Changing over all my regs, Scubapro questions

[50Fathom]

Based on the considerations you outlined, it makes sense to "standardize" to 1 second stage (G250V) and 2 different first stages (backgas - MK17, stage - piston - MK25 or other). You're an official Scubapro reg tech with access to unlimited parts kits (for now). I don't see the big deal. If your needs change down the road, you can "revise" the regs you have in your dive closet.

The more I think about it, this isn't a bad way. And right now I'd only need a couple of stage/deco regs, since dropping stages is a long way off, so I would only be using what I was carrying.

 

[50Fathom]

There's also the fact that one kit can service multiple 2nds, like the G250, G200B, S600, Balanced Adjustable, S555, etc. can all be serviced off the same kit.

Makes second-stage options better.

 

[lowviz]

...........I was in the Army prior to this and worked in logistics. I am a HUGE fan of simplifying and streamlining, (after working in the massive bureaucracy that is Army Logistics), and if I only need one parts kit for every single 2nd stage I own and one parts kit for every single first stage I own, it makes resupply and stocking a lot easier.

I could have 10-20 parts kits each (G250/Mk17), along with a supply of commonly-broken bits, and be set for the next 5-6 years, easy....................

Consider an MK11. It is a simple conversion to an MK17 if you later become totally paranoid.

The MK25's with the rotating ports do often route better, but not always. Since you won't have that many hoses on a stage/pony, -there will be one HP and one LP port exactly where you want it. There is also a size difference between the MK25 and the MK11.

 

[50Fathom]

Consider an MK11. It is a simple conversion to an MK17 if you later become totally paranoid.

The MK25's with the rotating ports do often route better, but not always. Since you won't have that many hoses on a stage/pony, -there will be one HP and one LP port exactly where you want it. There is also a size difference between the MK25 and the MK11.

Can't believe I forgot the Mk11. A real sleeper and internally a Mk17 without the dry ambient chamber.

 

[50Fathom]

I guess it's a moot point anyhow, since I just called Scubapro and found out that they do not make O2-compatible parts kits for the diaphragm regs, (since I couldn't see any in the catalog to order). Their thinking is that they offer a high-end and low-end with available kits, (Mk25 and Mk2), so why muddy the waters with allowing the diaphragms to go above 40% O2?

I am disappointed, but not surprised. They are a piston company and only make diaphragms under duress. (Not explicitly stated, but that is what comes across whenever you discuss the diaphragm regs with them.)

Oh well. Could be worse.

 

[HenrikBP]

I guess it's a moot point anyhow, since I just called Scubapro and found out that they do not make O2-compatible parts kits for the diaphragm regs

Other than the o-rings and type of lube, is there anything to be concerned about? All the SP o-rings are standard sizes, so it shouldn't be a big deal to get the appropriate Viton o-rings.

Henrik

 

[50Fathom]

Other than the o-rings and type of lube, is there anything to be concerned about? All the SP o-rings are standard sizes, so it shouldn't be a big deal to get the appropriate Viton o-rings.

Henrik

That's actually what I'm thinking. Viton on the HP side and go from there. I would imagine the diaphragm would need to be compatible, but I'm not sure what it's made of to begin with, so it may already be.

I'll spend the afternoon with the exploded parts diagrams and cross-reference part numbers for the appropriate o-rings.

We already Christo-lube everything, whether O2-clean or not, so the lube is no worry.

 

[DA Aquamaster]

Some thoughts...

1. I also used Mk 17 G250Vs for back gas, and currently use them for sidemount regs. They work fine in either stage or deco applications.

2. If used as stage regs, I suppose they are at some risk of blowing the diaphragm if you flood them. However if you swap them undewrwater and flood them, just depress the purge when repressurizing and open the valve slowlt to (hopefully) repressurize slowly - the water then has a route to take other than through the diaphragm and that minimal risk is pretty much eliminated.

3. Scubapro is considering the need for O2 clean kits for the Mk 17. If there is enough demand, they will make them.

4. Scubapro currently makes O2 kits for the Mk 20/Mk 25 and Mk 2. However Scubapro also uses EPDM o-rings in everything anyway, so the differneces are in seat materials. As far as O2 compatibility goes, nyon 66 is not bad, the exposure time to O2 on a reg is minimal and if you prevent ignition sources, the fuel potential does not really matter. It is not Sp approved, but peopel have bene using Mk 5s, Mk 10s, Mk 10+s, and non-)2 kit equipped Mk 2s for at least a decade with good results provided proper techniques ar eused to pressurize them etc.

