Is the mk25 superior to the mk17???

[gmudiver]

Im looking at getting one of these two first stages paired to a S600 second.

ScubaPro seems the market the mk25 as a higher preforming reg, with the mk17 coming in second. And it seems a lot of people if they have both use it as their first choice.

I know the mk25 is piston, and the mk17 is a diaphragm and environmentally sealed.

To me the mk17 seems to have a wider temperature range in which you can dive it in, and also because its sealed would be more reliable due to keeping out contaminates...right?

So what gives the Mk25 an edge (if any) over the mk17. Are there benefits to a non-sealed piston design that I'm just not seeing?

 

[walke121]

Depends on the type of diving. The MK25 is a balanced piston and does breathe better than the MK17. The MK17 being a diaphragm reg is better suited for cold water. I personally prefer the MK25 but if diving water that is cold I might consider switching to a MK17. I do know people that use the MK25 for cold water and have not had issues but I have seen a few cases where free flow was a problem.

 

[adm3745]

This thread just came up a little while ago. The Mk25 has a higher flow rate around 300cft/min if I recall. The Mk25 has the swivel as well as the bottom LP port so I think hose routing is a little better. I suppose if your in cold water get the MK 17. Otherwise i'd just go by what feels good to you. I dive MK25's but my buddy just bought new Mk17 and I like that just as much now.

http://www.scubaboard.com/forums/technical-diving-specialties/306467-mk11-mk17-mk25.html

 

[bajashack]

You have to dive REALLY COLD water to get the benefits of the M17 I have been diving the Pacific Northwest for several years with two MK25... Never a problem The average water temp for my diving is high 40 to low 50.

 

[Jorgy]

Less than 42 degree water go with the MK17.........

MK25 is a sweet reg my darling bride dives it now as she only dives warmer water.....

Free flowed twice on me, so I bought a Poseidon.......

Just my experience, I have heard of the MK25 working in really cold water but not in my case.....

Maybe I have bad cold water technique...but the Poseidon is free flow free.......

M

 

[gmudiver]

Depends on the type of diving. The MK25 is a balanced piston and does breathe better than the MK17. The MK17 being a diaphragm reg is better suited for cold water. I personally prefer the MK25 but if diving water that is cold I might consider switching to a MK17. I do know people that use the MK25 for cold water and have not had issues but I have seen a few cases where free flow was a problem.

Are all piston designed regs inherently better flowing then diaphragm styles?

 

[walke121]

MK25 has about 300 SCFM (standard cubic ft. per minute) of flow rate. The MK17 is about 175 SCFM. That being said that is tons of performance from each 1st stage. But to answer your question the MK25 is higher in performance.

 

[halocline]

What's the difference between 300SCFM and 175SCFM? It's the ability to theoretically drain an AL80 in 15.4 seconds vs 26.4 seconds.

Since we all know that opening a tank valve on an AL80 will not drain the tank in anywhere near that amount of time, it's clear that the flow rate on both regs far exceeds that of the tank valve. So someone tell me how a MK25 "breathes better" due to the higher flow.

I'm a big fan of SP balanced piston regs, I have a bunch of them, but the flow rate is just not that important. What is important IMO is the great IP stability and lightning fast lock up they have over the long haul.

 

[gmudiver]

Thanks everyone for the great answers!
What about the mk25 not being sealed, has that given Anyone problems for example if your diving in merky waters?

 

[walke121]

Thanks everyone for the great answers!
What about the mk25 not being sealed, has that given Anyone problems for example if your diving in merky waters?

In college I worked on boat docks in a lake. I made sure I rinsed it well after every dive and that seemed to work fine.