Why is a Conshelf so reliable long term?
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Can you expound on the Conshelf hose routing, and what is meant by "normal"? I dive a Conshelf 1st, probably from the '70's, and the hose routing is perfect for single tank setup.
I have one of those old 2nd's just like you described. It's in pristine condition, probably never used. Are there any issues with using that particular model?
How about the 1st stage?
I don't believe the plastic casing of the 2nd stage would have any effect on the performance.
halocline
Contributor
Actually it does, if you consider overall 'feel' as part of performance. The metal case helps put some moisture in the air through condensation, and to me there seems to be a different character to the SP metal case regs when compared to their plastic counterparts. (i.e. 109 vs G250 and converted pilot vs D series) I don't know what exactly is responsible, but the metal regs seem a little smoother. Maybe it's the increased mass of the case, maybe it's the moisture, who knows. What I do know is that breathing a metal case reg for an hour straight just seems to 'feel' better than a plastic reg.
Well, first, the first stage of the Conshelf lives on in the Titan/Legend, essentially unchanged for the most part.
And second, the metal and chrome brass construction is expensive today and only a few premium regulators that are fairly expensive have chromed brass construction that was composed of soldered parts requiring a lot of hand work and fitting. Regulators are not plastic today because it is better, it is because it is cheaper and easier and really no other reason.
So that is why there is no modern all metal Connie, it would not be the mid price high volume leader it was for decades, good value and price point, it would be a high end and low profit margin and therefore low volume item.
N
Personal feeling is impossible to comprehend and understand.
I was working in the dive industry in the early 70s and a letter went around, I clearly recall reading it and it was from USD asking shops to pull them out of service due to the tiny exhaust valve and resulting high WOB. Some did have a slightly larger valve but they did not have the bell or plenum chamber that the "modern" Connie (using modern contextually) has. The exhaust valve of the later Connie is 30mm does not open in water but in a trapped air chamber inside the plenum thus reducing exhaust effort over the tiny exhaust valve wet exhaust of the early Connie.
N
No, not exactly since they have "balanced" second stages and the complication that goes with that and the adjustment knob on the Legend (that always freezes up with sand and salt). And the Legend first is supposedly overbalanced. Though a recent experiment, my wife's Legend with an IP gauge while at depth, saw minimal rise in IP with depth.
The Connie also breaths moist, no cotton mouth.
And since the Connie also does not have the aspirator lever many (including me) set the primary to about .9 and the secondary to around 1.2 or even 1.5 inches/H2O to prevent excessive tendency to free flow.
The Legend and Titan do fine with modern, out of shape, poorly trained divers that pant like a dog but for those who are trained to properly breath and use their (near) full tidal volume any increase in WOB resulting from the slightly higher (if at all) cracking effort is negated. This not directed at any particular person, just my observation of choo-choo train divers.
N
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2airishuman
Contributor
The big difference is that the number and sizes of the ports varies among models. There are some charts out there which help, but some of the later models were made with varying port configurations depending on the year. The XII had only two LP ports and isn't a good candidate for general diving, and it won't accept a DIN adapter, so it's no good for a stage. Use those for a tire inflator or maybe a setup with no BC.
Later versions had 3 or 4 LP ports, with sizes varying and the angular position of the ports also varying somewhat. They are all usable though adapters are necessary in some cases. SPG hoses with a 3/8" end are still readily available which can reduce the need for an adapter.
The other substantive difference is the possible presence of a secondary environmental seal, typically on the "Conshelf Supreme." These seal the spring chamber leaving it filled with a silicone fluid, and in theory reduce the incidence of a frozen spring in cold water, and the potential for corrosion in salt water use. I'm not sure that either of these are a serious problem, but I do have a couple with the environmental seals.
The nut arrangement is something of a nuisance to service. Ordinary wrenches won't fit the available space. Also, it will not accept a DIN adapter.
The recent production ones are expensive, which kind of defeats the purpose. There are all kinds of good regulators out there if you're willing to spend hundreds of dollars for just a first stage.
As Luis noted, the ones with smaller exhaust valves don't breathe as well. I think there are some with full-size exhaust, but with Ts that screw on, these are OK except that you can't get new exhaust Ts for them.
I believe it improves longevity, reduces the likelihood of failure due to impact, and improves resistance to freeflow in cold water.
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