identify mk25 vs mk20

Can anyone tell me how to positively identify a mk25 1st as opposed to a mk20 (aside from the printing on the yoke screw).

Thanks and regards
Bluey

No.

The early Mk 25's had the non-finned swivel cap. The finned cap came along around June-July 2003.

The Mk 20 became the Mk 25 the day SP added the new seat carrier with the IP adjustment. Otherwise the two were exactly the same the day that occured on the Mk 20 production line.

The late production Mk 20 already had the larger ambient pressure holes in the swivel cap, the comopsite piston and the new "Mk 25" yoke/DIN retainer. Since it became the Mk 25, there have been some slight changes in the TIS system (minor change to the composite piston, change in the piston bushing, changes to the rubber piston stem boot), the change to the finned swivel cap, a restyled LP port turret and a new yoke screw.

So in effect, the progression from early production Mk 20 to current production Mk 25 is a slow gradual evolutionary process with no clear definition of a Mk 20 versus a MK 25 other than the adjustable IP seat retainer - and that can be retrofitted as can all the other later Mk 25 parts, so that difference is basically meaningless.

SP should have just stayed with the Mk 20 numeration as the regs are effectively the same, but I suspect the marketing folks wanted a "new" first stage to market. I think it is also significant that the styling changes such as the new finned turret occurred within about a year of the Mk 25's introduction and suspect this may have had more to do with the difficulty in convincing Mk 20 owners to buy a "new" Mk 25 that looked exactly the same as their old Mk 20 than with improving heat transfer.

Thanks very much. More than helpful.

Bluey

hmm, my mk 25 has black rubber around the yoke clamp, and i'm not positive, but i think the mk 20's are just bare metal. Atleast the mk 20's I used when i was doing my ow cert were bare metal. may not be the best indicator, but it is all i could think of.

well, the Mk 25's i have seen have a sort of "thread" middle which the Mk 20's i've seen don't have

see the "thread" looking things in the middle? the Mk 20's shouldn't have that. it should just be flat metal

http://shop.scuba.co.uk/ProductImages/mk25r390.jpg

YMMV, i dont' really know Scubapro regs at all

The MK25 has five circular little flanges on the first stage near the high/low pressure ports. The MK 20 does not have this. I believe that the MK25 is a bit longer than the MK20 as well. Here is a pic of a MK25 (notice the flanges).

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