sherwood Blizzard first stage is an environmentally sealed 1st stage which essentially eliminates the 1st stage freezing. The Blizzard 2nd stage has several features (heat retention fins and teflon coated parts) that are designed to reduce the freezing in the second stage.

Does this answer your questions?

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Yep... if the manuf. doesn't recommend it I accept that as as close to gospel as it comes... thanks for the response.