Need a great Poseidon tuner in S.Florida

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dave22387

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Messages
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Location
Coconut Creek, FL
# of dives
1000 - 2499
Hey guys,

I just picked up some used Poseidon 3960s with jetstreams. They're clean and recently serviced but one of the second stages doesn't breath quite as good as the other. Also, the IP is 150 on both (doubles set) and passed the regulator "checklist". Does anyone know a Poseidon "guy" in South Florida who can tune these bad boys up for me. I used to know how 10 years ago or so but it's been a long time since I touched a Poseidon and I remember there is an art to tuning them right. Any suggestions? The subpar second has a slightly higher cracking pressure and slightly lower airflow. I put them both on the same first stage to eliminate that variable. Also, when I turn on the gas the "whoosh" out of the second one isn't as pronounced as the good one. Thanks!
 
Well I'm of no help suggesting a local person to you, but if this request doesn't turn up any good results I'd suggest you mail them out to AirTech Scuba Services in Raleigh... I've used them a few times and they've been great.

PS
Regulator servicing is all AirTech does.
 
Thanks for the input. They are on my radar. I don't think there need a service just a quick tune on the bench and I'd rather not mail them out for a 10 minute tune-up. But if I get nowhere then in the mail they go. Thanks!
 
If you can't find anyone in Broward, and you get desperate enough then you could take them to Bob Henn/Sunshine Scuba in Pinellas. 727-585-0938
 
I'm actually heading to St Pete next week... That may be the ticket
 
Ok, well a couple things...

Your IP is set wrong. For jetstream 2nd stages, it should be set around 128-135. The higher IP is not helping the breathing effort.

The. “Whoosh” is. Sort of a poseidon thing, if you slowly crack open the tank. They behave better with full tank pressure right away, unlike most regs.

“Tuning” your 2nd stages is pretty simple. You just need a 1.5mm Allan key and a bucket of water. I know another poster here used to have a good YouTube video show the technique, but it’s pretty simple.

As long as your IP is stable, you can just dial it down to ~130, then tweak the 2nd stages. ... not hard.

*I will say that if a reg tech set up your Jetstream with an IP of 150, then they are totally ignoring the easily available Poseidon service manuals. It’s just the Cyklon models that are the only ones that use a higher than normal IP, but there is a mythology that seems to persist among many.
 
Thanks for the input. I'm familiar with the whoosh, I was just stating that it isn't as loud and violent as it should be. Maybe that bit of info could help someone on here help me diagnose the issue. I'm gonna lower the IP as the Poseidon manual states it should be lower. As you said it's not a cyklon... Thanks for reminding me about me about the bucket of water thing. I completely forgot about that! It's coming back to me now lol. Tank 400psi submerge about 1in and tune it to freeflow at that depth. I'll try to look up the video to make sure I'm not missing anything. Thanks @Caveeagle
 
@dave22387 couple more things.

@Caveeagle spec on the Xstream and Jetstream is 123, spec on the Cyklon is 165. The Poseidon first stages have IP as an inverse relationship to tank pressure so the IP rises as the tank pressure falls.
Since the Cyklon is a normal downstream valve, you have to adjust the Cyklon with the highest IP which is at the "LP" adjustment of 20bar/300psi into the first stage.
The Jetstream/Xstreams need IP to seat so you need to tune those with the lowest IP that they're going to see which is at the highest pressure that you'll put into them. The manual calls out anywhere between 200-300bar, but you should set them for the pressures that you usually expose them to. For me that means I hook them up to about 4000psi when I tune them because it's not abnormal to have 3800psi in my tanks depending on the fill station and they like to leak a bit if you tune them on the bitter end of what they can be tuned to. This is VERY important btw. If you can't get access to a tank valve hooked up to 3800-4000psi to tune them, you can field tune them by getting as high of pressure as you can and get them tuned where you want. Once they're set, increase the cracking pressure by about .1" and you should be OK.

The video referenced is mine and it follows the "field repair instructions" for the Jetstream and Xstream. I can't attach the PDF on how to do it because it's a copyrighted document, but it is outlined above. With the Jetstreams the "depth" is to get a hissing JUST above the mouthpiece, and on the Xstreams, Poseidon was nice enough to actually put a mark on the body for where the cracking effort "should" be. Now, this will not get the regs accurately tuned. I.e. you won't be able to set them to 0.9" easily which is where I like to put all of mine. This is a field tuning where you can get them all close enough, typically 1.1-1.4" and to get them repeatable you need a magnehelic gauge.
 
Very cool, thanks @tbone1004 . You certainly know your poseidons
 
https://www.shearwater.com/products/swift/

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