MichelG
Registered
I used a Mk 17/G250v in 37F waters a few times without an issue. Up here in Montreal a lot of divers use this combination for ice diving. I heard from my LDS owner that Mk17/ A700 is better because the A700 is all metal.
Tech and Ice Diving - Scubapro, Poseidon, Hog, Apeks?
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Several thoughts....
1. The Mk 17 is sealed and has been tested at 165' of 35 degree f water at high flow rates for 200 min without freeze flowing. It should not be the problem. I have serviced hundreds of them over the years since they were introduced and I have yet to find one where the ambient chamber was flooded due to a leaking outer seal, but nay thing is possible. it may be worth checking to ensure it is still dry.
2. The gas is often over looked in freeze flow events, but no amount of sealing will prevent a free flow if the gas is overly wet and is casuing ice to form inside the first stage (which is very very cold, due to adibatic cooling). So ensure the gas is not overly wet due to a failed separator on the compressor, water in a tank, etc.
3. The Mk 25 is known for freeze flows in water below 45 degrees. Loyal users with long experience with it in very cold water will disagree, but even Scubapro admits this. It can work in water colder than 45 degrres F but you need perfect cold water technique. For deep, very cold water technical diving I used late production Mk 20s with the late Mk 15/early Mk 20 SPEC boot installed as the Mk 20/25 TIS system just does not provide much margin for error in cold water especially at depth where flow rates are high. And when the Mk 17 was introduced, I jumped on it, never looked back and have never regretted it.
If cold water diving is what you do, dump the Mk 25 and go with the Mk 17.
4. The S600 is also known to have isuses with freeflow in cold water. It starts out as a slight freeflow, and if attached to a Mk 25, it will often precipitate a full on first stage freeze flow. Scubapro is introducing a metal air barrel in the S600 and that will probably help, but I don't recommend the older S600 in very cold water.
5. I have never had issues with a G250 or a G250V in ice diving conditions. Both have a metal air barrel with a metal knob on one end and a metal inlet fitting nut on the other end, so heat transfer is quite good.
6. The R380/390/295/290/190 are not overly reliable in very cold water as heat transfer is limited. The big killers of those models is water entering the second stage during a dive. If the second stage intenrals stay dry, it will do fine for the entire dive. however, if the reg falls out of your mouth during the dive, the resulting rush of gas (and concurrent adibatic cooling of the aspirator) will often prompt a freeze flow as water freezes on the aspirator and prevents the poppet from reseating properly. Even without the free flow, just getting water in the reg, and then into the aspirator body can casue a freeze flow shortly after wards.
7. The A700 should theoretically be pretty reliable in cold water due to the metal case and high heat transfer potential. However I have no direct experience with it in extremely cold water.
1. The Mk 17 is sealed and has been tested at 165' of 35 degree f water at high flow rates for 200 min without freeze flowing. It should not be the problem. I have serviced hundreds of them over the years since they were introduced and I have yet to find one where the ambient chamber was flooded due to a leaking outer seal, but nay thing is possible. it may be worth checking to ensure it is still dry.
2. The gas is often over looked in freeze flow events, but no amount of sealing will prevent a free flow if the gas is overly wet and is casuing ice to form inside the first stage (which is very very cold, due to adibatic cooling). So ensure the gas is not overly wet due to a failed separator on the compressor, water in a tank, etc.
3. The Mk 25 is known for freeze flows in water below 45 degrees. Loyal users with long experience with it in very cold water will disagree, but even Scubapro admits this. It can work in water colder than 45 degrres F but you need perfect cold water technique. For deep, very cold water technical diving I used late production Mk 20s with the late Mk 15/early Mk 20 SPEC boot installed as the Mk 20/25 TIS system just does not provide much margin for error in cold water especially at depth where flow rates are high. And when the Mk 17 was introduced, I jumped on it, never looked back and have never regretted it.
If cold water diving is what you do, dump the Mk 25 and go with the Mk 17.
4. The S600 is also known to have isuses with freeflow in cold water. It starts out as a slight freeflow, and if attached to a Mk 25, it will often precipitate a full on first stage freeze flow. Scubapro is introducing a metal air barrel in the S600 and that will probably help, but I don't recommend the older S600 in very cold water.
5. I have never had issues with a G250 or a G250V in ice diving conditions. Both have a metal air barrel with a metal knob on one end and a metal inlet fitting nut on the other end, so heat transfer is quite good.
6. The R380/390/295/290/190 are not overly reliable in very cold water as heat transfer is limited. The big killers of those models is water entering the second stage during a dive. If the second stage intenrals stay dry, it will do fine for the entire dive. however, if the reg falls out of your mouth during the dive, the resulting rush of gas (and concurrent adibatic cooling of the aspirator) will often prompt a freeze flow as water freezes on the aspirator and prevents the poppet from reseating properly. Even without the free flow, just getting water in the reg, and then into the aspirator body can casue a freeze flow shortly after wards.
7. The A700 should theoretically be pretty reliable in cold water due to the metal case and high heat transfer potential. However I have no direct experience with it in extremely cold water.
DA - what about a MK-17 with a 109? I have pondered this combination as I have access to each (and I know it would drive some folks I dive with nuts!).
tadawson
Contributor
Ouch! Here in Texas, the shop I used charges a flat $49 labor for reg/octo/spg plus parts, and the last time I had my Cyklons done, the kits came in at about $50 or so all told, so I ended up out about $100 for the whole setup. That labor charge, by the way, is the same for any reg they work on (and I am not aware of any they won't work on) - the only difference is the price of parts.
Nothing personal, but at $200, sucks to be you . . . .
- Tim
halocline
Contributor
This was meant for DA, but I have a feeling that he'll agree that the old 109 (or balanced adjustable) would be a fantastic cold water reg. If someone is uncomfortable trusting a reg that can be easily bought for $50 on ebay, he could get a fully re-chromed restored one from Couv on this forum at a considerably higher price.
I've seen them and they are beautiful. SP did such a nice job re-issuing the G250V, it kind of makes me wish they had done something similar with the balanced/adjustable instead of the A700.
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If I was buying new, HOG without a doubt.
ajduplessis
Contributor
Keep the Mk17 and add the G250V
I'm in Iceland as well.
The HOGS held up well at 30 meters around 2° celsius in Silfra recently.
Haven't had much experience with them diving deep but my dive buddies Apeks regs seem alot more prone to freeflow.
If you want to give them a try you're welcome to borrow them for a day
The HOGS held up well at 30 meters around 2° celsius in Silfra recently.
Haven't had much experience with them diving deep but my dive buddies Apeks regs seem alot more prone to freeflow.
If you want to give them a try you're welcome to borrow them for a day
CPH
Contributor
I have seven sets of Mk25's between me and the missus with my set having the A700 and S555 and the missus has GV250's.
We are ice divers and experiance no problems.
Maybe it does have something to do with the way you breath. We are both very relaxed breathers and have never experianced problems under ice.
We are ice divers and experiance no problems.
Maybe it does have something to do with the way you breath. We are both very relaxed breathers and have never experianced problems under ice.
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