Info Scubapro Announces the new updated MK17 first stage, the MK17 EVO 2!!

[Nemrod]

But what if i already have 4-5 Mk25 (EVO)? Guess a few more won't hurt.

But on a serious note.. if they would come out with a G260 made from titanium for the working bits... i might buy that. Maybe even with that insanely overpriced titanium Mk25T EVO too. I just don't like the S620 X-Ti or whatever it's called over the G260.

I would personally prefer either the Mark 11 in titanium which they did some years back already or the Mark 2 Evo in titanium along with the G260 with titanium barrel.

It looks like the Mark 17 Evo 2 is a dry version of the Mark 11 Evo. Hmmm.

 

[Tanks A Lot]

I fear the end of support (service kits) for the OG 17 to force purchase.... Cause deep down, they can/will ...

I believe this fear is unfounded.

The new MK17 EVO 2 has the exact same soft parts as the MK17 EVO, which has very similar soft parts as the MK17, except some O-rings at the balance chamber. Diaphragms (Inner and outer), seat and all O-rings are unchanged on the MK17EVO 2 compared to the MK17 EVO, which makes them backwards compatible with the MK17, despite a couple of O-rings at the balance chamber. Even the orifice is interchangeable between the three.The service kit part number is (10.117.045) and now includes the MK17 EVO 2 alongside the MK17, MK17 EVO and MK19.
I'm all for giving manufacturers **** for dropping product support, but I believe we can find more deserving companies than ScubaPro to bark up that tree. They have one of the best, if not the best, track records for keeping older regulators running.

• The MK17 EVO improved upon the balance chamber and bias spring of the original MK17. Some O-rings had to be added to the service kit for the revised balance chamber.
• The MK17 EVO 2 improves on the MK17 EVO body as well as everything between the inner diaphragm, which is unchanged, and outer diaphragm, which is unchanged. Notably, the pressure transducer and an added spring inside the main bias spring are changed.

The ribs on the body are a welcome sight, it always puzzled me why most manufacturers produce mainly smooth surfaced regulators, which therefore have horrendous heat exchange properties. All of them figured out decades ago that a conical filter with its vastly superior surface area is better than a flat disc. Yet, the "flat surfaced" main body has stuck for most of the manufacturers and very few incorporate fins or ribs for heat exchange.

I'm a bit puzzled on how that new pressure transmitter works between the two diaphragms. From the drawings it looks like the transducer may not be in direct contact with the lower diaphragm disc, but a spring is inserted between the two. Either that, or (See Post 58) the piston of the transducer slides into the second spring, in which case I see the spring not doing work at all. Also the pressure transducer doesn't seem to be a one piece assembly anymore, but the disc and piston are separated.

I must admit I fail to see how that would make any improvement upon the transmission from outer diaphragm to inner diaphragm compared to the current state. But I reckon that is more due to my poor engineering understanding of the matter, rather than it having no benefit.

I'm looking forward to see the the transducer and spring in person to better understand the reasoning for including this design.

@BoltSnap Where did you get the pictures from, I have not seen ScubaPro release these yet. Would you happen to have better quality pictures that you could share, I'd like to include these in my regulator identification file.

 

[BoltSnap]

@BoltSnap Where did you get the pictures from

Screen capture of the new unpublished SP 25 product guide.

Would you happen to have better quality pictures that you could share, I'd like to include these in my regulator identification file.

No, nothing published by SP yet except for the product guide. I looked in the usual SP places but they still haven't published them yet. I suppose they will when the product is about to be released or shortly after.

 

[BoltSnap]

I believe this fear is unfounded.

The new MK17 EVO 2 has the exact same soft parts as the MK17 EVO, which has very similar soft parts as the MK17, except some O-rings at the balance chamber. Diaphragms (Inner and outer), seat and all O-rings are unchanged on the MK17EVO 2 compared to the MK17 EVO, which makes them backwards compatible with the MK17, despite a couple of O-rings at the balance chamber. Even the orifice is interchangeable between the three.The service kit part number is (10.117.045) and now includes the MK17 EVO 2 alongside the MK17, MK17 EVO and MK19.

Awesome indeed, this is why SP deep down is the best

I'm all for giving manufacturers **** for dropping product support, but I believe we can find more deserving companies than ScubaPro to bark up that tree. They have one of the best, if not the best, track records for keeping older regulators running.

They are the best in this regard nothing comes close except Atomic perhaps.

Do you think 19E and 17Eii will share service kit?
They really are looking alike again from the HP side

@Mobulai
This should answer your question:

The service kit part number is (10.117.045) and now includes the MK17 EVO 2 alongside the MK17, MK17 EVO and MK19.

 

[Wibble]

Aren’t all branded regs CE approved thus all work to the standards?

 

[Umuntu]

I'm a bit puzzled on how that new pressure transmitter works between the two diaphragms. From the drawings it looks like the transducer may not be in direct contact with the lower diaphragm disc, but a spring is inserted between the two. Either that, or the piston of the transducer slides into the second spring, in which case I see the spring not doing work at all. Also the pressure transducer doesn't seem to be a one piece assembly anymore, but the disc and piston are separated.

The exploded diagram is perhaps misleading because the components are shown spread apart for clearer illustration purposes only.

The pressure transmitter will work in the same way as in past MK 17’s, and every other sealed diaphragm regulator when properly set up. I.e., when the regulator is pressurised, the transmitter will create a direct connection between the outer and inner diaphragms, so the external pressure is constantly experienced by the inner diaphragm.

