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Lndr

Posiedon Regulator

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Poseidon Regs are great they don't use them because they have a upstream ventile and are not fail safe.

The Jetstream is, but not the Cyklon! Dont know about Triton or Xstream. A lot of techies (and wannabes) use Cyklons. The design is well proven and refined during almost 50 years.

 

Upstream means it wont open unless you inhale - regardless of the pressure behind it. How does this make it "not failsafe"?

 

It is a good idea to have a workshop close to where you are. I'm embarrassed to say how rarely I service my Cyklon, but I can say one thing: I never did it because I had to - it never failed me in any way (20 years).

 

/Anders

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What the Tech dive friends of me tell me is, that even if Poseidon Regs are great they don't use them because they have a upstream ventile and are not fail safe. They can block your air supply in case of failure and wont blow like a downstrem ventil will do.

 

They use apeks because of the easy maintainability. They claim that the apeks reg 2. Stages are the only one that can be repaired sucsessfully underwater.

Simon

Simon with great respect; everything you just wrote is completely wrong, and either your friends are misinformed or complete idiots. :D

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I feel I have to jump in, Cybergoldfish. SOME Poseidon regs are upstream, though I don't know whether this applies to the new model under discussion here. To my knowledge, Poseidon is the only manufacturer who still uses upstream designs. (Just to clarify for the unitiated, we're talking about 2nd stages here. Almost all diaphragm 1st stages are upstream, while most piston 1sts are downstream designs.)

 

Apete, "not failsafe" in this context means that if the high-pressure seat on the 1st stage fails, a downstream 2nd will blow open, essentially causing a free-flow, which means that the diver will theoretically still be able to breath off the free-flowing reg and may be able to manage an emergency ascent or get to his buddy or another diver who can donate air before the tank is emptied. When this happens with an upstream first, the IP pressure can just build up, locking the 2nd stage and leaving the diver unable to breath until something blows.

 

That's why downstream 2nd systems include an OPV (over-pressure relief valve) - to keep the IP from going to high in case of a problem or failure with the high pressure seat on the 1st stage. Older Poseidon upstream 2nds have the OPV on the 2nd stage itself, while more recent Poseidon models have the OPV built into the first stage. Without the OPV, even a relatively minor leak across the HP seat in the 1st stage could cause an upsteam 2nd without an OPV to overpressurize to the point that it could explode in the diver's mouth.

 

That said, I think it's fair to say that the likelihood of a castrophic failure like this on a properly-maintained Poseidon that could cause cessation of air delivery is vanishingly low. It's also true that any design of regulator - upstream or downstream - can fail in many ways. Last but not least, getting a blast of 200 bar into one's mouth, as could happen in the case of a HP seat failure on a reg with a downstream 2nd - isn't an ideal situation either.

 

I have great respect for Poseidons. But for me, particularly considering where we live and the locations we dive, the possible problems with servicing are more than reason enough to eliminate the Poseidon as a candidate for our next regs. Poseidons are tricky enough to work on that some Poseidon owners ship their regs back to Sweden for servicing rather than trusting even supposedly qualified local dealers in the US.

 

Poseidons are one of the few regulators that Vance Harlow, in his book Scuba Regulator Maintenance and Repair, strongly recommends that owners not even consider trying to learn to self-service themselves. Even some very experienced regulator techs don't like to deal with them. The company frequently upgrades and revises parts, and servicing a Poseidon requires a number of special tools.

 

I want to be able to do at least minor servicing and repairs myself if I have to - though only if I have to. That more or less dictates that my next reg will be another Scubapro - I've done their reg repair course and already have some of their special tools - or perhaps Apex.

 

Robert Delfs

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Yes, many good points.

The Cyklon is 'Fail Safe' and will freeflow should the HP seat fail. Also, due to the straight-through nature of the design any massive surge in air passes at 90 degrees to the divers airways and out into the water, but it can still be breathed from.

Having used these for 23 years I am comfortable with maintenance, but will always recommend a pro shop over diy to anyone else.

 

The jetstream I would never touch.

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The jetstream I would never touch.

It's the sexiest looking reg ever, though. Once the exclusive choice of cavers here.

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The Cyklon and the Jetstream use the same first stage - a diaphragm upstream design. The Cyklon is a downstream design and the Jetstream is an upstream design with an over-pressure relief valve. If the first stage free flows on either of these, both second stages will still function.

 

The Swedish diving federation keeps a database of accidents and incidents. There is no record of an exploding regulator of any brand. There are plenty incidents with freezing first or second stages - sometimes they freeze open (free flow) some times they freeze closed (no flow). Free flowing is more common, but the "failsafe" theory with downstream second stage valves seems like something you shouldn't always count on. Poseidons are very popular here in Sweden. It would be strange if they were not represented in that database – they are. So is every other brand I could think of. Probably the most common argument for using a Poseidon is that they don’t freeze as often as others. One brand that I don’t see too often (anymore) on dive sites but that seemed frequent in the database was ScubaPro.

 

The Poseidon web site claim that both the Swedish and US Navy/Marine use Jetstream regulators (and I have personally seen South African armed forces using them). I think they’re safe.

 

Regarding regulators with side exhausts: I only know of Poseidon and Oceanic. Oceanic is just not on my list, and if I lived in a part of the world where a specific (any) brand was not represented I would not buy that brand.

 

/Anders

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Well, thanks for all the feedback folks. Decided not to go for the Posiedon simply because i wasn't able to "suck it and see".

 

However, took my new Dacor Vipertek Nitrox 1st and 2nd for their first dives on the weekend and they are great :) Happy to say no change in breathe-ablility down to 35m, dry at every angle (head down, on my back etc) ... everything I wanted :)

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