Scubapro MK2 Plus/R295 Regulator as Starter

[nomro]

I have an MK11 with R395 second stage and R295 octopus and it works great , MK11 is a balanced diaphragm reg which provides better performance at all pressure conditions and any tank status even when you are low on air.

 

[halocline]

f
Got a editors choice from the padi magazine.

that's right up there with a grammy as far as a meaningless award.

 

[Hollywoodivers]

I like the 295 over the larger second stages. Inhalation feels about the same but it doesn't move around as much on exhalation. It's easier to grip with the mouthpiece.

 

[DA Aquamaster]

for 2011 scubapro is offering the mk11/(c200/c300) in their "budget" range.

Got a editors choice from the padi magazine. Any thoughts? probably right in that same price range except a balanced, brand new design, albeit diaphragm.

I tend to agree with one of the previous posters that a "testers choice" award is meaningless and sometimes is worse than useless. I have at times been totally amazed at the crap some of those morons have responded favorably too.

I had the opportunity to look at the C200 and C300 at a tech seminar last weekend.

My overall impression is very favorable, with one or two reservations I'll discuss at the end.

The R295 is on it's way out and I suspect in a year or two it will be closed out completely. It will still be supported for decades, but it is an old design and was never what I would call a stellar performer. Frankly the 70s and 80s era 108 has always out performed it in my opinion and I always felt the R190 thru R395 series got less than stellar quality control as the specs never really required great quality. Thus the performance of regs in that series tends to vary a lot, and along with that you get people who love them and people who are a lot less in love with them.

The Mk 2 is a fine reg, but it has some serious limitations due to the nature of it's flow by design. At best, gas has to pass through a neccesarily small orifice and then squeeze past the "flow by" seat. Both factors conspire to limit flow to 92 SCFM even at full tank pressure. Since it is unbalanced the Intermediate Pressure (IP) also drops about 20 psi as tank pressure falls, so an unbalanced second stage will experience an increase in inhalation effort as the IP (and the downstream force) of the gas is reduced.

That poses some additional limitations on the Mk 2/R295 combination. It is still a good reg for most recreational purposes but it is not great and if you use something better, you definitely notice the difference.

The Mk 11 flows almost twice as much gas as the Mk 2 and is balanced so you won't overbreathe the first stage and the IP will remain stable, allowing for maximum performance from an unbalanced second stage like the C200 or C300.

Now the good stuff...

The C200 and C300 are very simple designs with very low parts counts and very nicely designed cases and air barrels that are intended to get maximum performance out of an unblanced second stage design. And they do exactly that with minimal differences in inhalation or exhalation effort compared to an S600. The difference in inhalation effort is perhaps .1" of water, but the airflow on the C200 and C300 is (in my subjective opinion) smoother due to the air barrel and flow vane design.

The C300 adds an adjustment knob and is in general principle an R109 "Adjustable", but in greatly improved and modernized form.

The as yet to be determined stuff...

I was an early adopter of the X650, buying one of the first off the line for testing, and I also bought one of the last ones made. It never really hit the mark in terms of design potential and despite some recalls and revisions, it never really got much better from start to finish - just less problematic.

It has donated some design features and parts to the excellent A700, and it has also donated some features of it's lever and air barrel to the C200/C300. As in the A700 the general air barrel and flow vane design should be stellar, but the lever still worries me.

It is a bent rod that runs through two small holes in the case engaging the poppet through a single surface. The good news is that:

1. the poppet will never jump the tabs on the lever
2. Scubapro, having learned from the whole X650 thing is carefully inspecting each and every lever, rather than a 10% sample of a production lot, and the quality appears to be excellent.
3. Scubapro got rid of the guide rails used on the X650 poppet and is using a pair of squared off sides on the rear of the poppet to keep the poppet properly oriented - something that should prevent the degraded performance issues the X650 was prone to having when exposed to sand, etc., and
4. Scubaporo appears to have done a lot more field testing of the C200 and C300.

However, despite extensive real world testing in recreational diving conditions, it does not appear (at least as far as I was able to determine) that Scubapro has tested the reg in some of the more demanding technical environments (cave diving in extensive sand, silt, etc), so I am reserving judgement on that until I actually get to try one of my own and dive one in those conditions. That may take awhile as I have to order one and wait for it like everyone else.

----

But in short, for recreational purposes I'd get a Mk 11 C200 or Mk 11 C300 long before I'd buy a Mk 2 R295. They will perform far better and most divers are unlikely to ever outgrow either of them as they will flow bags of gas and deliver very good objective and subjective breathing performance.

 

[halocline]

I would love to see a schematic for the A700. I'm also glad to see SP go in the direction of low cost barrel poppet 2nd stages, which I guess is what you're describing for the new C200-300. Because the 109 is undeniably one of the most successful 2nd stage designs in history, with many thousands still in service decades after production, it's hard to imagine too much improvement.

Thanks to DA aquamaster for yet another extremely informative post!

 

[cbrich]

I would love to see a schematic for the A700. I'm also glad to see SP go in the direction of low cost barrel poppet 2nd stages, which I guess is what you're describing for the new C200-300. Because the 109 is undeniably one of the most successful 2nd stage designs in history, with many thousands still in service decades after production, it's hard to imagine too much improvement.

Thanks to DA aquamaster for yet another extremely informative post!

Think S600, the internals are the same.

 

[halocline]

Think S600, the internals are the same.

I thought the A700 and S600 used different poppets.

 

[jffknapp]

For the price you can get a much better 1st Stage like a Mk11 or even better the Mk17 which is sealed. The performance advantages of a diaphragm are too great compared to a sport piston. Enjoy the better breathing and steadier intermediate pressure of a balanced diaphragm or even the balanced piston Mk25 (although not one of my personal faves). Diaphragms are way easier to adjust and service, especially as the reg gets on in age.

Just remember that "workhorses" are great for hauling stuff and doing manual labor. You want something smooth and easy. Spend the extra $100 and go with a Mk17 or at least a Mk11 w/ the S600.

 

[msg]

I have a MK2/190 setup and a MK20/D400 setup. The only reason I went to a different reg was the fact that the MK2 is unbalanced. The MK20 is on the way back to SP, it is leaking air from the turret. It is all good until its broke.

 

[Couv]

I would love to see a schematic for the A700.

How about a 3D animation?
YouTube - SCUBAPRO A700 second stage in detail

Thanks to DA aquamaster for yet another extremely informative post!

Ditto!