ScubaPro MK25s

[TSandM]

The MK25s have a reputation for not being good cold water regs, and I believe DA Aquamaster has posted a discussion of the design considerations that make that true. However, it may depend on how you define cold water. I have had mine for about three and a half years, and dive in water down to the mid to low 40's with air temps in the 20s on occasion. I'm careful not to prebreathe them on land when it's that cold, but otherwise I use them normally and I have not had any problems with freeflowing. (On the other hand, I've had two freeflows with the diaphragm Aqualung Titans in the same kind of conditions.)

I think they are fantastic regulators.

 

[ScubaFeenD]

There are quarries in my area that can get into the upper 30s (F of course). I havent dived them yet, but I want to be sure that I can if I want--sadly not too many ocean dives are to be had in the winter months here. I will have to try them and see how I like them. I did get an amazing deal on them, so if I needed to turn around and sell them I probably could. I might also be able to use them as deco regs as well, so the purchase was not a waste by any stretch of the imagination.

Thank you all for sharing your experience and recommendations. I know more of what to look out for now, and I will search out this DA Aquamaster you refer to and find his posts on the MK25.

 

[Txfirefighter4305]

Well, I guess its some consolation that my cold water diving promises to be with a FFM anyway. I need one of those and a dry suit anyway. Not much for the cold.

Here's a thought. What about an in-line shut off for each second stage in case of a free flow? at least you wouldn't loose gas that way.

 

[halocline]

The MK25 does have a checkered reputation in extremely cold water, especially in combination with the S600, which lacks the heat transfer qualities of the G250V or A700. OTOH, it is also one of the most popular and widely used 1st stages for technical diving, including very cold water, so I guess you can give it a try and see what happens. It is true that the MK25 is not a sealed 1st stage, but there are some anti-freezing refinements that have been incorporated. If you have a choice of 2nd stages, go for the G250V or A700, both have metal parts which radically improve heat transfer and could help to forestall a 2nd stage freeze-up which could in turn cool the 1st stage to freezing.

All this information is based on reading and talking with knowledgeable people, I'm happy to say. Maybe someday I'll venture into cold water diving, but not yet.

 

[Belce]

Regardless of its checkered reputation the Mk25 with the S600 the combo has earned approval for use by the US Navy to 190' and 38 F.

The greatest potential for a free flow is at the start of the dive at the surface in cold air temps and when you just go in.

 

[tomich]

Is there a reason you wouldn't consider the MK17 instead?

 

[Splitlip]

The 25's are pistons. The only way to convert a piston for really cold water is to "grease" them.

That really is not an environmental seal. Better off with the MK17.

Having said that, I have 2 MK 25's. (and would gladly relieve you of one of the 1st stages )