SP MK17 vs MK14

[mahjong]

Does anyone know how an earlier Scubapro diaphragm 1st stage like the MK14 stacks up against and differs from the new MK17? The MK14 has a swivel port cap. Why would the MK17 have dispensed with this? Is there some technological gain made possible by doing away with the swivel? I am only just now beginning to notice and contemplate the diaphragm 1st stage, after years of using only Scubapro piston regs, so I know very little about them. Thanks, Mahjong

 

[DA Aquamaster]

The Mk 14 is a much older design and was essentially put in production as a stop gap measure for divers who wanted a diaphragm design until the Mk 16 and Mk 18 could be fully developed. The Mk 17 was an evolutionary development of the Mk 16.

The MK 16 and Mk 18 were essentially identical designs except the Mk 18 routed the air forward to LP ports in a swivel cap rather than directly out LP ports in the sides as was done in the Mk16. The advantage of the side mounted ports are that flow rates can usually be increased due to a venturi effect that can be created.

The Mk 14 and Mk 17 designs are very different internally although my understanding is that the seat/seat guide design in the Mk 17 is closer to that used in the Mk 14 than in the Mk 16, from which the Mk 17 was developed.

Personally I was a die hard Scubapro balanced piston fan and have used every SP piston reg from the Mk 5 onward to the MK 25. But none the less I switched to the Mk 17 last year due to it's bullet proof cold water performance and due to what I feel is better routing on doubles.

A swivel is nice, but even on single tanks, I don't see that much of a disadvantage with a non-swivel ported reg when you are using 4 LP hoses anyway.

In my opinion the Mk 17 is a superb performing reg that is absolutely reliable in cold water that would freeze up a Mk 25 and is lighter and more compact to boot.

 

[mahjong]

Thanks DA. Given that a diaphragm reg is environmentally sealed, it would certainly seem to make good sense for many diving environments. In fact, if the breathing characteristics of a diaphragm reg like the MK17 are comparable even to an older piston reg like the MK10--and given that the MK17 is smaller, lighter, and no more expenseive than high-end piston regs--then why will we continue to have piston regs at all? From what I've read so far, the only possible edge the piston reg may have over the MK17 is that the piston reg is simpler in design, which seems to be an issue only for servicing/maintenance and not for performance reliability. Mahjong

 

[DA Aquamaster]

I switched form MK 20's and MK 25's to MK 17's with my D400 second stages and I could tell absolutely no difference in performance. And if you can't tell with a D400 tuned to .7-.8 inches of water, you just can't tell period.

The flow rate for the Mk 17 is listed at 177 SCFM which is more than enough gas for any deep air or trimix application. For comparision purposes a MK 10 produces flow rates in the 110-125 SCFM range.

The MK 25 is rated at 300 SCFM however in practice the flow rate is lower for a Mk 25 configured for cold water use as the IP is normally lowered to around 120-125 psi rather than 145 psi and I estimate the actual flow rate in that condition is probably around 250 SCFM. So you are not really giving up all that much performance compared to a MK 17.

My opinion is that with the Mk 17, Scubapro finally has an excellent performing fully sealed regulator design that can beat the existing competition (Apeks). Personally, I see no need to continue with the Mk 25 as the Mk 17 is a better reg overall and if the trend I see on foreign SP sites continues, I suspect the MK 17 will be marketed in many more standard packages in the US in the next couple years. As it is, you can still custom order the Mk 17 with any SP second stage. It will take your LDS a week to 10 days to get it from Scuabpro.

 

[alo100]

That's how I thought of it too. The very big competitors Apeks and Scubpro, are competing head to head world wide. The big reason why people are choosing Apeks is because the the seal feature. Mk17 is a new sealed product comparing to Mk25 non-sealed, a surprise to me; however, when I think of how Apeks sealed product, I can imagine that Mk17 can be used to test water. It is possible that the next sealed ScubaPro product can be a big jump in price, if the Mk17 has some good feedback.

I am not an expert, also want to hear from you guys. Who is going to win in the future,
camparing Apeks with Scubapro?
Price wise, Apeks is expensive. In many international sites, Scubapro seems to be able to offer a bit more sites that can offer parts in the whole world (maybe?). Plus, in many places I know of, Apeks always sell their products in package, e.g. Apeks 200 always comes with the 1st stage FSR, hardly you can buy only the 2nd stage. Scubapro is more flexible in terms of that. However, Apeks is more famous for their sealed products.

 

[DA Aquamaster]

Scubapro did some head to head cold water testing and I do not recall all the results other than that the Mk 17 was the only reg to survive testing in 35 degree water at high flow rates at 165 ft for the entire 200 minutes.

It is REALLY freeze resistant compared to anything else available.

What does not make sense to me is Scubapro's planned introduction of the Mk 11 - a new unsealed diaphragm design. From what I have heard so far, the price difference between the Mk 11 and Mk 17 would be very small, so why would anyone opt for a Mk 11?

 

[ScubaMilo]

DA Aquamaster wrote:
What does not make sense to me is Scubapro's planned introduction of the Mk 11 - a new unsealed diaphragm design. From what I have heard so far, the price difference between the Mk 11 and Mk 17 would be very small, so why would anyone opt for a Mk 11?

Very true with only $40.00 difference seperating the mk11($193.00) retail price from the mk17($233.00) retail price for first stages only. it would be sad to see anyone not paying the difference to get one of the best new regs availiable. IMO (mk11 looks like a very slightly remodelded mk16).

 

[amascuba]

My LDS has been pushing me towards an MK25 setup. Personally I would rather have the MK17 because it's environmentally sealed and because I'm always a little leary of the turret on the MK25. To me the swivel port is just one more thing that can break.

 

[Greg Barlow]

That's how I thought of it too. The very big competitors Apeks and Scubpro, are competing head to head world wide. The big reason why people are choosing Apeks is because the the seal feature.

Apeks uses a metal air barrel in the second stage. This is a BIG plus over the plastic air barrel that ScubaPro has gone to to make the bean counters happy. This is NO reason for ScubaPro to do so. There is a valid reason why Atomic and Apeks still use metal in this part, and that is its thermal benefits.

If ScubaPro really wants to build a cold water reg that can compete against Apeks then they should go back to the original design, along with the new sealed diaphragm first stage.

When I started diving back in the 70's with unsealed diaphragm first stages and all metal second stages, free flows were about as rare as hen's teeth. With my Mares and Apeks regs I have never had one hint of a free flow, and most of my dives are in water colder than 45 degrees. Heck, last week I dove in 38 degree water with my MR12 Akros regs (on doubles, and unsealed) and they worked great. Come to think of it....The only free flows that I have seen with my dive buddies are from those divers using "high performance" balanced piston first stages. When you move air volumes of that magnitude there is a lot of temperature drop in a first stage.

Me? I'll stick to the balanced diaprhragm with their lowly flow rates of 140-180 cubic feet per minute. Considering that second stages generally don't flow more than 70cfm, that is more than enough for me and a buddy.

Greg Barlow
Former Science Editor for Rodale's Scuba Diving Magazine

 

[ScubaMilo]

I've been diving mk20 and mk25 first stages as long as I've been diving never had a problem with the turret failing. I would say I am hard to very hard on my gear but do keep up on regular service. I think the mk 17 will be a great addition to the scubapro line up. Although I do not see it totally replacing the mk25 any time soon.