Din adaper with sp mk10 question

[Seasaw]

I have a scubapro Mk10 / g250 for which I just received a din adapter. To my surprise, a warning card was enclosed stating that when using the din adapter with the Mk10, the cylinder pressure was limited to 3000 psi, vs. 3500 psi with the MK 20. Does anyone know the reason for this limit?

 

[DA Aquamaster]

SP developed the MK 15 (which led to the evolution of the easier to service Mk 20 and the easier to adjust Mk 25) after the patents expired on the MK 10 and the rest of the world started marketing copies.

The MK15/20/25 is beefier than the Mk 10 and one of the design goals was to allow much higher service pressures. I think the original claim was something like 4200 psi.

My thought is that the warning card is included as the HP O-ring in the Mk 10 was not designed for the higher 3500 psi service pressure. Of course it may just be there as a legal disclaimer and/or to promote sales of the Mk 20/25 regs which were designed from the start to be compatible with the higher service pressures.

I don't think there is a big threat of anything dramatically blowing up from the additional 500 psi (actually 200 psi as a lot of yoke equipped Mk 10's have been used regularly with 3300 psi tanks.) but you should check with a scubapro dealer or tech to get the recent thoughts on that subject. Better safe than sorry.

 

[oxyhacker]

Partly because when the MK10 was designed 3000 psi was the standard high tank pressure in use, so that's what it was designed to handle - and partly because when higher pressure tanks became common SP had no particular reason to upgrade the old regs when they could instead sell new ones - by then the 10 was the midline 1st, and SP would be looking for ways to differentiate it from the new Mk20. However, SP has always been good about providing upgrade paths; the fact that they have never provided one for the Mk5 and 10 to handle higher pressures suggests they do not feel they can do so with an acceptable level of reliability though many, many divers run Mk5/10s at 3500 and even higher.

Oh it's interesting to note that in the last years that SP was selling the MK10 as its top line 1st SP was also selling 3300 psi tanks!

Seasaw once bubbled...
I have a scubapro Mk10 / g250 for which I just received a din adapter. To my surprise, a warning card was enclosed stating that when using the din adapter with the Mk10, the cylinder pressure was limited to 3000 psi, vs. 3500 psi with the MK 20. Does anyone know the reason for this limit?

 

[drbill]

This is interesting news to me since I've been diving a DIN Mk10/G250 with HP tanks for quite some time. My other Mk10/G250 is yoke and rated at 3000 psi. I use it on my pony bottle.

I "inherited" the DIN reg from someone who had been diving it with HP tanks for years as well.

This is the same reg I was using when my air delivery system failed inexplicably about 6 weeks ago.

Dr. Bill

 

[DA Aquamaster]

Small correction....When the DIN version of the MK 15 was released, it was advertised with a service pressure of 4350 psi. I am interested in why they are only saying 3500 psi at this point for the Mk 20/25. Maybe it has to do with the rather fragile plastic bushing system they use to contain the HP o-ring and align the piston.

The Mk 10 design is very simple and the HP o-ring is contained in a simple groove in the body of the reg. It is much simpler than the current and rather complicated set of bushings used in the MK 20 and 25. On the Mk 10 there is really nothing mechanically that would fail other than the potential for the o-ring to be too soft to function reliably at the higher service pressure. Although I tend to doubt another 200 psi is going to seriously affect reliability.

I think when SP designed the comparatively large and bulky Mk 15 (compared to the Mk 10) and established the basic body size and design that has carried over to the Mk 20 and 25 that they expected higher service pressures up to 4350 psi to become much more comon than is the case. I don't think the trend to stay with LP steel tanks in the 2640 psi range was anticipated at all. At the time DIN connections were seen as becoming the norm as a means to allow higher service pressures. But today they are quite often used not for higher service pressures but rather for improved relaibility and saftey in overhead situations with LP tanks.

I like the Mk 10 as it is smaller, lighter, more reliable and easier to service than the Mk 20/25 and still offers a very stable IP and far more air than I need. The SPEC kit used for cold water protection is also much better than the TIS kit used on the MK 20/25.

I tried a MK 25 and used it heavily this season but in the end decided the Mk 10 is still a great first stage and offers several advantages over the Mk25, so why carry the extra weight and bulk of the Mk 20 if you don't need it?

 

[oxyhacker]

I was trying to remember when the G250 came out and dug up an '86 catalog and noticed that it rates the MK10 for 3300 psi! That must have been pretty close to when the Mk10 was introduced, they were still selling the amazing Mk7 then, and the catalog describes it as also being upgraded for 3300 psi! Interesting because the last version of the Mk10 in '96 or so, with all the improvements including the the Mk20-style rounded piston was only rated for 3000.

They were also selling both the G250 and the 109 then, interesting (DA will be pleased to note!) to see that they both have exactly the same inhalation numbers, though the exhalation is .4 and .6 with the G250 the better.

Oh hey all you weird SP fans there's a Mk... 6?... 8? whatever, the Mk5 with the pneumatic yoke, on eBay along with a very battered 109, not described (just "old scubapro reg" or something) as such so it'll probably go cheap (if I'd kept my damn mouth shut that is).

Also interesting: the 2003 catalog doesn't give any pressure ratings for any 1sts at all!

Manufacturers seem to backpedal on max pressures a lot. Not sure if its just that they oversell at first, or that once they hit the market weaknesses turn up that factory testing doesn't find - I have an old 3 cylinder Bauer that is rated for 4700 psi, but when I asked a Bauer rep about it he almost had a fit and insisted it shouldn't be used over 3200 psi or so.

 

[Genesis]

on HP tanks (3500 psi service pressure) all the time and have had zero trouble with them.

I prefer them to the Mk20/25s simply because they are much easier to tear down and service, and this promotes keeping them in good condition.

I've not noticed any particular degredation of performance that I can tie to using them at 3500 in terms of HP seat life or any kind of misbehavior.

 

[Seasaw]

Thanks for the replies. Great information. I'm going to go ahead and install the din adapter.
Thanks!

 

[oxyhacker]

Just belatedly occured to me - the 3500psi limitation may well be for the adaptor and not the reg - SP has both short LP and long HP DIN adaptors for their regs, with the idea being that if one uses the right one, one uses the short ones on the older regs and the long ones on the newer. However it's often possible to switch them around and put an LP DIN adaptor on a MK25, or a HP one a MK10 (which is what I usually do just for the extra flexibility). So what that tag may be saying is "if you really want to put this on a Mk20/25 you can, but it will restrict it to 3500psi."

Now if it's the short DIN adaptor why are they saying 3500 pi? There has always been some confusion as to what the actual max rating is for the short DIN adaptor (there may be more than one). SP has at various times referred to the short one as 3000 psi or 232 bar (3500 psi), sometimes on the same page.

DA Aquamaster once bubbled...
I am interested in why they are only saying 3500 psi at this point for the Mk 20/25. Maybe it has to do with the rather fragile plastic bushing system they use to contain the HP o-ring and align the piston.

 

[Kncaffrey]

Sorry to reenergize an old thread like this, but I thought this might be the place to ask...I want to get an adaptor that works for the Mk10 and I can't find a source. There is one on Ebay that says it works for the Mk5 but they aren't sure that it works for the Mk10.

Vance, I checked your book and while it has an exploded view of the older SP one, I cannot put it together in my head to make it look exactly like the one on Ebay. Does anybody have a picture of the one they use? A source? Any help? Thanks fellas!

Kevin