Conshelf vs Mk5

[ozziworld]

I dive both Conshelf 14s and MK5/109s and enjoy diving then both equally.

Thought about the next decade or so and what others night think about parts availability and maintenance down the road for these two classic regs to be kept in service.

Maintenance wise, I have observed some creep on my MK5/109s sooner than on the Conshelfs. This is measured off the inflator hise with a mini IP gauge.

Any thoughts / inputs would be appreciated.

 

[Eric Sedletzky]

I have both Conshelfs and SP MK5 myself.
For some reason I have never experienced any IP creep in any of my SP 1st's, I don't know why? Not to say they don't for others, just not for me (knock on wood).
I actually use my Conshelf more because it just so happens to have the freshest service, which I do myself on all my regs BTW.
Either one is a piece of cake to service.
I don't think parts will be an issue for either one in my lifetime, especially the Conshelf since there are literally millions of them around and probably as many parts kits. They haven't changed since 1967 and I don't see them changing anytime soon. That alone says something if they are good enough to leave alone that long. If I was forced to choose between one or the other that could be the deciding factor. But then there are sourced kits from other places besides SP for their stuff since they get so weird about DIY servicers.
I also like the design idea behind a diaphragm better than a piston for length of time I can milk out a service interval.

 

[agilis]

Very different designs. The SP is a flow through piston design, the Conshelf is a diaphragm regulator. Each design has its proponents, strengths, and weaknesses.

I prefer the Mk5, but this is mostly because I have almost 50 years of flawless experience with it and can work on it and the 109/156 G250 family effortlessly. I do use an old Conshelf 14 DIN as the reg on my pony bottle. My MK 5s and 10s are mostly DIN, but it's easy to switch back and forth from DIN to yoke.

Parts are always an issue, but VDH carries a good selection, and the used regs themselves are cheap and can be cannibalized if you have not already put aside enough service parts to last several lifetimes.

 

[Luis H]

I started servicing both of those regulators about 45 years ago (1971) while working at a dive shop.

I own quite a few of both. They are both great regulators. I used to prefer the Mk-5 piston first stage for its simplicity, but I now prefer the Conshelf for its durability. I have essentially retired all my Mk-5 first stages.

My favorite single hose regulator is a Conshelf first stage with a 109 second stage.

The newest Aqua Lung first stage still uses the same replacement parts as the 1965 Royal Aqua Master double hose regulator and the Conshelf (that followed it). Parts for the Conshelf will be around as long as Aqua Lung is in business. Your grand-kids will probably be able to service the Conshelf when they inherit it.

The Mk-5 will have replacements parts for a while, but I don’t think they will be around as long and they need service far more often. I have bought Conshelf that have not been service in over 40 years and they were still working fine.

The Conshelf second stage is ridiculously simple and the only part that needs to be replaced occasionally is the seat, which is just a simple hockey puck style rubber seat. The seat are easily made if you can’t find a source, but they are a standard part available from a number of sources.

VDH carries parts for both the Conshelf and the Scubapro Mk-5, but since the Conshelf parts are the same as the Argonaut double hose, the sources for parts is very reliable.

The Scubapro 109 is a bit better performer, but also more complicated. If you keep it unbalanced (with the newer poppet), then the replaceable parts are also basically the same as the Conshelf (a hockey puck rubber disc). A well tuned Conshelf second stage is an amazingly good performing regulator.

I use the second stages from both regulators, but I have retired the Mk-5 for two basic reasons. Parts for the Conshelf are more common (same parts as in my Argonaut double hose first stage) and I gotten to where I don’t like the Mk-5 swivel (the swivel is a personal preference).

Scubapro quit making the replacement stainless steel swivel screws, but VDH has made replacements (Store - Vintage Double Hose). I would replace any of the old brass swivel screws.

By exclusively using the Conshelf first stage, it cuts on the number of spare parts I have to keep in stock.

BTW, most of my dive buddies also use either Conshelf first stage or one of its derivative like the Titan (which is identical inside).

 

[scubafanatic]

I'm kinda rooting for the MK5/109-156 combo myself, as I have stocked up on a few over the last 2 years. I like the classic look of the 109/156 (and the 2nd stage adjustment knob feature) and I like the classic simplicity of the MK5 (plus it's kinda neat there's actually a little piston in there...that's probably a guy thing though.)

 

[Eric Sedletzky]

If I was stuck with one diaphragm and one piston, I would pick the Conshelf and probably a MK2 for the piston - flow-by, only two O-rings, and I don't dive deep enough to need a high performing reg.
For second stages I'd pick 109, 109BA, and a G200B.

 

[ozziworld]

Thank you for all the inputs. Luis, I was thinking exactly that. I like the 109 and I like the Conshelf first stage. I am not a purist by any measure and have no issues combining the two. I kinda like the swivel on the MK5 but it is something I can live without.

 

[agilis]

My first Mk V (to use the original designation) dates to the early seventies. It's a sleek thing with only two LP outputs on the swivel and one HP. I've done hundreds of dives with it. It lived with me in Jamaica for more than a year where its only maintenance was a rinse dive in a fresh water river. It had the old brass swivel bolt, never a problem. I learned to do my own servicing with that regulator and its matching 109. I still have it, in its original configuration. I used it a couple of years ago on a shallow dive, and it was fine.

I have other regulators, but the aesthetics of the Scubapro Mark V, its performance, and my personal connections make it my first choice.

 

[USdiver1]

I own, dive, self-service and greatly respect both the Conshelf (XI, XII, XIV) and the Mk5/R109, however there is one other vintage workhorse that I prefer to both the Connie and SP. AMF MR-12 II, the one with the venturi tube and the bulls-eye purge button. Best damn looking single hose ever made, as well as one of the most reliable and best performing vintage regulators. If you don't have one, get one and see if it doesn't change your perspective on your Connie or SP classic.

 

[george_austin]

I have and use the 14 a lot - love it. I use the Mk5 as well but not as much. I would pick the 14 if I was stuck on a desert island with one single hose regulator. I also like my Voit / AMF MR 12 II -
1. Conshelf 14
2. Mk 5 / 108
3. AMF MR 12 II