HatchetJoe
Contributor
I'm sorry to hear about your experiences, i find it unusual. I dive an upgraded Mk20 w G500 all around including some under the Ice dives here in New England, must be my luck but they have been bulletproof so far.
ScubaPro.... Should I be done with them??
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Greg Barlow
Contributor
As with DA Aquamaster, I believe that the majority of free flows are due to diver habits.
That said, I have now been diving for 33+ years, and have yet to experience a free flow. I would estimate that at least 400 of my logged dives have been in water that was 50 degrees or colder, and at least a third of those in water 40 degrees or colder.
As far as my own cold water regs go, I have had tremendous luck with Mares metal second stages. My current favorite is the V42 Proton Metal. The diaphragm first stage can be fitted with the dry cold water system, and the thermal conduction of a metal second stage goes a long way in the prevention of ice formation.
I own a few balanced piston first stages, but don't use them in water below 60 degrees.
Interestingly, free flows were a rarity back in the days when I began diving. Of course, at that time first stages did not have the flow rates that many of today's balanced piston models generate. Also, the large, metal second stages effectively used the ambient water's heat to warm the incoming air. As the first stage flows, adiabatic pressure causes the gas to lose heat. It is not uncommon for the outgoing gas to be at least 40 degrees below that of the surrounding water. When you dive in water that is already close to freezing, that can cause some real problems. When the gas expands again in the second stage, it becomes even colder. Metal conducts heat much, much more effectively than polymer (plastic). This is the reason why a plastic spoon left in hot liquid doesn't get excessively hot in a short period of time.
As far as the ScubaPro MK17 goes, I would predict that the problem is in the second stage. The MK17 has a maximum flow rate of around 170cfm, and the moving parts are pretty well isolated from the coldest areas of the reg's body.
Greg Barlow
That said, I have now been diving for 33+ years, and have yet to experience a free flow. I would estimate that at least 400 of my logged dives have been in water that was 50 degrees or colder, and at least a third of those in water 40 degrees or colder.
As far as my own cold water regs go, I have had tremendous luck with Mares metal second stages. My current favorite is the V42 Proton Metal. The diaphragm first stage can be fitted with the dry cold water system, and the thermal conduction of a metal second stage goes a long way in the prevention of ice formation.
I own a few balanced piston first stages, but don't use them in water below 60 degrees.
Interestingly, free flows were a rarity back in the days when I began diving. Of course, at that time first stages did not have the flow rates that many of today's balanced piston models generate. Also, the large, metal second stages effectively used the ambient water's heat to warm the incoming air. As the first stage flows, adiabatic pressure causes the gas to lose heat. It is not uncommon for the outgoing gas to be at least 40 degrees below that of the surrounding water. When you dive in water that is already close to freezing, that can cause some real problems. When the gas expands again in the second stage, it becomes even colder. Metal conducts heat much, much more effectively than polymer (plastic). This is the reason why a plastic spoon left in hot liquid doesn't get excessively hot in a short period of time.
As far as the ScubaPro MK17 goes, I would predict that the problem is in the second stage. The MK17 has a maximum flow rate of around 170cfm, and the moving parts are pretty well isolated from the coldest areas of the reg's body.
Greg Barlow
Pearldiver07
Contributor
I might note that the other thing that appears to be in common with all of these regs is that you've gotten them through the same shop?
Could it be that something that they're doing during tuning and set up that might be putting the cracking pressure too low?
Just tossing this out. I've dived Mk20/25 for years, and haven't had a free flow. Although I do admit that I've swapped out the second stage to use an old 250 instead.
Anyway...
OP
cobaltblue
Contributor
The thing that puzzles me about all this is that I get bashed for having top dollar equipment free flow. The other thing I've noticed is that SP divers are the only ones that ever talk about free flows.
DA, I have NOT made up my mind as I would really like to find a solution to this that isn't going to cost me thousands of dollars. My mind is made up in the fact that I will no longer dive regs that free flow. Congrats on all your diving, I'm not that old. I also know that I'm not the only one here in the Great Lakes that has their SP regs free flow so let's take my poor diving skills out of the picture. I can't count on one hand anymore the amount of free flows I've had in the last 12 months. Even if 95% of them are my poor diving, the other 5% is unacceptable. I respect the amount of knowledge you have with SP and other diving stuff but it can't just be me. There has to be a reason they call SP in the Straits "ScubaFlow".
The facts are this: The regs have been purchased at the same shop but have been rebuilt by different techs at different shops. The regs have frozen on both my wife and I with the exception of her MK17. The last one was about 3 minutes into the dive. We slowly descended, we usually drop slow as my wife is a little slow to clear, I last inflated my BC at about 75' and added air to my DS at about 85', the reg froze at about 90' and at that time I had no choice but to add air to my BC. I may have added air to my BC before the freeze but once again I will stress that I'm not going to hold my breath, rest on the bottom and alternate between breathing and inflating to keep my reg from freezing, that's not acceptable. A side note, since I've gotten too used to this, I make it a habit not to inflate too long or breath and inflate, if possible, to try to keep this from happening.
I guess the one factor that may not be the same with all of this is that where it happened was very clean, fresh water.
Anyway, I thank everyone and respect your opinions but I find it fascinating that brand loyalty will cause people to look at factors other than the brand they use and like. I'm not saying that SP isn't a quality product, I'm just wondering if it is not suited to the diving I do or maybe it's just the fact that I'm a terrible diver and I'm lucky to get back to the boat after every dive. It's either that or I'm just trying to get my freeflow card wrapped up.
