ScubaPro MK17 vs MK25 with A700?
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halocline
Contributor
Wow, how about that! It was in the training area right near the 'underpass' to cream of wheat. I was using double 72s, DM'ing for an OW cert class. Maybe we can meet up there sometime when we're both there and I can have a breath or two off the A700! They sure looked shiny.
This forum is really something...
MK17 would get my vote...if you only have one regulator, make it the most flexable, sealed one you can.
That said, I have 2 Mk25/250V setups...but would not use them for really cold water diving.
That said, I have 2 Mk25/250V setups...but would not use them for really cold water diving.
I use a Mk25 with an A700 up here and the water is a little colder than you plan on and the air temp at surface can be even below freezing and have never had an issue with freezing. The Mk17 is a great 1st stage as well and your choice, but I see way more mk25 up here than Mk17's and have never seen or heard of trouble with them.
I have the MK17/A700. Got the MK17 based on what DA Aquamaster had written on this board comparing the 17 and 25... So far, I love the MK17/A700.
This is only one link... there are others.
http://www.scubaboard.com/forums/regulators/312359-mk25-superior-mk17.html
This is only one link... there are others.
http://www.scubaboard.com/forums/regulators/312359-mk25-superior-mk17.html
MK17/A700 is a fabulous choice if you have the budget I don't see any better options
As noted in previous posts, I switched from Mk 25s to Mk 17s soon after the Mk 17 was released. At the time I was diving exclusively in coldwater with bottom temps in the 35-39 degree range at depths to 150'. While I personally never had a freeze flow, I was with divers using the Mk 25 S600 who did. The difference may have been in technique, it may have been the difference in second stages (I used D400s and for a short while X650s), or it may have ben a combination of both.
In any event I switched as the Mk 17 is much more reliable in cold water and does not depend on perfect codl water technique to acheive it while the Mk 25 demands it at temps much below about 45 degrees, especially with the S600 due to the S600s poor heat transfer traits and a tendency for it do develop a very slight freeflow that in turn increases the heat transfer demands on the Mk 25.
I don't agree with the statement above that the Mk 25 would be a better cold water reg at 180'. I am assuming that statement is based on the Mk 25 being certified by somebody for cold water use at that depth. That would just confirm the Mk 25 meets some minimum at that depth, but does not change the fact that the Mk 17 is more reliable in cold water. This is especially true at greater depths where higher flow rates greatly increase the heat transfer demands placed on the Mk 25.
In terms of flow rate the Mk 25 will flow about 300 SCFM while the Mk 17 "only" does about 220 SCFM, but then even the highest performance second stage available only flows about 70 SCFM, so the Mk 17 has more than enough flow rate to support 3 second stages at maximum flow rates.
I also put very little value in the "most people I see use the Mk 25" argument as it is nothing more than an ad populum logical fallacy. Scubapro pushes the Mk 25 as its premier reg in the US and many Scubapro dealers and customers have 40 years of history with the basic Mk 1/5/6/8/9/10/15/20/25 piston design and are not inclined to adopt any diaphragm reg - even one that is superior in most respects to the Mk 25 and gives up nothing of value in terms of real world performance. That resistance to change has nothing to do with the actual capability of the Mk 17.
In any event I switched as the Mk 17 is much more reliable in cold water and does not depend on perfect codl water technique to acheive it while the Mk 25 demands it at temps much below about 45 degrees, especially with the S600 due to the S600s poor heat transfer traits and a tendency for it do develop a very slight freeflow that in turn increases the heat transfer demands on the Mk 25.
I don't agree with the statement above that the Mk 25 would be a better cold water reg at 180'. I am assuming that statement is based on the Mk 25 being certified by somebody for cold water use at that depth. That would just confirm the Mk 25 meets some minimum at that depth, but does not change the fact that the Mk 17 is more reliable in cold water. This is especially true at greater depths where higher flow rates greatly increase the heat transfer demands placed on the Mk 25.
In terms of flow rate the Mk 25 will flow about 300 SCFM while the Mk 17 "only" does about 220 SCFM, but then even the highest performance second stage available only flows about 70 SCFM, so the Mk 17 has more than enough flow rate to support 3 second stages at maximum flow rates.
I also put very little value in the "most people I see use the Mk 25" argument as it is nothing more than an ad populum logical fallacy. Scubapro pushes the Mk 25 as its premier reg in the US and many Scubapro dealers and customers have 40 years of history with the basic Mk 1/5/6/8/9/10/15/20/25 piston design and are not inclined to adopt any diaphragm reg - even one that is superior in most respects to the Mk 25 and gives up nothing of value in terms of real world performance. That resistance to change has nothing to do with the actual capability of the Mk 17.
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cylonboomer
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Thanks everyone for their experiences. I'm still on the fence, but have a lot to think about. One question though, and this is probably a stupid one, but does a yoke vs Dinn fitting make a difference on how the reg handles temperatures?
halocline
Contributor
Nope. Well, there is one sort of very stretched condition; DIN fittings are usually associated with higher pressures, and a reg operating under higher pressure is theoretically more likely to freeze.
So, if you're concerned about your reg freezing in 45F water (which you should not be) use lower pressure tanks. I'm still wondering where you'll find water that cold in TX. Let me know, so I can make sure to avoid it!
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