Why do Poseidon's breathe better?

[ScoobieDooo]

What is it that makes Poseidon's have more of a 'positive pressure' inhalation than other regs?

Both the Cyklon and Jetstream/Odin's are classic downsteam 2nds, correct?

Also, can the above 2 models be used with any other brand 1st stages?

 

[otobmark]

ScoobieDooo once bubbled...
What is it that makes Poseidon's have more of a 'positive pressure' inhalation than other regs?

On the Cyclon, it is the way you set the plastic sleeve around the second stage valve. If you rotate the opening so that it points right at the mouthpiece, you will get an exagerated venturi effect causing the regulator to force air down your throat. If you rotate the piece to face away from the mouthpiece, then you have the opposite effect (hard to breathe). The trick is to find the sweet spot somewhere between. The Cyclon has an unusually high intermediate pressure (170psi I think) The Odin is the normal 135psi or so. I have used the Cyclon w/ another 1st stage and it worked fine. Maybe if I was 500 feet down it would make a difference.
Cheers

 

[The Chairman]

they are upstream regulators and so they are fitted with a pressure release in either the hose or fitted onto a port of the first stage. You must take the SAME precautions whenever you fit one of these to a non-Poseidon first stage.

 

[Scubaroo]

ScoobieDooo once bubbled...
What is it that makes Poseidon's have more of a 'positive pressure' inhalation than other regs?

Both the Cyklon and Jetstream/Odin's are classic downsteam 2nds, correct?

Also, can the above 2 models be used with any other brand 1st stages?

...Vance Harlow's regulator book covers this. I believe you have/had a copy? Look in chapter 1, pages 15/16 for an explanation of servo regulators.

 

[ScoobieDooo]

NetDoc,
You MCSE certified?

Upstream - so if I am correct, in the event of a 'failure' of the 2nd stage, one loses total air flow with not even a free flow during a failure - correct?

 

[ScoobieDooo]

Yup,
Looking at it right now - however, I don't see anyhting in the descriptions of servo valves which would suggest the reason for the 'positive pressure' effect of these regs...

 

[The Chairman]

but yes. The "safety" is in the relief mechanism. It will not allow the pressure to get SO great that you can't breathe on them. You see MOST free flows are NOT caused by the second stage. It is usually caused by an IP creep (not to be confused with an Internet creep) that over powers the downstream valve causing it to free-flow. A downstream reg thus provides an automatic relief valve. BTW, those reliefs are not set the same as the ones usually used for argon bottles.

BTW, if I had one, I would dive it without any qualms. But I prefer how my Micra breathes over all else.

 

[Bob3]

The Cyklon is a downstream, on the Odin/Jetstream the servo is the only part that is upstream. They WILL NOT shut the air off in the event of a first stage puke, they just lose the venturi assist. You can still breathe on the critter, inhalation just gets a tad "harder".

This has been discussed a few times before: http://www.scubaboard.com/showthread.php?s=&threadid=25320&highlight=upstream

 

[brian cooper]

I wholeheartedly agree with Bob3, theCycon IS a DOWNSTREAM
the Jetstream is a servo controlled condom operated 2nd stage. The 1st stages might be up-stream but what 1sts aren't?

Where does this folklore come from?
I've serviced Cyclon 300 right through to Jetstreams, there are basically 4 types of 1st stage and 3 types of 2nd stage then you mix and match.
THEY ARE NOT rocket science but you do have to use the correct proceedure to set them up due to the unbalanced (or at best compensated) diaphragm design BECAUSE the IP goes UP as the supply /tank pressure goes DOWN.
The sleeve in the Cyclon was a secret kept by service techs to keep the customers in the dark and to keep them in business,
1/16" movement can turn a Poseidon from a pussy cat to a lion
PM me if you really need to know more.

Brian C (no charge....)

 

[The Chairman]

"upstream" first stage- that is determined by the second stage. It is an opinion widely held by many, many divers that all Poeseidon second stages are upstream by design. This accounts for the pressure reliefs and why you rarely see them free-flow.

The first stages are suitable for just about any second stage (adjust the IP first). The second stages need to have reliefs with them, in either their hose or on their first stage.