LeadTurn_SD
Contributor
Thanks for the replies Herman and Scubafanatic.
Best wishes.
Best wishes.
Mixing and matching
- Thread starter vertigolady
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Ok a little more on the subject of overbalancing. With a little more info provided by rcs9250 (thanks), a little math shows the extra increase in IP of an overbalanced first stage is in the range of 15 psi at 100 ft and 25 psi at 165 ft (rounded numbers). I did a little unscientific testing this after noon with several octos/seconds I have around with interesting results. I set up the seconds (if they were adjustable) to just past a slight freefow with an IP of 125 psi- basically where I set a second stage for primary use, then started to increase the IP until the second stage started to slightly freeflow or 170 psi, whichever came first. Next I set the octos (if adjustable) like the manual suggest- just past freeflow at normal IP (125 in my case) and then a 1/2 turn on the orifice. I chose 125 psi as my starting IP just so I had more range to vary the IP over without going too high. While the absolute pressure values are different, the differential pressures will be the same and they are what is important.
The first reg was a small POS Aqualung, about the worst octo you can have. I set it to just past freeflow and began the test. It started to freeflow at 140 psi or a differential IP of 15 psi. This equates to a 100 ft dive with an overbalanced first stage. With the reg set per the manual (½ turn past stopping FF) , it started to FF at 155 psi or at about 186 ft.
I set my old Sherwood Magnum to just over FF at an IP of 125 and stopped increasing the IP at 170 psi, the equivalent of 280 ft. It never did freeflow. I also checked 2 other old plain Jane Aqualung non-adjustable octos that have been tuned to breath as well as they can, neither freeflowed up to 170 psi . Based on this admittedly unscientific test, I would not worry at all about using pretty much any second stage on an overbalanced first stage, esp if it were set up as an octo .I rarely go past 100 ft and I don't know about you guys but I am really not worried about freeflows at 200+ft....
The first reg was a small POS Aqualung, about the worst octo you can have. I set it to just past freeflow and began the test. It started to freeflow at 140 psi or a differential IP of 15 psi. This equates to a 100 ft dive with an overbalanced first stage. With the reg set per the manual (½ turn past stopping FF) , it started to FF at 155 psi or at about 186 ft.
I set my old Sherwood Magnum to just over FF at an IP of 125 and stopped increasing the IP at 170 psi, the equivalent of 280 ft. It never did freeflow. I also checked 2 other old plain Jane Aqualung non-adjustable octos that have been tuned to breath as well as they can, neither freeflowed up to 170 psi . Based on this admittedly unscientific test, I would not worry at all about using pretty much any second stage on an overbalanced first stage, esp if it were set up as an octo .I rarely go past 100 ft and I don't know about you guys but I am really not worried about freeflows at 200+ft....
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