Poseidon 2nd stage applications & IP Specs

[Caveeagle]

Just a couple question regarding usage and IP specs for Poseidon 2nd stages. Up til now I have been diving primarily Odin/Jetstream regs in a Hogarthian backmount configuration. I have now added 3 new open water divers to the family and have a trip planned down to south FL in Feb. So I need to put together two additional single tank rigs and don't want to split up my doubles gear.

So.. I have a couple Cyclon 2nd stages, and was considering my options.. I could either put together both sets with Jetstream primaries with the Cyclon backup. Or just use both Cyclons for the same set to keep things matched up.

I had always assumed that you could (or should) not mix/match up a jetstream and Cyclon on the same 1st stage, since the IP Spec is 123(jetstream) and 170(cyclon) psi respectably. This understanding has been challenged by a couple very experienced divers i know that claim you can use them together without issue. I have also seen several used sets for sale with cyclon 2nd stages mated up to other brand 1st stages indicating they are being used successfully with a more 'normal' intermediate pressure <140ish.

So, whats the consensus here from those who deal with Poseidons a lot?

For Bonus points.. Whats the difference between the various Cyclon 2nd stage models? ie: 5000, 500, metal /plastic body etc. Are the internals and tuning and functionality the all the same?

Thanks..

Mark

 

[Bob DBF]

Go to frogkick.dk and get the adjustment specs for the Cyclone. From what I understand, the first is unbalanced and the IP increases as the tank pressure decreases so you don't want the second to free flow as you use the tank. From my limited understanding, the seconds are otherwise interchangeable. I've even set up a Scubapro 109 to use as a second on my Cyclon and they play well together.


Bob

 

[Caveeagle]

Bob, I am working with a couple 2960 and two 3790 1st stages, which should all be balanced regs. I am just dealing with the Cyklon 2nd stages.

I do have the poseidon refrence docs from FrogKick. I am sure I still need to study up some more on that.

From what I can tell, the Cyclon 5000 'package' came with the balanced 1st stage, and the Cyklon 300 came with the smaller unbalanced 1st stage. **somebody correct me if I am wrong.

So if that the case, is it ok to use the Cyklon (hockey puck) style 2nd stage with a lower IP of 123?

 

[runsongas]

yes you can use a jetstream and cyklon together, but they aren't designed to work together. the jetstream is upstream and the IP is utilized to close the servo valve. it runs at 125 psi or so because the cracking effort increases with higher IP. this is reversed from downstream designs like the cyklon.

your choices if you wanted to mix them are to run them at 125 psi (where the jetstream runs well, but the cyklon would have a higher cracking), something in the middle like 145/150 psi (slightly increased cracking on both), or 165/170 psi (cyklon runs well, jetstream harder to use).

the other issue is that if your jetstream hose has an integrated opv, that will limit your IP setting.

the 5000 vs 500 is a balanced vs unbalanced first stage.

 

[Caveeagle]

the other issue is that if your jetstream hose has an integrated opv, that will limit your IP setting.

Thanks for the input. So if I have this right... you don't need a 1st stage OPV on an Cyklon 5000 setup because the 2nd stage has a downstream servo valve that will just free-flow if the IP gets too high. Right?

and.. with an Odin/Jetstream set, you need the poseidon hose (w integrated OPV), or a screw-on OPV mounted on the 1st stage because the upstream valve will not free-flow if the IP goes to high.

 

[Caveeagle]

FYI: I just found this on the Poseidon Web Site...

Q: What Poseidon 2nd stages can I combine with what Poseidon Octopus?
A: You can mix Jetstream and Xstream 2nd stages/octopus on the same 1st stage, as these two 2nd stages work with the same intermediate pressure.
But you can NOT mix a Jetstream or Xstream 2nd stage with a Cyklon 2nd stage/octopus. The reason is that the Cyklon 2nd stage works on a higher intermediate pressure than the Jetstream and Xstream 2nd stages.
Mixing Jetstream/Xstream 2nd stages with a Cyklon 2nd stage can be dangerous!

I know I have seen Cyklon 2nd stages being used both attached to Odin/Jestream as well as other more traditional regs with a lower IP. Can anyone here testify to pro/cons of breathing a Cyklon 2nd stage with the lower IP?

Also I see that the OEM Poseidon Low pressure hose is totally different than the Jetstream hose. It does not look like any type of OPV is integral either. Is that just because of the different downstream design? It will freeflow before it blows the LP hose?

 

[tbone1004]

Thanks for the input. So if I have this right... you don't need a 1st stage OPV on an Cyklon 5000 setup because the 2nd stage has a downstream servo valve that will just free-flow if the IP gets too high. Right?

and.. with an Odin/Jetstream set, you need the poseidon hose (w integrated OPV), or a screw-on OPV mounted on the 1st stage because the upstream valve will not free-flow if the IP goes to high.

Cyklon does not use a servo valve. Cyklon is a "normal" style second stage, works the same way apeks/scubapro etc work. If the IP gets high enough, it will overcome the spring pressure and it will freeflow. Jetstreams/Xstreams will not do that so the OPV is needed. Model differences are different first stages and the only difference in the plastic vs metal cyklons is the plastic or metal body. I prefer metal.

You can mix/match them, but one of them will breathe much worse than it is supposed to. Either the Jetstream having a very high cracking pressure, or the Cyklon having a very high WoB. Put the Cyklons as a set on the 2960 first stages, and the Jetstreams on the 3790's since the OPV is already in there the bottom

 

[Caveeagle]

Cyklon does not use a servo valve. Cyklon is a "normal" style second stage, works the same way apeks/scubapro etc work. If the IP gets high enough, it will overcome the spring pressure and it will freeflow. Jetstreams/Xstreams will not do that so the OPV is needed. Model differences are different first stages and the only difference in the plastic vs metal cyklons is the plastic or metal body. I prefer metal.

You can mix/match them, but one of them will breathe much worse than it is supposed to. Either the Jetstream having a very high cracking pressure, or the Cyklon having a very high WoB. Put the Cyklons as a set on the 2960 first stages, and the Jetstreams on the 3790's since the OPV is already in there the bottom

That make a lot of sense. Right now I have Poseidon hoses on both of my 2960 sets, but when I replace the hoses with adapters, I will either transition over to the 3790 for my doubles/cave rig or install external OPV.

I see the advantage of converting to standard hoses (w/ adapters), but I do kind of like having the OPV right there in your face by the 2nd stage. The only real issue I have ever had with my Poseidon regs what an Over-pressure situation on a nearly new Odin/Jetstream I bought back in '91. I noticed the OPV venting, sort of like a loud PSST noise as I was at the surface doing S-drills at Little River. I did not know what it was doing, so I switched out to another reg. I now know how dangerous that could have become if I had not noticed the OP and it had gotten worse way back in the FL Room. And that was with a nearly new reg, that was checked out etc.

 

[tbone1004]

If you want the OPV in your face, while it isn't cheap, the Omniswivel branded adapters incorporate the hose adapter, a ball swivel, and the standard style OPV into one adapter.
Poseidon Odin/Extreme Conversion Adaptor - Northeast Scuba Supply Store

 

[Caveeagle]

That looks like a nice option