Scubapro regulators under Ice

[DA Aquamaster]

Quick history lesson, the big manufacturers tend to focus on either piston or diaphragm style first stages. Apeks and Poseidon are the big boys in the Diaphragm side, neither of them make a piston first stage, Scubapro and now Atomic *bunch of ex Scubapro engineers btw* are basically all pistons. Scubapro does make the MK11, and MK17 which are diaphragm *I think these are actually a Tusa design that was adopted by SP*, but you don't see them often, the MK25 and MK2 are much more common and generally the ones you see when people think of Scubapro first stages.

Diaphragm regulators are generally preferred to piston regulators in ice diving conditions mainly due to their ability to be sealed much more easily. Poseidon dominates this field with Apeks almost tied for 2nd. Apeks is probably more popular, but more of the cold water Navy's turn to Poseidon.
The MK17 is a diaphragm regulator that is sealed, so shouldn't have any cold water issues there, the MK25 can be sealed, but it involves packing the housing with grease, and it has had a lot of issues with cold water performance over it's lifetime. I would steer clear of pistons for any cold water diving, not that they can't be used or aren't being used, but there are much better designs out there for cold water. Hog D1/D3, Apeks full series, Poseidons with the environmental caps on them, hell even without them the Poseidons generally have less freezing problems than the piston designs, Dive Rite, etc. Any sealed diaphragm will out perform a piston in cold water.

Scubapro second stages are a non-issue, the designs of the seconds are all pretty much the same aside from the servo assisted regs from Poseidon and Oceanic/Hollis, so it is all about the first stage design.

A couple corrections are in order.

Scubapro sold the Mk 14 for awhile which was a non-scubapro designed regulator to fill a perceived gap for a diaphragm first stage until Scubapro completed the design of the Mk 16. The MK 16 is a totally Scubapro designed regulator. Scubaro however farms out production of their regulators to Tabata, and Tabata has first rate manufacturing facilities, so it makes sense to do that. Under the agreement however, Tabata was allowed to market the Mk 16 with some cosmetic changes as a TUSA regulator. (TUSA = Tabata USA.)

The Mk 17 was a refinement of the Mk 16 to include a new longer lasting seat design, a larger working range, and a sealed ambient chamber. Halcyon sells this same Mk 17 first stage (as well as the Mk 25) under a similar agreement with a modified trim package to make them look cosmetically a little different.

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In practice, the old Mk 5, Mk 10, Mk 15 and very early Mk 20 first stages with the SPEC (Silicone Protected Environmental Chamber) kits worked quite well under the ice, provided that you properly packed the environmental chamber to minimize voids in the silicone (something of a lost art now) and kept it topped off over the season (the SPEC boots helped but they were not perfect).

In contrast the later Mk 20 and all the Mk 25 first stages with their various and constantly upgraded cold water kits were quite freeze prone in sub 40 degree water. I used to to a great deal of ice diving and 35 degree deep great lakes wreck diving, and I went from using SPEC kitted MK 20s to Mk 17s based on dive buddies who had very unsatisfactory dives with the Mk 25. in 40'ish degree water with perfect cold water diving techniques the Mk 25 can be made to work, but it's marginal.

The sealed Mk 17 is a much better choice and it is essentially bullet proof under the ice. You can make it freeze up, but you have to free flow it to the point that you get a giant ice ball around the first stage that then covers the ambient chamber diaphragm and keeps depressed. Odds are you'll be out of gas by then anyway.

With that all said, the large ambient pressure holes in the Mk 16 allowed it to preform surprisingly well in very cold water, including ice diving, provided you used good technique and did not use the reg at all (including testing, inflating the BC, drysuit, etc) until the first stage was entirely submerged, and provided you broke up the usage in smaller bits, such as not inflating the BC, and dry suit while inhaling or at the same time, and not using a long blast on the inflator after you dropped like a Stuka to the bottom.

The Mk 2 with it's larger ambient pressure holes also worked pretty well, in part because the lower flow rate prevented some of the abuses that cause a freeze flow.

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In the distant past companies like Poseiden and US Divers used ambient chambers filled with alcohol (poseiden) or silicone oil. These were generally a major PITA and the oil would expand in warm weather, bulging the diaphragm which would eventually leak all over the rest of your dive gear, then let the first stage freeze up on you if you were lucky and if not the water in the ambient chamber would just corrode the internal bits.

