Scubapro naming convention?
- Thread starter BassO
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
ginti
Contributor
but we would go too much OT... 
I’m sure, if you shore dive in time it will degrade the chrome sealing surface, it’s just a matter of time. It will take many years though, my last regular use MK 25 was pretty sorry looking inside after 10 years of heavy (ish) use but it still worked so it may be one of those 20 year to failure things.
I ended up going to Atomic and now the MK17, it’s sealed so maintenance is a snap and the service life is longer without worry of internal wear. Higher flow is meaningless in real life. I like the look of the Sherwood SR 2 as it has a nice modern streamlined style but the MK17/D420 is doing all I want from a regulator.
My older MK5 was manufactured in 1976 and some 20 years ago it had problems due to partially damaged chrome finish of the internal surface where the piston O-ring works.
Small bubbles leaking from holes (the reg was still breathing great).
I had to polish the surface with my Dremel.
The problem reappeared 2 years later, requiring another polishing, which in practice removed all the chrome remaining.
After this, being no more chrome over the brass, the reg worked regularly without loosing bubbles anymore for the last 18 years.
So I can confirm that a SP piston reg without SPEC can suffer of this problem when the chrome layer
is scratched and partially removed, but afterwords, with no more chrome on the surface, it comes back to be reliable again.
My other 3 MK5 have the SPEC and I did always pack the chamber full of silicon grease at every service. They have more than 40 years of use, during which they made around 1500 dives, and I never got any tiny air bubbles escaping from them.
The SPEC system was really great, it touched its higher vertex with the MK10 and its rubber boot.
I do not understand why SP moved away from it and switched to the current AF (anti freeze) technology... Which apparently is also quite good for cold water (the MK25 got certified for cold water according to the severe EN standard, as the MK17), but does not provide the same protection against abrasive dirty water or other pollutants.
Small bubbles leaking from holes (the reg was still breathing great).
I had to polish the surface with my Dremel.
The problem reappeared 2 years later, requiring another polishing, which in practice removed all the chrome remaining.
After this, being no more chrome over the brass, the reg worked regularly without loosing bubbles anymore for the last 18 years.
So I can confirm that a SP piston reg without SPEC can suffer of this problem when the chrome layer
is scratched and partially removed, but afterwords, with no more chrome on the surface, it comes back to be reliable again.
My other 3 MK5 have the SPEC and I did always pack the chamber full of silicon grease at every service. They have more than 40 years of use, during which they made around 1500 dives, and I never got any tiny air bubbles escaping from them.
The SPEC system was really great, it touched its higher vertex with the MK10 and its rubber boot.
I do not understand why SP moved away from it and switched to the current AF (anti freeze) technology... Which apparently is also quite good for cold water (the MK25 got certified for cold water according to the severe EN standard, as the MK17), but does not provide the same protection against abrasive dirty water or other pollutants.
The Sherwood SR-2 may have the largest flow of any piston in the world. It was specifically designed to beat the Mk25, if I recall correctly from the original SR-1 seminar. It has an overbalanced piston with the biggest bore I've ever seen. The larger knife edge diameter actually requires that the piston be assembled during service, because the knife edge is too big to fit past the shaft oring.
The DRY balance system is frigging elegant! That weird part #15 above is a force transmitter that sits underneath an environmental diaphragm and transmits ambient pressure to the piston head. #18 on the right pushes on a rigid disc #7, which is in contact with the three legs of #15 and augments the piston spring with ambient pressure!!!
There are a lot of parts for a piston, which @couv will hate. But it is an engineering marvel.
The second stage
is a standard barrel design, most closely related to the G260. The plastics are a bit lighter weight, which is both good and bad. It's an easier mouthfeel than the G260, but probably not as tolerant of abuse. IMO, it's certainly prettier as a regulator.
The second stage has a floating orifice like Atomic, which should markedly prolong seat life, and has a unique external adjustment mechanism (part #17) which obviates the need for an in-line adjuster to change cracking effort! Great for the shop technician!
In a fair world, the SR-2 first stage would be the go-to reg over both Atomic and Scubapro, from a design engineering standpoint. It is truly a unique design!
1) Dry
2) Big bore piston with HUGE flow
3) No need to pack with Christolube
Getting parts from Cramer-Decker is another matter. And the technician needs to understand the design, because while the legs on that force transmitter are strong in an axial direction, you can snap them off during reassembly if your nameplate reads "Shop Monkey". They have to be high strength plastic for friction/corrosion reasons. The legs run through three tubes bored in the outer wall of the reg body. If the reg ever flooded and then sat around for more than a month, you'd never get metal legs out of the regulator due to close tolerances, a long run and corrosion. Me? I'd rather see metal. But then, I take care of my gear.
At $650, it's pricepoint leaves Scubapro in the dust. You might have to ponder between an Atomic Z and this set, but for an unsealed reg, the Mk25EVO + any 2nd is grossly overpriced.
ginti
Contributor
This is the point! The world is not fair, and one has to deal with the availability of technicians, parts, etc. Before buying the scubapro, I was more in favour of the apeks system. The xtx50 seems to perform amazingly and it's cheaper than the G260, 1+ for apeks. Also, in terms of first stage they seem to perform equally, but the apex is sealed, so another 1+ for apex = 2+. But what I change country relatively often, so what if I move to the US? They told me that apeks customer service basically doesn't exist over there... so scubapro wins.
Apeks second stage seat life is underwhelming. I really don't understand why the tec community is so enamored with the XTX50.
halocline
Contributor
First, thanks for posting that schematic. I've wondered how they seal that 1st stage. I guess the ambient chamber is routed to the area on the other side of the HP seat where pressure can be transmitted through a diaphragm. Is that '3 pin link' involved somehow?
But, fair or not, when the SR-1 came out it was kind of a disaster.(I realize they supposedly addressed those issues in the SR-2) I had a friend who is on his third regulator from Sherwood after the 1st two were replaced under warranty because they wouldn't stop creeping, and with one the ambient diaphragm popped off a couple of times. Sherwood had a reputation for bullet proof simple regulators and man was this one a departure from that philosophy.
While I'm on a rant, I'm no fan of that 2nd stage as well. To me it's everything a 2nd stage shouldn't be; overly complex, heavy handed on the venturi, and very un-natural feeling. But I'm somewhat anachronistic about regulators and am perfectly happy with my 40 yr old Mk5/10s and 109s. Especially for cave diving where I really don't care about tiny differences in breathing effort; I just want total confidence that it will work all the time with minimal attention.
Similar threads
