Mixing First and Second stages from dif manufacturers

[MT_Shadow]

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" 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)

That is interesting... Yeah I am pretty sure the DiveRite XT1 does not have a overpressure valve on it.

 

[MT_Shadow]

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

Rose
Would the 5$ OPV mentioned fix the issue and make this thing work? I like the idea of the Xstreams but I am not sure I am on board with adding the OPV to avoid the Poseidon 1st stage not having the 5th port and rotation in the turret. Might be better off just getting the apex sidemount set.

 

[Baydoun]

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

since xstreams 2nds are upstream regs, that means they fail closed right? on the appropriate first stage, the OPV allows the first to bleed extra pressure. What happens if a first stage with no OPV has a freeflow from freezing open, and the second stage stops delivering air instead of freeflowing? does the hose explode or something?

 

[lexvil]

since xstreams 2nds are upstream regs, that means they fail closed right? on the appropriate first stage, the OPV allows the first to bleed extra pressure. What happens if a first stage with no OPV has a freeflow from freezing open, and the second stage stops delivering air instead of freeflowing? does the hose explode or something?

Rose is right, you don’t need swivels so just use the Poseidon’s or just the diverite, you can make the cross compatible’s work but why bother …

 

[Baydoun]

Rose is right, you don’t need swivels so just use the Poseidon’s or just the diverite, you can make the cross compatible’s work but why bother …

I'm not the one mixing regs, just genuinely curious about what would happen in the scenario i described.

 

[MT_Shadow]

Rose is right, you don’t need swivels so just use the Poseidon’s or just the diverite, you can make the cross compatible’s work but why bother …

Mostly i was going for hose routing. with the Poseidon you get the left and right hose setup at the 2nd stage but then you have more of a mess at the first stage. With the diverite or apex you get cleaner hoses at the 1st stage but you have to convert the 2nd stage for the right hand hose output. was going for best of both worlds i guess but it is looking more and more that the apex side mount set would work better. no idea if it will breath the same or better but I have read a lot about the xstreams being the cats meow for breathing off of.

 

[MT_Shadow]

I'm not the one mixing regs, just genuinely curious about what would happen in the scenario i described.

I am also interested now Baydoun.... I have never dove a downstream reg I guess. I have learned today. Lets hope someone comes back with the answer and maybe a picture of the splosion.

 

[iointerrupt]

I will admit I always get my upstream and downstream mixed up.

Regardless, I think hose explosion is the most likely failure mode. If the first stage fails catastrophically, and it sends tank pressure out the low pressure port, the next weakest link in the chain is probably the low pressure hose.

 

[MT_Shadow]

I will admit I always get my upstream and downstream mixed up.

Regardless, I think hose explosion is the most likely failure mode. If the first stage fails catastrophically, and it sends tank pressure out the low pressure port, the next weakest link in the chain is probably the low pressure hose.

I guess before adding the OPV to the 1st stage Poseidon had a proprietary hose that had it built into it. The more you know *rainbow shoots across my 1990s TV screen*

 

[MT_Shadow]

From what I am finding the real benefits in breathing are seen at way deeper than I am going to be going and the xtx50 will probably perform better at my depths. Thank you everyone for your replies and education. I will look at getting the xtx50 sidemount setup and just ditch this idea until I am looking at much deeper depths.