Scuba Pro R190

[archman]

Does the Mk16 have a swivel? That's the only real downside I've lamented on my Mk2... it's inability to er, swivel. All my other pals have swivels, and I'm jealous.

 

[DA Aquamaster]

I also have the mk2 R190 combo and it's worked well for me. I have a question for DA Aquamaster: Do you think that an average diver will tell a difference in recreational diving environments between the Mk 2 and Mk 16, at say, 500psi tank pressure and above.... I have not noticed an increase in breathing effort until tank pressure drops below 300psi, at which point I'm typically on the surface or near the end of my safety stop.

I don't really think the average diver will notice the difference. There is an increase in inhalation resistance but it is not so great that you would notice it unless you were paying attnetion to it. As tank pressure gets closer to the IP though (below 500 psi) it will start to get quite noticeable (as you have discovered.)

and do you think that the Mk 16 is any less reliable than the Mk 2? I bought the Mk 2 because it has a reputation for being simple and bulletproof. How does the diaphragm design Mk 16 compare in that regard?

The parts count is a lot higher on the Mk 16 than with the Mk 2 Plus, but then it's not possible to get a parts count much lower than a Mk 2 as they are dirt simple. The Mk 2 Plus also has the advantage that high pressure air is not present anywhere past the seat in the regulator so the two (and only 2) dynamic o-rings are never exposed to a pressure differential greater than 145 psi. Both factors make the Mk 2 Plus super reliable.

So theroetically the Mk 16 is less relaible, but in practice if you have it serviced every year or two, the difference won't ever make a difference.

I've thought about upgrading my first stage because of the increased flow rate (although I've been hunting around for a used Mk 10 or 20) but to be honest I've never been in a situation where I felt the Mk 2 was not delivering enough air

I know several divers you use them down to 130 feet with no concerns. The Mk 2 Plus has a flow rate of about 92 scfm at a tank pressure of 3000 psi. That actually compares well to the MK 5 and Mk 10 and generally speaking a flow rate of 100 scfm is considered adequate for just about anything. The big difference in flow rates occurs at lower tank pressures where the flow rate begins to fall off on the Mk 2 whereas flow rate was much more stable on the Mk 10 as tank pressure decreased.

So the problem areas with the Mk 2 Plus would be if you found yourself diving deep or working very hard in a stong current a shallower depths with a low tank pressure. In those instances it is possible to overbreath the Mk 2 Plus. But to be fair in the case of being deep at low tank pressures, the soultion is obvious and the shortage of air itself is a much larger problem. The second case could be concern if you dive in rivers or other areas with strong current where getting back to shore along the bottom is beneficial. But worst case, you surface and swim in and just accept you are going to drift a lot farther down stream and have to walk back.

n fact, my instructor thought it might not be a bad thing to have that increase in breathing effort at low tank pressure; as a reminder to a new diver that it's time to home. (I've never had to use that reminder, but it kind of makes sense to me)

I started diving with the earlier and nearly identical Scubapro Mk 3 for this very reason. At the time SPG use was not mandatory and the early warning about a low air supply was very nice to have. This (combined with their super reliability, compact size, light weight, and limited HP spaces - which makes them a good match for O2 use) is one of the reasons I still use my Mk 3's on my deco bottles. I never get surprised with running out of gas as can happen with a high performance balanced reg that will give you only one or two breaths warning that you are running out of gas.

The Mk 2 Plus has a substantially higher flow rate than the Mk 3 so it is less limited and it has a more stable intermediate pressure to boot. So in short, unless you are planning to go below 130 ft or do hard working dives at depths below about 90-100ft, the Mk 2 Plus will work fine and I would not see a need to upgrade it.

Even if you move into technical diving where the 175 SCFM flow rate for the MK 16 is much more suitable for a primary reg, the Mk 2 Plus will still make a nice deco reg.

 

[DA Aquamaster]

Does the Mk16 have a swivel? That's the only real downside I've lamented on my Mk2... it's inability to er, swivel. All my other pals have swivels, and I'm jealous.

