Specific Model Mixing Question

[RockPile]

For all you gear experts:

Can I expect any significant reduction in the performance of a Conshelf 21 2nd stage when attached to the 230 bar Titan 1st stage?

I was under the impression that these would mesh well, but one of my LDSs explained that the intermediate pressures would be off too much (which devolved into a pitch but who knows, there could be something to it).

Looking for some input.

Thanks,
JB

 

[rockjock3]

There is this thing called tuning. I would think there would be no problem tuning the IP of the 1st stage as well as tuning the Conshelf properly so that they would work fine together.

It sounds very fishy to me that one 2nd stage wouldn't work with a certain 1st stage. If they can't/won't tune them to work together then I would take my sale somewhere else.

If you kept your sale there I would be cautious that they would purposely tune them, not to hurt your, but so that they would be harder to breath and you might bring them back for the models that they wanted to sell you.

 

[RockPile]

Yeah, that was my concern. I don't want to buy yet another high end reg. I'm starting to gag with every new great regulator release. I'm really jazzed about trying out one of the Conshelfs. Some of the more grizzled divers I know go on and on about them.

Here's my issue with the tuning: I don't want to mess with the 1st stage too much because my primary is a Titan LX Sup. The Conshelf 21 is just in for a bit of a trial as my "octo." My hope is that the differential pressure between the two is not a big enough deal that I have to do anything other then tweak the Conshelf a little.

Thanks for the input Rockjock. What you're saying makes sense and is on par with my suspicions. Do you think this can be achieved without goofing with the 1st stage?

JB

 

[Oceanseleven]

I have a Titan LX Supreme as well and I'm also a certified Aqualung tech. You shouldn't have to do anything to the first stage. All you have to do is have the Conshelf 2nd stage cracking pressure adjusted to where you like it. Most people like it just before free flow occurs. I don't know what your dealer is telling you but it sounds like a lot of smoke and mirrors to me.

 

[knotical]

My books say to adjust the Conshelf 21 for 120-160 psi, and the Titan for 135 with a full cylinder. This should present no problem to the tech. Most Aqualung regs seem to be set around 135 these days.

 

[RockPile]

It sounds like you guys are pretty technically knowledgeable. I'm not going to ask for any super secrets of the trade or anything but while I've got a captive (unless of course you click "back") audience:

Are there any additional concerns, beyond those discussed above, when pairing a piston 2st stage to a diaphragm 1st stage? I only ask because before I decided to go with the Conshelf I briefly considered borrowing my buddy’s older Scubapro reg. No one ever really told me I couldn't match them, I just sort of decided not to take a chance because all the "don't mix brands" talk got me thinking.

Is this a case of just over thinking or is there something to it?

JB

 

[redacted]

A 2nd stage doesn't care whether it is coupled with a piston or diaphram 1st stage. It just wants gas available at about the right intermediate pressure. Only downside I see of mixing compatible stages from different manufacturers is getting service. And many shops will not make that a problem either.

 

[Oceanseleven]

I second what awap said and also, your second stage Conshelf is not a piston second stage. It's a diaphram second stage as are most Aqualung regs.

 

[Mr Carcharodon]

Here's my issue with the tuning: I don't want to mess with the 1st stage too much because my primary is a Titan LX Sup. The Conshelf 21 is just in for a bit of a trial as my "octo." My hope is that the differential pressure between the two is not a big enough deal that I have to do anything other then tweak the Conshelf a little.

JB

The second stage gets "tuned" for the first stage. The first stage is just checked to verify that the intermediate pressure is in the range manufacturer requires. So there is no mucking around with the first stage to worry about.

The tuning of the second stage consists of turning a nut to adjust the compression of a spring. The spring presses on the valve stem and seat. If everything is done right the load exerted by the spring is equal to the IP load on the seat plus the cracking pressure (typically 0.5 to 4 in-water).

First stages are tuned too, but that is to adjust the itermediate pressure. If that it checked, and in spec, there is no need for first stage tuning.

 

[RockPile]

Thanks everyone. This has been enlightening. It's interesting the lies that are propagated in diving.

Thanks,
JB