Today most companies use air filled sealed ambient chambers. I most cases it's a fixed volume system sealed with a diaphragm, although Sherwood still uses an air bleed system, and another company uses a very complex system with a diaphragm operating a schraeder valve to let air in and a mushroom valve to let air out.

Dive Rite, Aqualung, and Aeries (among others) all make decent sealed first stage regulators that are fine for ice diving.

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Second stage design also makes a difference. The older Scubapro R108 (High Peformance) R109 (Adjustable) and R151 (Balanced Adjustable) second stages were superb under the ice as the all metal case, orifice and air barrel helped transfer heat from the surrounding water to the valve and lever, preventing it from freezing up.

When Scubapro started using a plastic case in the G200 (a plastic cased R109), G200B (a balanced plastic cased R109) and G250 (a plastic cased R151), it lost some of that heat transfer capability, but the G250 still had an air barrel that extended all the way through the case and between the metal barrel and nut on the inlet side, and the barrel and the all metal adjustment knob on the other side, they still had adequate heat transfer and were still quite reliable under the ice.

However, when they moved to the all plastic air barrels in the G250HP, and eventually the S600 they now had a regulator where the temperature of the valve would fall well below freezing due to inadequate heat transfer. The end result was that if you, for example, allowed the second stage to fall out of your mouth and allowed any water in the second stage, it would instantly freeze on the valve and lever and cause a freeze flow. So again, the work ok for ice diving, but they require special attention to ensure you don't get water in the regulator.

The short lived X650 had a few problems, but one of the minor ones was a tendency to breathe just a bit wet, which was nice in the tropics to prevent dry mouth, but on an ice dive it almost guaranteed a slow, steady free flow that would then further cool the system and result in a progressively larger free flow until it got totally out of control.

The D400 could be abused in a similar manner as if you swam inverted under the ice, small amount of water would come through the large exhaust valve and run into the top of the regulator and potentially cause freeze issues.

On short, for ice diving, I always preferred the old reliable Balanced Adjustable second stage. My advice to anyone contemplating serious cold water or ice diving, is to use an all metal second stage, or at least a second stage with an all metal air barrel with plenty of surface area exposed to the water to facilitate heat transfer.

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Now…if you are really serious about ice diving, do it right and get a double hose reg. In a double hose design both the first and second stages are sealed. Any water entering the second stage would have to find it's way upstream past a one way mushroom valve, and against the airflow in a long corrugated hose, then flood the can enough to reach the lever and valve. Even if it did, with the all metal design and the shear area of the metal cans, heat transfer is superb and the entree regulator will be close to the water temp, rather than well below freezing.

It's as freeze resistant as it gets and if you freeze one up, it's from moisture in the air in the tank, and a sight you need need higher quality air.

 

[tbone1004]

they are an unsealed piston design which means water can get inside the regulator and freeze. With all first stages the change in temperature from tank pressure to IP is quite drastic, in 40F ambient, the air on the other side of the first stages is about 2*F. If the water is allowed to cool that much that fast, the regulator will freeze. Generally only an issue if the water temperature is in the low 30's, i.e. ice diving, or you are breathing at the surface where the first stage gets wet and the cold air, generally below freezing, doesn't warm the first stage up enough to keep it from freezing. Spring freezes, air keeps coming. Real bad.

For diaphragm regulators, they put an environmental seal on them to keep all of the water out, for piston regulators, they pack the inside of it with grease to keep water from coming in. It attracts all sorts of nasty particles, and it's just generally unpleasant for the technicians servicing them. If you take them into really hot areas, i.e. Florida in the summer, if the bottles are sitting in the sun, the grease can actually start oozing out which is just nasty.

Unfortunately in the last 30 years, piston regulators really don't have much going for them for every day use over a diaphragm, and if you're diving in salt water, or cold water, or nasty murky water, sealed diaphragms are superior in every way. I do use a piston for O2, they handle high pressure O2 much better, but that's about all I would use one for.

