mixing first and second stages

[diverrick]

Are there restrictions or standard rules on mixing Second stages with first stages of a different manufacturers? How about within manufacturers? I am seeing lots of regulators out there that have different octo regs from main, and I was wondering if it affects anything operationally. For instance, could Ii use a Scubapro first stage, then attach a Oceanic second stage regulator?

 

[cudachaser]

As long as the first stage intermediate pressures are the same no problem, however there is quite a range on 1st stage intermediate pressures

 

[diverrick]

Thanks Cudachaser. O.K. what if the IP's are different. The reason I am asking, is that I have been seeing Regulator combos on Ebay, with all sorts of mixed regulators, and i was womdering if people aren't just screwing in different parts, to make a full setup. I don't want to buy something thats not right.
Also, how does one go about determining the IP of a particular primary, or secondaary?

 

[Charlie99]

Balanced 2nd stages aren't all that sensitive to the intermediate pressure over the normal range of what's out there, and even with an unbalanced 2nd a simple adjustment of the cracking pressure will suffice.

If you are looking to buy something off of E-bay, you should do the annual service on it before using it. As part of the service, the cracking pressure will be adjusted.

There are a few regs out there, such as some of the Poseidons that have unusually high IPs, but most are in the 130-150psi range --- well within the adjustment range for the 2nd stages.

 

[Diver0001]

diverrick once bubbled...
<snip>

I have been seeing Regulator combos on Ebay, with all sorts of mixed regulators, and i was womdering if people aren't just screwing in different parts, to make a full setup. <snip>

Yep, that's probably it. Screw all the old junk together and dump it off on some unsuspecting slob on Ebay. You really need to treat Ebay like a 2nd rate garage sale and especially when it comes to things like diving gear.

That said, combining different first and second stages can be done but they generally need to be "tuned" to work together on whatever IP the 1st stage can give and the 2nd stage can take. Fortunately there's a big overlap in most cases so tuning isn't generally vrey problematic. Whenever you buy a regulator second hand you should get it serviced and tuned before using it so whatever problems there might be will arise before you get wet (btw, you should add the service/tuning costs to the cost of buying a 2nd hand reg too....what seems like a good deal might not be so good once you get the bill for the overhaul)

R..

 

[nyresq]

I dive poseidon Cyklon second stages on oceanic first stages. the Cyklons are supposed to work on an IP of 175 psi... this is one of the few second stages that aren't specified to operate in the 130-150 range. but even with my IP set at 150, they breathe great, as good or even better than the poseidon first stage set at 175psi.
regulators will have a specification for pressure that is the factory recommended setting. but any where within +/- 5-10psi it should still breathe like a champ.

the only thing to look out for is mixing upstream or down stream second stages. some first stages like the new poseidon jetstreams are made with a OPR valve so if the IP starts to creap and locks up the second stage it won't blow a hose and take your head off......:wacko:


but if you wanted to switch it to a different brand first, you can buy OPR valves that screw into a LP port. these are about $30 and take ten seconds to instal