DA, I have NOT made up my mind as I would really like to find a solution to this that isn't going to cost me thousands of dollars. My mind is made up in the fact that I will no longer dive regs that free flow. Congrats on all your diving, I'm not that old. I also know that I'm not the only one here in the Great Lakes that has their SP regs free flow so let's take my poor diving skills out of the picture. I can't count on one hand anymore the amount of free flows I've had in the last 12 months. Even if 95% of them are my poor diving, the other 5% is unacceptable. I respect the amount of knowledge you have with SP and other diving stuff but it can't just be me. There has to be a reason they call SP in the Straits "ScubaFlow".
The facts are this: The regs have been purchased at the same shop but have been rebuilt by different techs at different shops. The regs have frozen on both my wife and I with the exception of her MK17. The last one was about 3 minutes into the dive. We slowly descended, we usually drop slow as my wife is a little slow to clear, I last inflated my BC at about 75' and added air to my DS at about 85', the reg froze at about 90' and at that time I had no choice but to add air to my BC. I may have added air to my BC before the freeze but once again I will stress that I'm not going to hold my breath, rest on the bottom and alternate between breathing and inflating to keep my reg from freezing, that's not acceptable. A side note, since I've gotten too used to this, I make it a habit not to inflate too long or breath and inflate, if possible, to try to keep this from happening.
I guess the one factor that may not be the same with all of this is that where it happened was very clean, fresh water.
Anyway, I thank everyone and respect your opinions but I find it fascinating that brand loyalty will cause people to look at factors other than the brand they use and like. I'm not saying that SP isn't a quality product, I'm just wondering if it is not suited to the diving I do or maybe it's just the fact that I'm a terrible diver and I'm lucky to get back to the boat after every dive. It's either that or I'm just trying to get my freeflow card wrapped up.
woodsandwatertoo
Contributor
Sherwood Blizzard would be a good try. Specifically built for Cold Water Diving.
I agree that technique can prevent/overcome most free-flow problems but the best solution isn't technique, its technology.
By way of example: most of us understand that avoiding pre-breathing a regulator in cold conditions will help reduce freeze-ups - a technique that will help prevent the problem. Skipping important steps in the pre-dive safety check is it's own kind of bad technique, however.
Only rarely is adapting your behavior the best choice; most humans just aren't that good at it. Almost always (and certainly in the instance of cold-water diving) a better choice is to find an appropriate tool for the conditions.
There are a lot of things that divers can do to avoid a frozen regulator. The place to start is by using a regulator that can handle the conditions.
By way of example: most of us understand that avoiding pre-breathing a regulator in cold conditions will help reduce freeze-ups - a technique that will help prevent the problem. Skipping important steps in the pre-dive safety check is it's own kind of bad technique, however.
Only rarely is adapting your behavior the best choice; most humans just aren't that good at it. Almost always (and certainly in the instance of cold-water diving) a better choice is to find an appropriate tool for the conditions.
There are a lot of things that divers can do to avoid a frozen regulator. The place to start is by using a regulator that can handle the conditions.
I would look at an environmentally-sealed balanced diaphragm reg if I dove in cold water. The coldest water I've been in is 42F and that's quite cold enough. I have an older Apeks Zeagle 50D that is sealed and it's never given me a moment's trouble.
Hmmmm...maybe you can use this problem as an excuse to move down South where the weather is warm and the water is clear--and salty.
Hmmmm...maybe you can use this problem as an excuse to move down South where the weather is warm and the water is clear--and salty.
Well... that turns out not to be the case. There are lots of posts on SB about non-SP regs free-flowing. I have posted in the past about an Atomic M1 free-flow problem I had.
I own Apeks, Atomic, OMS and Scubapro regs. The 25/650 gets a lot of bad press, though, but it's not the reg's fault. It's the fault of the LDS who sell you the wrong reg for the environment you're diving. Assuming a diver doesn't know better and is trusting the LDS to sell you the correct product, why do so many LDS's peddle 25/650 to cold freshwater divers? It's gotta' be the profit, I guess. The 25/650 is an excellent reg for drift diving Palancar reef in Cozumel, but I wouldn't take it in the Great Lakes.
I use a 17/250 for my O2 deco bottle in cold water. Of course, it never free-flows because it's the right tool for the job.
Again, I don't blame SP for free-flowing 25's, I blame the diver or LDS for trying to make the wrong tool do the wrong job.
Marcin2005
Contributor
"cobaltblue" I'd be willing to take that overpriced Scubapro paper weight of your hands for a nominal amount 
BTW I just switched from Mares Abyss to MK17/G250V combo. So far no issues in a 45 degree water.
BTW I just switched from Mares Abyss to MK17/G250V combo. So far no issues in a 45 degree water.
halocline
Contributor
There is absolutely no reason that I can think of that the MK17 would be any more prone to free flows in cold water than any other environmentally sealed diaphragm 1st. Which is to say, it's designed like any other cold water reg specifically to resist freezing. If you want to try an inexpensive experiment, and you believe in the techs that work on your gear, I suggest you get a metal case SP 109 2nd stage and have your tech upgrade it to balanced/adjustable with the G250 poppet and spring. The whole thing including rebuild should be under $50. Pair that with your MK17 and see what happens; when you can't get it to freeflow, you can write SP a nice letter saying that you solved your problem with their regs by buying one that's 30 years old.
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