 

[BoltSnap]

they are an unsealed piston design which means water can get inside the regulator and freeze. With all first stages the change in temperature from tank pressure to IP is quite drastic, in 40F ambient, the air on the other side of the first stages is about 2*F. If the water is allowed to cool that much that fast, the regulator will freeze. Generally only an issue if the water temperature is in the low 30's, i.e. ice diving, or you are breathing at the surface where the first stage gets wet and the cold air, generally below freezing, doesn't warm the first stage up enough to keep it from freezing. Spring freezes, air keeps coming. Real bad.

For diaphragm regulators, they put an environmental seal on them to keep all of the water out, for piston regulators, they pack the inside of it with grease to keep water from coming in. It attracts all sorts of nasty particles, and it's just generally unpleasant for the technicians servicing them. If you take them into really hot areas, i.e. Florida in the summer, if the bottles are sitting in the sun, the grease can actually start oozing out which is just nasty.

Unfortunately in the last 30 years, piston regulators really don't have much going for them for every day use over a diaphragm, and if you're diving in salt water, or cold water, or nasty murky water, sealed diaphragms are superior in every way. I do use a piston for O2, they handle high pressure O2 much better, but that's about all I would use one for.

Not sure of what/who you are responding to but if you are referring to the Atomic M1 regulator, you are wrong on all counts. Take a look at Atomic's website and visit their regulator page and learn the facts.

 

[tbone1004]

The Atomic M1 seals by filling up the holes with christolube then putting a ring around the holes to keep it from coming out. Costs quite a bit of money to seal the damn things too because of the amount of christolube involved. Atomic said about $40 per service to seal it. So no, not wrong, it is still sealed the same way the MK25 is, pack it with grease.

http://www.scubaboard.com/forums/atomic-aquatics/437648-question-atomic-stages.html
for reference, Atomic posted the answers regarding packing with grease and converting the first stage to being sealed. These are not like a diaphragm where you just put the cap on it and it keeps everything out. Pistons don't work like that.... If you pack them they work just fine in cold water, but you have to pack them every time you service them and O2 clean grease isn't cheap. I'd rather save the hundreds of dollars servicing them and just use a superior design for the application which is a sealed diaphragm. Pistons had their advantages, they flow a boat load of air, far more than any team of divers could ever use at once, they perform better with pure O2, which is why I still use them for that, but for every day diving, or diving in cold/murky/salt water, having a regulator that is completely sealed is just better.

If you have a piston that isn't sealed you have to soak and flush it to keep salt from building up around the springs, if it's sealed you have pay $40-$50 to get it repacked every time you service it. Nothing about that sounds appealing to me. I can take an Apeks DST, give it a quick rinse from a hose and everything is clean, no worry about salt building up because it can't get in anywhere but the surface, the inside of a piston if it isn't sealed is a salt trap. Poseidons don't have traditional environmental seals, but they have a wide open top cap that can be flushed out very quickly, no tiny holes to worry about.

 

[SubAquatix]

Larry,

Don't leave out the Mark 18. While no longer available in the US, it is still an active first stage outside of the US, and a dynamite rig.

 

[CAPTAIN SINBAD]

I had an Atomic Z2 and it breathed better than anything I ever used. I also went against manufacturer recommendations and used it UNSEALED in upper 30s water without a free flow. Yet as per manufacturer recommendations the chance of a free flow was high and the whole process of sealing it sounded a bit bizarre and expensive so I sold it and got Apeks. I have never heard anyone in Northern Canada or Northern Europe swearing by Atomics even though Atomics claims that it has a dedicated ice diving model. If anyone has used the M1 in Arctic or ice conditions then I would love to hear about their experience.

 

[ams511]

Larry,

Don't leave out the Mark 18. While no longer available in the US, it is still an active first stage outside of the US, and a dynamite rig.

From what I remember a MK-18 was just a MK-14 (Where does SP get these numbers from?) with a turret. If you are talking about a MK-19 which is a MK-17 with a turret, it was never released in the U.S.

---------- Post added January 18th, 2015 at 10:45 PM ----------

Not sure of what/who you are responding to but if you are referring to the Atomic M1 regulator, you are wrong on all counts. Take a look at Atomic's website and visit their regulator page and learn the facts.

