Upstream Valve Concern

CoalBoy · Jul 25, 2006

Hi eveybody!
I recently registered for membership on this message board.

I would like to solicit input from some of you regarding my concern over using upstream valve regulators. Is there really a cause for concern?

i've been reading articles on the net about upstream regs failing closed as compared to downstream regs w/c freeflow when they fail. has anybody experienced an upstream valve failure?

I use a poseidon cyklon 1st stage and cyklon/jetstream combo for my 2nd stages.

thanks in advance! dive safe!

padiscubapro · Jul 25, 2006

CoalBoy:
Hi eveybody!
I recently registered for membership on this message board.

I would like to solicit input from some of you regarding my concern over using upstream valve regulators. Is there really a cause for concern?

i've been reading articles on the net about upstream regs failing closed as compared to downstream regs w/c freeflow when they fail. has anybody experienced an upstream valve failure?

I use a poseidon cyklon 1st stage and cyklon/jetstream combo for my 2nd stages.

thanks in advance! dive safe!

Contrary to popular opinion the upstream poseidons DO NOT fail closed.. the Upstream designs have an OPV which limits the IP to about 16bar, at this point the cracking pressure is a bit higher than normal, but otherwise they still breathe normally, unlike in downstream designs that freeflow.. Any excess pressure will just vent via the OPV..

Jetstream/Xtreme are upstream designs, but if I remember correctly the cyclon is a downstream design..

CoalBoy · Jul 25, 2006

thanks for the input, 'padiscubapro'.
yes, that's right. the jestream is up- while the cyclon is down-stream.

that's why i "initially" got different 2nd stages. i don't want both to either be freeflowing or running the risk of a 'closed' failure.

the only thing i did is that i tuned down the cyklon, to resist freeflow (kinda tight though), i wear it bungeed to my neck. no prob with the jetstream 'coz it has the +/- switch.

well, freeflow is usually a managable problem anyway, the one that worries me is the loss of gas supply. but as you pointed out, they "DO NOT fail closed..."

thanks!

Bob3 · Aug 2, 2006

Yep, the "fail closed" thing pretty much resides in the realm of Urban Legends, it's usually parroted by "virtual divers" that don't know any better.
BTW; putting a Cyklon on a 1st stage set up for a Jet actually IS like "detuning" it because of the difference in IPs.

Nemrod · Aug 2, 2006

The regulators in question are not the old classsic upstream type valve. Your worries are for naught. I would explain it to you but I got to go. N

DA Aquamaster · Aug 2, 2006

The only serious issue with a modern upstream second stage is the inability for excess pressure from a failed HP seat to be vented by the second stage. But Poseiden has it covered as they incorporate an over pressure relief valve into the LP hose.

The only way it gets ugly is if you use an aftermarket hose with no OPV and at the same time do not install an OPV on one of the other first stage LP ports and/or use a downstream second stage as an octo. If there is no way for excess pressure to vent it would be possible to burst an LP hose on the reg.

CoalBoy · Aug 2, 2006

nemrod,
feel free to explain to me your concept, when you have the time.
i would welcome all the input i can get.
thanks!

CoalBoy · Aug 2, 2006

bob3, you're right.
i think that's why the cyclon feels a little tight. the 1st stage came with the cyclon, but i had it set to a lower IP for the jet, w/c i use as primary.

as i see it, there's no difference between the 1st stage that goes with either the cyclon or jetstream. the only diff is the engraved model name and the preset IP.

:thinkingo

Ed Palma · Aug 2, 2006

Regarding what DA said, that's more more less the same sentiment NetDoc expressed in an earlier thread regarding "Franken-Regs". Here's the link:

http://www.scubaboard.com/showthread.php?t=2980&page=2&highlight=mixing+brands

So from the way I undersstood it, you'll be okay as long as you use continue to use the Poseidon 1st stage with OPV, but if you swapped it out with a regulator without an OPV, then yeah, you could burst a hose just like DA says.

CoalBoy · Aug 2, 2006

About the hoses, are we talking about "explosive" hose rupture?
My concern is that i extended the hose that came with the jetstream(~4ft) using a diverite hose(~3 ft) and coupling.

If the OPV came integrated in the poseidon hoses, then in case of HP failure, the rupture will be on the "poseidon" side, and not the DR side, right? This concern is for diving doubles.

No worries when diving singles, as i use the (long hose) Jetstream and the downstream(Cyklon) as backup, which will act as as OPV, in case.

Upstream Valve Concern

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