No. But the otherwise identical Mk 18 does have a swivel cap. The bad news is that the Mk 18 has never been widely marketed in the US. I have also heard rumors that it may also be on the way out in the European market to make room for the new and long awaited Mk 17. I did see the Mk 17 on the German SP site, but it is no longer there. And unfortunatly I did not save the schematics when I saw them there and I don't recall if it had a swivel or not. I am pretty sure it did, but I am not positive.

 

[halocline]

Thanks, DA, excellent and informative post! The one and only time I noticed my reg respond differently was at about 120 ft; and then I had no trouble getting enough air, it just seemed a little "thicker" which, of course, it was.

I remember posting here before I bought this reg, which is my first (and only) reg. Both the LDS employees and several posters on this board warned against the alleged difficulty breathing from an unbalanced reg. My instructor, (VERY experienced) and a few of the more experienced posters here understood that the differences between the mk2/R190 and a high performance, expensive regulator, are typically minimal from the point of view of a new diver like myself.

 

[Damselfish]

In fact, my instructor thought it might not be a bad thing to have that increase in breathing effort at low tank pressure; as a reminder to a new diver that it's time to home. (I've never had to use that reminder, but it kind of makes sense to me)

I don't think that makes sense - this is a really bad way to become aware of your tank pressure. It's why you see pressure gages and not J valves.

My instructor, (VERY experienced) and a few of the more experienced posters here understood that the differences between the mk2/R190 and a high performance, expensive regulator, are typically minimal from the point of view of a new diver like myself.

Perhaps true, but new divers don't stay new divers and buying twice is more expensive should you feel the need for something else later. Just something to think about.

 

[brucebowker]

I've thought about upgrading my first stage because of the increased flow rate (although I've been hunting around for a used Mk 10 or 20) )

I would opt for a Mk 20 long before a Mk 10 or a Mk 16. Mk 25 is the newest although no difference except external intermediate pressure adjustment. Handy but not necessary.

Bruce Bowker
Bonaire.

 

[archman]

It's SO nice having technical experts on the board!

Thanks for the info Aquamaster... guess I'll wait around and see about this Mk17 thing. Guess I'll keep my R190 too.

 

[halocline]

I don't think that makes sense - this is a really bad way to become aware of your tank pressure. It's why you see pressure gages and not J valves.


Perhaps true, but new divers don't stay new divers and buying twice is more expensive should you feel the need for something else later. Just something to think about.

Right, I was never suggesting that an unbalanced regulator would replace looking at guages. I guess I should have clarified that. The point is, if an inexperienced diver neglets his/her guages, this reg will give a "reminder"; of course there are other issues here.

Also, with regards to "buying twice" my point is that for myself, as is the case for all new divers, there is a confusing array of regulator choices out there, and it's impossible to know which is best for me without experience. Sure, one may be able to try out a reg in a pool a few times, maybe if you're lucky you can even rent one you're considering buying, but for most people you're much more qualified to make an informed decision about your own regulator needs after considerable diving experience. Besides, as a few people have commented on this thread, the mk2/R190 is probably an excellent back-up reg due to it's reliability and ease of service throughout the world. I suspect that as I get more experience diving, like a few hundred more logged dives, I'll look for a more high performance regulator, but I'm certain I won't regret having this one around.

 

[Muzzwezz]

Does the Mk16 have a swivel? That's the only real downside I've lamented on my Mk2... it's inability to er, swivel. All my other pals have swivels, and I'm jealous.

Whats so great about a swivvel, i heared they actually make no difference, just another thing to go wrong, marketing scheme if you like. how much difference can an inch of horozontal movment make?

when i was thinking about getting an Apeks ATX50 i was told to back away from the DST 1st stage [wich has swivel] and go for a DS4 [without].

Does it really make any differece?

 

[DA Aquamaster]

The anti-swivel argument focuses on an additional o-ring, a potential failure point, etc.

In practice I have never seen a swivel fail in service. But I have seen low pressure hoses fail over time due to being bent into positions requiring excessively tight radius bends in order to obtain better streamlining. In my opinion, a swivel can be a real aid to streamlined hose routing with out requiring excessively tight bends.