Poseidon 3960 IP / Jetstream set-up question.

[redrover31]

Hello

When setting the 123psi IP on a 3960, is it done at a full tank (3-3500psi) or a empty tank (500psi)
If it set 123 at 800 psi, I'm at 112psi at 3000psi on my reg.

When adjusting the Jetstream second, is it done at the low end (112psi) or high end (123psi). Normally I would adjust at the highest IP the second stage sees with a downstream second, but with this design is it reversed?

Thanks in advance

 

[tbone1004]

second stage is an upstream valve, so it needs to be set at the lowest IP the regulator is going to see. I try to set mine as close to 4000psi as I can get since I regularly get cave fills above 3600psi. Set it at max pressure, check it at min pressure.
Since the second stage is an unbalanced upstream valve, the second stage needs to be set at the lowest IP.

This is important because if you set it at 123psi/almost freeflowing at say 3000psi and hook it up to a 3500psi tank, the IP is going to be lower and the reg will freeflow slightly or even all the way depending on when it was set. It will get progressively stiffer as the tank drains *this is not significant to the diver*

The Cyklon being an unbalanced downstream valve needs to be done the opposite way, so the IP of the first stage is set at minimum tank pressure and checked at max pressure. The second stage is adjusted at the minimum pressure and gets progressively easier to breathe as the tank drains *again, this is not terribly noticeable to the diver as the first stages are relatively well balanced*.