Jetstream at low pressure

[buff]

I have a Poseidon Jetstream. Yesterday I breathed a tank down to 0 PSI and low and behold the second stage breathed easier(started free flowing) at lower pressure than higher pressure. I thought the opposite was true with this reg. or am I getting that confused with better breathing at depth?

Thanks for the answer in advance.

 

[scubafanatic]

Hi buff,
.....that's 'normal' behavior for the Jetstream. Once the tank pressure drops to about 300 psi or so, the 2nd stage will begin to freeflow......I'm not a Poseidon tech, but I think it has something to do with the 'condom' in the 2nd stage deflating and letting air vent out.......and I think the exact pressure the freeflow begins to happen (for me at least) starts at about 300 psi.....but it can be a bit lower depending on exactly how the 2nd stage is tuned. I find if I put the " + / - " switch on the 2nd stage in the " - " position I can breathe the reg down to a bit lower tank pressure before it freeflows.

Karl

 

[montyb]

Thats true. Thats why the reg will start to free flow when you crack the tank valve real slow. But as soon as you open the valve all the way and pressure goes above 300 psi the reg quits free flowing.
montyb

 

[rab]

I believe that the Jetstream shares an "upstream" design with the newer Xstream regulators (which I have). When the IP drops too low, there's not enough pressure to seal the 2nd stage piston. This is also the reason that you should only submerge the regulator when pressurized -- otherwise you'll flood the 2nd and 1st stages.

-Rob

 

[montyb]

I checked with Bob3 - he said not so about soaking unless reg is pressurized. Just don't press the purge button

montyb

 

[rescuediver009]

Groundhog is right about the upstream design. This causes the reg's IP to increase and the tank pressure increases. And yes it will freeflow when it gets low enough. This is why you have to setup a jetstream at about 300psi tank supply pressure. High tech stuff.... It shares a similar design to the new xstream. Except for the seat and spring retainer.