I am not sure who he is responding to either but his information is largely correct. My only disagreement is a minor one that people using air or banked recreational nitrox could get by using Dow 111 instead of Christolube which would reduce the cost of the service. Another problem with using grease is that it could trap water, causing internal corrosion of the regulator.

 

[DA Aquamaster]

Larry,

Don't leave out the Mark 18. While no longer available in the US, it is still an active first stage outside of the US, and a dynamite rig.

NBot leaving it out so much as not overly complicating it.

My understanding is that the MK 17 and Mk 19 were not marketed in the US, due primarily to Scubapro's marketing in the US of creating entry level, intermediate and advanced reg packages and forcing you to upgrade to a higher package to get some features, combined with Scubapro's long history of marketing a piston reg as the flagship reg in the US market. That meant the Mk 18 and Mk 19 were seen as potentially stealing sales from the Mk 25, so their turret-less Mk 16 and 17 counterparts were sold in the use as an intermediate level reg. That's ironic as for technical wreck and cave diving I've found the Mk 17 to be a far better first stage than the Mk 25.

Europe is more diaphragm centric, so the 18 and 19 were marketed heavily there as flagship regs.

From what I remember a MK-18 was just a MK-14 (Where does SP get these numbers from?) with a turret. If you are talking about a MK-19 which is a MK-17 with a turret, it was never released in the U.S.

---------- Post added January 18th, 2015 at 10:45 PM ----------



I am not sure who he is responding to either but his information is largely correct. My only disagreement is a minor one that people using air or banked recreational nitrox could get by using Dow 111 instead of Christolube which would reduce the cost of the service. Another problem with using grease is that it could trap water, causing internal corrosion of the regulator.

The Mk 14 had a turret. The Mk 18 is a Mk 16 with a Turret. Similarly, the Mk 19 is a Mk 17 with a turret.

You are correct that Dow 111 silicone can be used instead of Christolube for SPEC chamber applications, pretty much regardless of the breathing gas used.

The problem with keeping Dow 111 on the bench for external use alongside Christolube for internal use was the difficulty in preventing cross contamination of tools, mats, parts, etc when the tech is also trying to keep things clean when servicing regs, valves and tanks that may be used with high O2 percentage gases and/or in O2 service. Scubapro just elected to remove Dow 111 entirely from the bench to prevent that problem.

 

[MichigandiverJon]

From what I remember a MK-18 was just a MK-14 (Where does SP get these numbers from?) with a turret. If you are talking about a MK-19 which is a MK-17 with a turret, it was never released in the U.S.

---------- Post added January 18th, 2015 at 10:45 PM ----------



I am not sure who he is responding to either but his information is largely correct. My only disagreement is a minor one that people using air or banked recreational nitrox could get by using Dow 111 instead of Christolube which would reduce the cost of the service. Another problem with using grease is that it could trap water, causing internal corrosion of the regulator.

My instructor/ friend at my LDS won't "seal" the Atomics or other piston style regs with anything if they're being used in saltwater. He says they still get some water intrusion and it causes corrosion issues. He said it isn't as much of a problem in freshwater.

 

[ams511]

The Mk 14 had a turret. The Mk 18 is a Mk 16 with a Turret. Similarly, the Mk 19 is a Mk 17 with a turret.

You are correct that Dow 111 silicone can be used instead of Christolube for SPEC chamber applications, pretty much regardless of the breathing gas used.

The problem with keeping Dow 111 on the bench for external use alongside Christolube for internal use was the difficulty in preventing cross contamination of tools, mats, parts, etc when the tech is also trying to keep things clean when servicing regs, valves and tanks that may be used with high O2 percentage gases and/or in O2 service. Scubapro just elected to remove Dow 111 entirely from the bench to prevent that problem.

Thanks for correcting me on the SP marks.

---------- Post added January 20th, 2015 at 08:13 AM ----------

My instructor/ friend at my LDS won't "seal" the Atomics or other piston style regs with anything if they're being used in saltwater. He says they still get some water intrusion and it causes corrosion issues. He said it isn't as much of a problem in freshwater.

Your friend is correct. Even if it is done correctly without bubbles in the beginning, over time some of the grease does work its way out. Especially as Tbone mentions if you use the same regulator for tropical diving where it is going to see heat.