The addition of a second spring is interesting, and I question its necessity over a properly specified single spring as has been used for decades. A second more sensitive spring can theoretically react more quickly to the inhalation induced drop in IP which causes the force exerted by the spring to push the internal pin which forces the seat away from the crown and opens the regulator’s air flow. But, even if that’s the case, the timing difference compared to a properly specified single spring would be infinitesimal. The sensitive testing machines likely detected an improvement in performance.

Whether that infinitesimal performance improvement would be noticeable at the breathing effort experienced by a diver at the second stage I look forward to finding out from @BoltSnap’s review in future.

EDIT: I see that second spring as having a narrower external diameter than the larger spring’s internal diameter, but still wide enough for the transmitter to pass through the inner spring’s internal diameter. The two springs will occupy the same area, one within the other concentrically, with the transmitter passing through the centre of the inner spring.

 

[Umuntu]

Also the pressure transducer doesn't seem to be a one piece assembly anymore, but the disc and piston are separated.

The shorter body length means that they couldn’t use the “mushroom” design from the older MK17. It’s probably also less expensive to source separate disc and transmitter stem too, as the mushroom is a more complex part to manufacture.

I don’t expect it will affect performance.

 

[Tanks A Lot]

[...]
A second more sensitive spring can theoretically react more quickly to the inhalation induced drop in IP which causes the force exerted by the spring to push the internal pin which forces the seat away from the crown and opens the regulator’s air flow.
[...]

That is an interesting thought, but I'm not sure I can follow it completely after thinking about it. Here is what I think the reasoning is:

1. The big spring had to be made shorter to fit the now smaller space.
2. As the spring was made shorter, it would have lost some coils.
3. The goal was still a IP of 9.0bar to 10.0bar.
4. As coils were lost, the ability for the spring to travel would have decreased, not allowing the pin to push the seat far enough.
5. It was not feasible to reach the intended 9.0bar to 10.0bar requirement and allow for enough travel with a single spring.
6. A second, smaller spring was added.
7. The two springs are wedged between the same two surfaces at the top (spring screw) and the bottom (diaphragm disc). Therefore their total forces add up. The smaller spring is located on the inside diameter of the big spring.

As the two springs are wedged between the same two surfaces, I can't see how it could make the smaller spring react to the IP drop faster. Two springs coupled in a scenario like this should have their total forces add up at all times. In my initial reasoning I wrongly assumed that the main bias spring must be carrying the whole load, which is of course nonsense.

Things I see that could support the above are:

• Slightly narrower inter-stage pressure requirements than usually. Now it is 9.2bar - 9.8bar instead of the usual 9.0bar to 10.0bar.
• The bias spring part number has changed.
• The chamber AF part number has changed.
• The main bias spring looks smaller on the MK2 EVO 2 schematics (Yes I know, drawings don't mean all that much).

 

[Umuntu]

That is an interesting thought, but I'm not sure I can follow it completely after thinking about it. Here is what I think the reasoning is:

1. The big spring had to be made shorter to fit the now smaller space.
2. As the spring was made shorter, it would have lost some coils.
3. The goal was still a IP of 9.0bar to 10.0bar.
4. As coils were lost, the ability for the spring to travel would have decreased, not allowing the pin to push the seat far enough.
5. It was not feasible to reach the intended 9.0bar to 10.0bar requirement and allow for enough travel with a single spring.
6. A second, smaller spring was added.
7. The two springs are wedged between the same two surfaces at the top (spring screw) and the bottom (diaphragm disc). Therefore their total forces add up. The smaller spring is located on the inside diameter of the big spring.

As the two springs are wedged between the same two surfaces, I can't see how it could make the smaller spring react to the IP drop faster. Two springs coupled in a scenario like this should have their total forces add up at all times. In my initial reasoning I wrongly assumed that the main bias spring must be carrying the whole load, which is of course nonsense.

Things I see that could support the above are:

• Slightly narrower inter-stage pressure requirements than usually. Now it is 9.2bar - 9.8bar instead of the usual 9.0bar to 10.0bar.
• The bias spring part number has changed.
• The chamber AF part number has changed.
• The main bias spring looks smaller on the MK2 EVO 2 schematics (Yes I know, drawings don't mean all that much).

Other manufacturers have produced very compact sealed diaphragm 1st stages, probably more compact than the MK17, without needing a second spring. So I don’t see that as creating any necessity for a second spring. See Aqualung’s supreme versions of the last Titan, Core, Helix Compact Pro etc.

The narrower IP range is indicative of the ability to fine tune within a narrower range, which suggests greater tuning precision is possible.

The spring and chamber sizes have changed because the length has changed.

I don’t think that piston and diaphragm springs are directly comparable.

 

[BoltSnap]

Other manufacturers have produced very compact sealed diaphragm 1st stages, probably more compact than the MK17, without needing a second spring. So I don’t see that as creating any necessity for a second spring. See Aqualung’s supreme versions of the last Titan, Core, Helix Compact Pro etc.

The narrower IP range is indicative of the ability to fine tune within a narrower range, which suggests greater tuning precision is possible.

The spring and chamber sizes have changed because the length has changed.

I don’t think that piston and diaphragm springs are directly comparable.

You just have to get your own set and play with it to figure it all out genius boy