Mixing First and Second stages from dif manufacturers

[MT_Shadow]

I am putting together a sidemount set and the DGX sets include a Poseidon Xstream set but they do not have rotation or 5th on the 1st stage. I was thinking of running them off of DiveRite XT1 din 1st stages. Can I have my LDS tune this setup to work or should I not mix them. I have been running XT2 regs off of them but would like to upgrade the 2nd stages and have the benefit of breathing off either side.

 

[grantctobin]

would like to upgrade the 2nd stages and have the benefit of breathing off either side.

Do you mean switching the second stage from a right hand feed to a left hand feed?

 

[MT_Shadow]

I meant running the Xstreams off of 2 DiveRite XT1 1st stages so that I can run 45degree connectors to get the hoses running down directly toward their respective 1st stages. so left tank hose out of left, right tank hose out of right without having to convert the regulator from left or right like i would have to on a DiveRite 2nd.
And the Xstreams are supposed to breath better I have heard. I have only ever run low end but bullet proof DiveRite 2nds. 0 problems but pretty low end on the breathing effort scale I guess.

 

[MT_Shadow]

Do you mean switching the second stage from a right hand feed to a left hand feed?

sorry I think i missed your meaning in my reply. the Xtreams dont need to be converted they run the same upside down or regular is my understanding

 

[MT_Shadow]

I have found some more info on the tuning and I guess I would just have the LDS tune the 1st stage to the recommended pressures for the xstream 2nds. I have seen reviews that the Poseidon sidemount kits are not great for sidemount but all the complaints are about the 1st stage so I was thinking running a different 1st would fix the downsides.

 

[Baydoun]

from my understanding (which is very little compared to a lot of people on this board) you can mix first and second stages from different manufacturers, but i think, in your specific case, its a little tricky because some Poseidon second stages require higher IP than what the average first stage is usually tuned to. I would take time to really check if they are compatible IP wise.

 

[lexvil]

Mix and match to your hearts content, IP pressure is all the second stage know and they can handle some variation.

 

[iointerrupt]

The Xstream's actually specify a slightly lower intermediate pressure of 123psi. I believe some of the older Poseidons used a higher one. I don't know what the XT's call for, but I assume it's probably the more standard 'about 135psi'.

In the end, I've slapped Xstreams on first stages putting out 140psi and had them work with no problem, so it isn't a showstopper. Tuning the Xstream second stages to whatever pressure the first is running at is also very easy.

That said, the actual issue, is a safety one. Xstream second stages being a "downstream" "upstream" valve design, require some type of overpressure valve on the first stage. Xstream first stages have them built it, but if you are using a different first stage, you have to add one yourself. Cost all of $5: Over-Pressure Relief Valve (User Adjustable)

 

[MT_Shadow]

from my understanding (which is very little compared to a lot of people on this board) you can mix first and second stages from different manufacturers, but i think, in your specific case, its a little tricky because some Poseidon second stages require higher IP than what the average first stage is usually tuned to. I would take time to really check if they are compatible IP wise.

Property 1st stage Setting SI units Setting common units Setting US units P1 30 MPa 300 bar 4351 psi P2 >750 kPa > 7.5 bar >109 psi P3 2 MPa 20 bar 290 psi P4@p1, P4@p3. 800 – 1100 kPa (unadjustable) 840 – 860 kPa (adjustable) 8bar - 11bar (unadjustable) 8.4bar - 8.6bar (adjustable) 116 - 160 psi (unadjustable) 122 - 125 psi (adjustable) P5 >750 kPa > 7.5 bar >109 psi i +/- 110 kPa +/- 1.1 bar +/-16 psi R max 100 kPa max 1 bar max 15 psi Q 0.12 m3 /h 2 L/min 0.07 ft3 /min Internal leaktightness 12 ml/h* * Corresponds to a pressure climb of 0,01 bar/ min for a regulator with a 70 cm hose. Property 2nd stage Setting SI units Setting common units Setting US units CP (cracking pressure) 274 Pa to 392 Pa 28 to 40 mm.w.c 1.1 to 1.6 inch of water
Normal interstage pressure 123 psi

XT1 intermediate pressures recommended at 140psi in service manual

I am not sure having read both haha. I am def not a reg tech.

 

[Rose Robinson]

I am putting together a sidemount set and the DGX sets include a Poseidon Xstream set but they do not have rotation or 5th on the 1st stage. I was thinking of running them off of DiveRite XT1 din 1st stages. Can I have my LDS tune this setup to work or should I not mix them. I have been running XT2 regs off of them but would like to upgrade the 2nd stages and have the benefit of breathing off either side.

MT,

You need to read, know and fully understand the difference between upstream and downstream regulator systems, as well as the requirement for some 1st stage systems to be equipped with an OPV.

Your suggestion is not a compatible mix.

I dive with Xtreme Systems, they should not be mixed with anything.

Rose