Scubapro A700 with Poseidon Mark III First Stafe

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

OP
WOB0.01J

WOB0.01J

Registered
Messages
28
Reaction score
8
Location
New Hampshire
# of dives
100 - 199
So Lower IP breathe easier and higher IP breathe a little harder. I mean MK III does have a lower IP with the xstream i had earlier in my career which explains why it breathe so easy with the A700.
 

p_kos

Contributor
Messages
479
Reaction score
431
Location
Ontario
# of dives
200 - 499
So Lower IP breathe easier and higher IP breathe a little harder. I mean MK III does have a lower IP with the xstream i had earlier in my career which explains why it breathe so easy with the A700.
Lower IP breaths harder on an unbalanced second. The A700 is balanced so IP changes wouldn’t effect how it breaths. The Xstream second stage can breath very easily but sadly they are often poorly tuned. If you didn’t change the MK lll IP after switching to A700 then the A700 it’s running at the lowest end of the recommended IP range (125 psi) and should be bumped up to 135 for best performance.
 

Jens Bölte

Registered
Messages
24
Reaction score
12
Location
Germany
# of dives
1000 - 2499
Hi,
It does for an unbalanced classic downstream second stage, especially if it’s tuned to a higher IP. If you then paired it with a low IP 1st it would breath harder.
Doesn‘t the valve open against the IP? How is it easier to breathe when it has to overcome the higher IP? Cracking effort should be higher.

Best wishes Jens
 

p_kos

Contributor
Messages
479
Reaction score
431
Location
Ontario
# of dives
200 - 499
Hi,

Doesn‘t the valve open against the IP? How is it easier to breathe when it has to overcome the higher IP? Cracking effort should be higher.

Best wishes Jens
In a classic downstream reg the lever spring force resists the IP pushing seat off orifice. A high enough IP overcomes the spring force. With upstream regs like the jetstream and xstream IP works to seal the valve which is why at very low tank pressures these regs will freeflow.
 
OP
WOB0.01J

WOB0.01J

Registered
Messages
28
Reaction score
8
Location
New Hampshire
# of dives
100 - 199
In a classic downstream reg the lever spring force resists the IP pushing seat off orifice. A high enough IP overcomes the spring force. With upstream regs like the jetstream and xstream IP works to seal the valve which is why at very low tank pressures these regs will freeflow.
The reg set works perfectly as of right now. I will stick to it since there nothing wrong with the system. I will probably tune up the MKIII just a little bit, but as of right now the system takes no effort to get air :)
 

Jens Bölte

Registered
Messages
24
Reaction score
12
Location
Germany
# of dives
1000 - 2499
In a classic downstream reg the lever spring force resists the IP pushing seat off orifice. A high enough IP overcomes the spring force. With upstream regs like the jetstream and xstream IP works to seal the valve which is why at very low tank pressures these regs will freeflow.
So, when you increase the IP in a downstream regulator, it will start to free flow. To counteract the freeflow, you need to increase the spring force, right?

Best wishes Jens
 

p_kos

Contributor
Messages
479
Reaction score
431
Location
Ontario
# of dives
200 - 499
So, when you increase the IP in a downstream regulator, it will start to free flow. To counteract the freeflow, you need to increase the spring force, right?

Best wishes Jens
Yes, or you can lower the first stage IP.
 
https://www.shearwater.com/products/perdix-ai/

Top Bottom