Poseidon Cyklon and Jetstream overhaul...

[Fibonacci]

OK so curiosity got the better of me and I now want to experience the whole Poseidon Adventure...

I've got a cheap used Poseidon 300 with Cyklon coming to practice on before I work up to my goal of an XStream MK3 first with Jetstream seconds...
Been doing a few searches so many thanks to @Bigbella @tbone1004 and @rsingler for their various uploads and technical advice from the SB archives.

I know I need to get a few special tools, and of course service kits and spare parts, but short of getting one of those nifty OEM service control panels, how do you ensure a consistent supply of 20BAR/300psi air to check and adjust the IP?
Keep topping up a near-empty tank or make up some sort of adaptor feed hose via an old non-Poseidon first stage and try to crank it up to deliver 300psi IP off a full tank?

 

[tbone1004]

the 300psi check is not important for the Jetstream/Xstream since they are tuned at the lowest IP that they see which occurs at the highest tank pressure as the first stages are upstream and imperfectly balanced.
The 300psi check is critical on the second stage and the most cost effective way tends to be to modify a welding regulator which is helpful if you have a buddy like @herman to machine an old tank valve but for normal humans you can use different NPT adapters.

Scubatank to 1/4"NPT. This adapter from @DiveGearExpress works fine

DGX Adapter: 1/4 NPT Female to DIN SCUBA Connector w/Bleed

This fitting as a 1/4" NPT Female (aka FNPT) thread form to DIN 477 (aka G 5/8" BSP) thread form connector.

www.divegearexpress.com

Welding regulators usually have 1/4" NPT input, something like this
Connect with a 1/4" adapter of some variety whether it is a hose or a pipe.

tank valve with the dip stick machined out for 1/4" NPT or adapter like this below

Female Din - Made in the USA

john@northeastscubasupply.com

northeastscubasupply.com

 

[Fibonacci]

Aha many thanks for the info…
In Australia the equivalent Argon regulator has a 5/8” BSP bullnose connector which is our heritage standard gas connection... unfortunately different to the G5/8" BSP DIN connector which has the flat face.

https://www.totaltools.com.au/111586-michigan-argon-regulator-55l-min-regarg270?utm_source=google&utm_medium=organic&utm_campaign=shopping&utm_term=MICHIGAN%2055l/min%20Argon%20Regulator%20Twin%20Gauge%20REGARG270&gclid=EAIaIQobChMIpebg5YHH-AIVyZ1LBR2RtAHqEAQYASABEgIZxPD_BwE

Looks like I need to import one with a US 1/4” NPT connector…

 

[Fibonacci]

OK my two Poseidon reg sets arrived yesterday... a 3950 with twin Cyklon second stages (one metal one plastic) and a 3960 with a single Jetstream second stage. Both have the OPV built in, so must be fairly late production.
The 3960 reg set is virtually as-new as far as I can see but the 3950 while sound is well used and definitely needs a service.

Stripping down the Cyklon second stages reveals one in excellent internal condition and one with a little white corrosion that cleaned up well in 50:50 white vinegar and a stint in the ultasonic cleaner with Simple Green Crystal 1:20. So far so good...
However...
Part #8 2429 Valve Piston: one shows a little linear free play between the 'ball and socket' that I guess could lead to a small lag in response for each breath cycle as the LP seal unseats.
Just wondering how much play is acceptable before the part needs to be replaced?

 

[tbone1004]

the slow is usually taken out by the diaphragm when it's in your mouth but that's a pretty cheap part if I remember correctly if you want to replace it it wouldn't hurt. I'm not sure I've ever tried to measure tolerances for that. @rsingler any insight?

 

[rsingler]

It's a fairly tightly formed joint. Any linear displacement more than say, 0.3 mm would suggest that the pivot joint got "overtilted" during a removal, and I'd replace the part (PN 1151). But there's no spec that I'm aware of.
Min Authorized Price is $65, tho' a few places might offer it for less...

 

[Fibonacci]

@rsingler thanks, freeplay is right on 0.3mm... but at US$65 or A$93.56 I will reassemble and see how it goes!
A higher priority now is to replace the 3950's OPV, while the rest of the first stage seems to be in pretty good nick the OPV port vent plug was stuck fast by white crusty deposits.

The 4mm internal Allen key promptly rounded off and the vent plug refused to budge via all the usual methods of persuasion!
Grrrr....

A T27 Torx bit tapped into the mangled 4mm recess bit just enough and it came straight out, leaving the Valve Piston and seal locked in the bottom of the recess by corrosion deposits. Soaking in a hot Citric acid bath loosened it enough for an air gun to pop it out.
Seat area cleaned up fine with some Bronze Wool. Stainless spring was OK.

Seems these OPV's are a natural place for salt water to pool and not get sufficiently flushed out?
Mental note to check after every dive...

 

[tmassey]

I’m going to risk a slight thread hijack:

One thing that has always bothered me about those integrated OPV’s is the inability to test them. With the old hose OPV’s, all you have to do is yank and test that they work. But how am I supposed to test that those OPV’s on the first stage are actually going to do their job in an emergency?

Does anyone have any suggestions? Because @Fibonacci just pushed that from a theoretical concern to very much an actual concern for me.

Sorry for the hijack: I’m following your progress with interest, because I just acquired a set of Jetstreams as well as a set of Cyklons along with Xstream MK3 first stages and I’m about to embark on the same journey.

 

[Fibonacci]

Not really a hijack, you raise a very valid point... the OPV on my 3950 was locked solid by corrosion, and could never function.

The built-in (and adjustable) OPV on a Nemrod Snark III double hose reg can be tested to blow off during setup of the IP, which is then adjusted back down to specs.
Not sure if Poseidon regs can be tested in the same way?
The XStream Deep specs say:
Built in OPV with a release pressure of
232 - 304 PSI (16 - 21 Bar)

 

[rsingler]

freeplay is right on 0.3mm... but at US$65 or A$93.56 I will reassemble and see how it goes!

Well you know, I replied a little too quickly.
No matter how much play there is, the lever action of the mechanism isn't pulling the seat off the orifice. The mechanism is holding it closed, so that ball will be plastered up against the socket no matter how loose it is. There will be no lag in valve opening.
That said, if it's really sloppy, it could present a concentricity problem where the seat doesn't reseal in exactly the same place, and it might be more prone to dribble.

The OPV does corrode pretty quickly. It needs a good flushing. But barring huge salt crystals that physically prevent the spring from compressing, it's pretty foolproof. As for popoff pressure, it's not really like a stage reg OPV. It's more like a "just before your hose ruptures" relief valve, and I don't worry too much about precisely where it releases. There's lots of room between 145 and 400 psi.
@Fibonacci , I'll spot you an OPV housing if you'll send an address.