ScubaPro MK25 or MK25AF

[NudeDiver]

Which one of these do I have? The MK25 or 25AF??

Thanks
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[HatchetJoe]

It has been been my understanding that the MK25 and Mk25AF are identical except that in the AF version some brass&chrome parts have been replaced by aluminum. Someone please correct me if this not correct.

 

[SDAnderson]

The regulator in the photo has the AF finned cap installed.

 

[DA Aquamaster]

There is no such thing as a MK 25 "AF". The "AF" just refers to any Mk 25 with the full battery of antifreeze components. The most visible one is the finned swivel cap, but the full AF kit came out a few months after the finned swivel cap and what consititutes the AF parts changes now and then as SP contiues to update the reg and AF parts.

Essentially, all the AF parts except the swivel cap and the in some cases the piston in very early Mk 25's are added and/or replaced with the annual service kit. The very early Mk 25 piston was the composite piston currently used but had a slightly less polished piston stem so it is no big deal. The finned cap can be retrofitted, but then does not perfectly match the LP port turret so replacing them both is needed if you want the current MK 25 "look" and the dealer cost for the parts is probably about $50.

For that matter if you also add the Mk 25 seat retainer (a waste of time that just adds a potential source of leaks) and ensure it has a composite piston, any Mk 20 can be brought up to the current Mk 25 "AF" standard.

The Mk 25 SA (stainless steel/Aluminum) was a lighter weight version of the Mk 25. It was an attempt to create a MK 20 UL (ultralight) counterpart without the durability issues that plauged that reg so some of the aluminum parts were replaced with stainless steel. It also has the relevent parts of the "AF" kit.

 

[NudeDiver]

Thanks all.

Any chance someone can post a photo of the "non-finned cap" so I can see what you guys are referring to here?

Thanks!
nd

 

[pescador775]

Non finned regulator

 

[NudeDiver]

Oh, wow, that looks a lot different from mine. And that's an MK25 too? OK - I get it now. Thanks for posting that

So, now I wonder if the people that say the MK25 isn't too great for cold water and a lot of people have them freeze up, are talking about the smooth one rather than the ribbed one like mine, or if the people that have the ribbed one also have problems.

 

[pescador775]

Two-three years ago, some European dive mag tested the MK25AF (yes, there was an AF in Europe for about a month) in a cold lake and the reg froze up. Pizzed the guy off a bit, too. Hey, did you not know, it's all about "technique"? When the thing freezes, spit it out and use another regulator.

 

[DA Aquamaster]

Oh, wow, that looks a lot different from mine. And that's an MK25 too? OK - I get it now. Thanks for posting that

So, now I wonder if the people that say the MK25 isn't too great for cold water and a lot of people have them freeze up, are talking about the smooth one rather than the ribbed one like mine, or if the people that have the ribbed one also have problems.

The Mk 25 followed ther Mk 20 on the production line and both regs have evolved during their production runs. I owned one of the last Mk 20's made and one of the first Mk 25's and they were identical in all respects - except for the adjustable seat carrier that defined a Mk 25 versus a Mk 20.

The Mk 20 has since continued to evolve with larger oval shaped holes in the swivel cap and eventually the newer finned cap and restyled LP port turret.

With or without all the AF kit features, the M 20 and Mk 25 have been marginal in very cold water (below about 45 degrees). When I dove Mk 20's and 25's on my doubles, I used the Mk 15 SPEC boot and silicone filled ambient chambers to avoid potential freeze flows in 35 degree water. It is not a guarenteed problem, but the Mk 25 does demand perfect cold water technique to avoid a freeflow when the temps fall below 45 degrees.

That is why I switched to MK 17's - they are basically bullet proof in cold water.

 

[John_B]

So, now I wonder if the people that say the MK25 isn't too great for cold water and a lot of people have them freeze up, are talking about the smooth one rather than the ribbed one like mine, or if the people that have the ribbed one also have problems.

No, people are getting freeflows with the finned version MK25 in cold water. I have a dive buddy who finally gave up on his freeflowing MK25s/S600s and got MK17s/G250Vs that haven't given him a bit of trouble.