G250HP Questions

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MrSam

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My Titan has free flowed on the last 2 dives I've done. It's sitting in the shop right now, but I've decided to purchase an MK25 to use as my primary first stage (along with my B2 second stage).

I found a few that I'm interested in. One would come with a G250HP + octo for just under $300. I'm mainly interested in the MK25 but I figured I could use the G250HP as a primary to the Titan first stage (once it's fixed) and attached the B2 and Titan second stage to the MK25.
What year were the MK25's that came with the G250HP's made? I know they must have been out for a few years but around what year should I assume this specific MK25 was released?
Are the MK25's that came with the G250HP's (older style MK25's I'm assuming) up to par with today's MK25s? I can see the "fins" that are meant to prevent free flows on this specific MK25, but it still looks like an older model.

The free flows did not occur due to cold water temps. Our last dives were in 62F water, lowest was 57F if I recall correctly.
The Titan's free flow was not caused by water temp, our last dives were in around 62F water, lowest was 57F
Between the G250HP and B2, which reg is superior? I've tried a few different ones but nothing has toped the B2's super easy "pull" (almost too easy for my comfort actually; I've tried turning it down while at depth only to realize that it was already at its lowest setting, this was at around 85').
 

Fishpie

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Have you got that IP gauge yet?
Once you have it you'll find that the Titan 1st stage is simple to service with ordinary tools.

12" adjustable and CO2 cartridge......remove end cap and undo yoke nut.
Allen key.....remove adjustment nut from end cap.
Circlip pliers.....access filter, short spring, balance chamber, long spring and HP seat.
Pick.....remove balance chamber o ring.

No need to get a new old reg just fix the one you have.
 

MrSam

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Have you got that IP gauge yet?
Once you have it you'll find that the Titan 1st stage is simple to service with ordinary tools.

12" adjustable and CO2 cartridge......remove end cap and undo yoke nut.
Allen key.....remove adjustment nut from end cap.
Circlip pliers.....access filter, short spring, balance chamber, long spring and HP seat.
Pick.....remove balance chamber o ring.

No need to get a new old reg just fix the one you have.

I've yet to purchase one. Although I've found a few for $60 which seems like a fair price. The Titan is actually with my LDS right now. They were with us on the last trip and tried fixing it on the boat, but to no avail. I didn't bother asking what was wrong, simply took my buddies MK25/S600 set-up, hopped in the water and enjoyed my last dive of the day.
I did like the MK25, and owned one for a few days/used it on a few dives so I figured, why not?
 

halocline

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The MK25 is a super-high quality 1st stage that provides amazingly stable IP for hundreds of dives between rebuilds. I would actually prefer a MK20 with the MK25 piston, but I'm cranky and I don't like the external IP adjustment. I don't think there is any appreciable difference between the various MK25 years; they all came with the composite piston I believe. That piston works GREAT, but it does have a non-serviceable o-ring that eventually could fail and necessitate replacing the piston.

Of course, I'm fine with MK5s and 10s, so....
 

50Fathom

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Mk25 is a solid reg. I'm less of a fan of the G250HP, since it's 1st-gen S600 guts in a G250-sized case, and there are lots of shims and band-aids in there to make it work.

Better bet is to secure a Mk20 with a G250 (plain G250). It's better than the G250HP, IMHO, easier to service, less parts, and more common.

My brother just picked up a set of Mk20/G250s for a doubles set, (2 first stages and two second stages), and it was like less than $300 for all of them. (Closer to $250 I think)
 

axxel57

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That piston works GREAT, but it does have a non-serviceable o-ring that eventually could fail and necessitate replacing the piston

Interesting, which o-ring could that be?

Never found a non replaceable o-ring in those composite pistons..........
 

elan

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I never had a chance to disassemble the piston but on a diagram that oring is placed between the piston plastic head and the metal shaft.
If you think about for a moment you somehow need to seal the connection between the plastic head and the metal shaft and thats is what its doing
 

Zung

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Probably not "non", but the bushing is hard to remove. I once gave it a half-hearted try and failed; but since that piston is good, I didn't loose any sleep. awap has reported success, but then he's the Master...

According to EB #272, that o-ring "maintains a dry volume, which also provides additional thermal insulation", so I assume it's not a big deal even if it failed.

BTW, it's a 5-179, Duro 60, 6mm x 1mm Nitrile.
 
https://www.shearwater.com/products/peregrine/

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