1st & 2nd stage

[gene02]

Hi guys I am still new to mixing and matching equipment my have a question I have a US divers 1st stage and am picking up a used Mares 2nd my thought is they should work just fine together. But again I don't know enough to be sure. So what is your thoughts?

 

[wunat]

As long as the IP is being adjusted properly, they should work just fine.

 

[Jorgy]

Properly adjusted they will work together...........

The key will be finding someone who can do the annual service on both brands of stages..........

That will prevent you from having to break the reg apart each time for service.......

Hope this helps..........M

 

[gene02]

As long as the IP is being adjusted properly, they should work just fine.

I am assuming that IP= internal pressure and adjusted properly Hmm!!! not sure bout that one maybe terminology here. I think what you are telling me is that stage1 can only have a out put of ?psi whatever stage2 requires. is this correct?
And if that is the case the US Divers stage2 must also match that same PSI# is that correct?

 

[Jorgy]

Most second stages are designed to work around 140 to 150 psi.........

So as long as the first stage is in that range and I would guess with 99.99% confidence that the US Divers is in that range......

There are some regs that operate at about 160 to 170 psi..........

M

 

[ZzzKing]

IP = Intermediate Pressure but you get the idea.

 

[herman]

I am assuming that IP= internal pressure and adjusted properly Hmm!!! not sure bout that one maybe terminology here. I think what you are telling me is that stage1 can only have a out put of ?psi whatever stage2 requires. is this correct?
And if that is the case the US Divers stage2 must also match that same PSI# is that correct?

Close, IP= Intermediate pressure. IP is the pressure the first stage reduces the tank pressure to and then delivers it to your second stage.
With a few exceptions, all modern regs use an IP between 130 and 150psi, most are around 135 but the exact value is not really that important. A second stage could care less who made the first stage as long as it is supplying an acceptable volume of air at the correct IP. The key here is IF your second stage is an unbalanced type, it will need to be adjusted to get the best performance out of it or it may freeflow, depending on what the IP it was tuned for....and tuning is basically the minor adjustments a tech does after rebuild. If it's a balanced second stage, you are good to go as is because the balancing section of the reg will handle any slight changes in IP as long as you are not swapping amoung one of the few that use different IP values (AL and Mares are both in the 135-145 range). At worst you might have to have a first and/or second stage tweeked a little but otherwise it's not a big deal. If you are having a shop do your repair work, it would be to your advantage to use one shop for all your regs and have a talk with the tech. Have him set all your regs to 1 IP value, that way you can swap between all your first and second stages as you like. I would also suggest you get an IP gauge and check for yourself to make sure they are all set alike.

 

[Tassie_Rohan]

Nope.

Mares regs use a 1/2" diameter fitting for the primary regulator, and their first stages typically have one 1/2" and three 3/8" LP ports.

Check the US diver first stage and see - I suspect it will have only 3/8" LP ports.

If so you will either need to change the hose: which is very easy to do, or order a 1/2" female to 3/8" male adaptor. If you change the hose just make sure you have the correct spanners to avoid scratching the finish, and tighten only a little bit past hand tight.

If the service monkey at the local dive shop baulks at doing a hybrid reg, then take your business to a decent operation that won't mind.

Cheers,
Rohan.

 

[tfsails]

ALL of the advice here is good advice. Regulators are dumb; they don't know who made them nor who made their other stage. Hence they don't care a whit as long as the IP is correct for the second stage. The BS about having to have the same brand for both stages is just that--BS.

I would take slight exception with Herman about balanced vs. unbalanced second stages. Both need to be tuned properly to the IP. I think Herman is confusing "balanced" (unaffected by diver depth) with "adjustable" second stages where minor free flows can be tweaked out by the user by turning the adjustment knob clockwise a tad.

Theoretically, an unbalanced second stage becomes harder to breathe on at deeper depths while a balanced second stage keeps its cracking pressure the same regardless of depth. In the real world, a lot of people have stated that they can't tell any difference with an unbalanced second stage. My own experience is limited to a balanced second so I can't personally attest either way.

 

[herman]

........................
I would take slight exception with Herman about balanced vs. unbalanced second stages. Both need to be tuned properly to the IP. I think Herman is confusing "balanced" (unaffected by diver depth) with "adjustable" second stages where minor free flows can be tweaked out by the user by turning the adjustment knob clockwise a tad.

Theoretically, an unbalanced second stage becomes harder to breathe on at deeper depths while a balanced second stage keeps its cracking pressure the same regardless of depth. In the real world, a lot of people have stated that they can't tell any difference with an unbalanced second stage. My own experience is limited to a balanced second so I can't personally attest either way.

I'm not confusing balanced with adjustable. User adjustable or not, by its very design a balanced second stage is unaffected by varying IP, within reason. The whole purpose of balancing a second stage is to ensure the second stage breathes the same as IP changes, as it (IP) would when used with an unbalanced first stage. On the other hand, an unbalanced second stage when used with an unbalanced first stage will change its breathing charistics as tank pressure (and therefore IP) changes. If you use an unbalanced second stage with a balanced first stage, the breathing resistance of the second stage will not change with changing tank pressure because the IP will not vary.....assuming the balancing portions of the first stage are doing their job. Ignoring breathing resistance changes due to air density at depth, for a given tank pressure a reg should breath the same regardless of depth.