5. The valve is a far greater area of concern in terms of O2 clean and compatability issues.

6. In that regard, I use Mk 10 G250s on stage and deco bottles (they are cheap and I have lots already). They are readily O2 cleanable and work fine with the stock EPDM o-rings now available and the seats have over a decade of experience in high O2 applications, regardelss of whether or not they have SP approval. I would not set it up for a customer, and your mileage may very, but it's been working well for me. Not a recommendation by any means, but just food for thought.

7. Having two first stage models means I have to carry parts kits for the Mk 17, the Mk 10 and the G250/G250V. One more kit = no big deal.

8. I switched from Mk 25s to Mk 17s for backgas regs due to cold water issues. I never had one freeze up, but I had teammates who did. Salt water is not really an issue, but in fresh water once you get below about 40 degrees, perfect cold water technique is needed to prevent a freeze flow and the Mk 25 has zero margin for error. If you ever plan on doing really cold fresh water dives, get Mk 17s.

9. The Mk 17 with its sealed design stays a lot cleaner than a Mk 25. This is especially true now that I sidemount and spend more time in sand and silt. If I had not already switched to Mk 17s I would now.

10. Unlike an Apeks first stage, if the Mk 17's external diaphragm fails, you will get no loss of performance. And, due to a thinner diaphragm and an extra washer, the Mk 17 has a bit more working range in the valve and flows more gas (225 SCFM total) than the Mk 11. In short, there is no reason to go with the Mk 11 over the Mk 17.

 

[50Fathom]

Some thoughts...
2. If used as stage regs, I suppose they are at some risk of blowing the diaphragm if you flood them. However if you swap them undewrwater and flood them, just depress the purge when repressurizing and open the valve slowlt to (hopefully) repressurize slowly - the water then has a route to take other than through the diaphragm and that minimal risk is pretty much eliminated.

Awesome. Glad to hear that.

3. Scubapro is considering the need for O2 clean kits for the Mk 17. If there is enough demand, they will make them.

Let's hope they get the message.

4. Scubapro currently makes O2 kits for the Mk 20/Mk 25 and Mk 2. However Scubapro also uses EPDM o-rings in everything anyway, so the differneces are in seat materials. As far as O2 compatibility goes, nyon 66 is not bad, the exposure time to O2 on a reg is minimal and if you prevent ignition sources, the fuel potential does not really matter. It is not Sp approved, but peopel have bene using Mk 5s, Mk 10s, Mk 10+s, and non-)2 kit equipped Mk 2s for at least a decade with good results provided proper techniques ar eused to pressurize them etc.

5. The valve is a far greater area of concern in terms of O2 clean and compatability issues.

6. In that regard, I use Mk 10 G250s on stage and deco bottles (they are cheap and I have lots already). They are readily O2 cleanable and work fine with the stock EPDM o-rings now available and the seats have over a decade of experience in high O2 applications, regardelss of whether or not they have SP approval. I would not set it up for a customer, and your mileage may very, but it's been working well for me. Not a recommendation by any means, but just food for thought.

So the o-rings in the "regular" kits are already good, and the seats, though not approved for O2 use by SP, have worked fine for ages. Got it. You're right, I would never set this up on a customer's reg, but for my use...

7. Having two first stage models means I have to carry parts kits for the Mk 17, the Mk 10 and the G250/G250V. One more kit = no big deal.

I'm kinda thinking this myself.

8. I switched from Mk 25s to Mk 17s for backgas regs due to cold water issues. I never had one freeze up, but I had teammates who did. Salt water is not really an issue, but in fresh water once you get below about 40 degrees, perfect cold water technique is needed to prevent a freeze flow and the Mk 25 has zero margin for error. If you ever plan on doing really cold fresh water dives, get Mk 17s.

9. The Mk 17 with its sealed design stays a lot cleaner than a Mk 25. This is especially true now that I sidemount and spend more time in sand and silt. If I had not already switched to Mk 17s I would now.

This is why I'm going with the Mk17. Better in cold, better in funky conditions, and more inexpensive. Only at the cost of hose routing, (which is debatable), and availability of factory-authorized O2-clean kits, (which is easily overcome.)

Thanks for weighing in. You are a Scubapro guru here, and it's from reading your older posts that I am going with the Mk17s, (and wishing I had Mk19s).

 

[lowviz]

=DA Aquamaster;5817452..................the Mk 17 has a bit more working range in the valve and flows more gas (225 SCFM total) than the Mk 11. In short, there is no reason to go with the Mk 11 over the Mk 17.

Thanks for that nugget, -didn't know that.