Old Scubapro Reg - is it worth upgrading it??

[halocline]

The area between the exhaust diaphram and the cover is very small, so the bubble has to squeeze around that to get to side vents, there was where the resistence hit higher.

That sounds unlikely IMO. It is true that in face down position, on a conventional regulator the exhaust valve is about an inch shallower than the diaphragm, this is what's known as case fault geometry and is the limiting factor on how lightly the reg can be tuned before it starts freeflowing out the exhaust valve. So, if you're tuning a G250 et al as lightly as possible, the exhaust valve will be on the edge of free flow in that position. The D series, with the coaxial valve, has a much smaller depth distance between the diaphragm and the exhaust valve, which means the reg can be tuned more lightly and still be stable. But the only way for that to theoretically increase exhaust work would be if the reg was tuned the same as a G250, say 1.25", and then the exhaust valve would have about the same resistance as the diaphragm. A machine could certainly interpret that as increased resistance in exhalation.

I suspect that, given most normal dive positions, the D series exhaust valve is no lower in relation to a diver's mouth than the exhaust valve on a conventional regulator, which (I'm guessing) would be the determining factor, along with exhaust valve size, for WOB on exhalation. I'm not in a position to ague that ANSI machine tests show a difference, but I can definitely say that WOB, inhaling and exhaling, is not higher on any of my very-well-tuned D series (or air 1s or converted pilot) than on any of my G250s.

 

[axxel57]

Peege, that was more a joke. I wouldn't like to have the bubbles all the time in front of my mask. And you're right, those regs just breath very fine. I have done quite some dives below 300 feet with it and never experienced any problem. Actually, it seems you know something more about this reg than a lot of us, but I never felled anything like hard exhaling. I guess that might be because I never used anything else in my deeper dives, so I cannot compare. Maybe this 'flaw' would only play a role in greater dephts and increased air density.
I have an idea what you could modify, but then I still would have the bubbles in front of my mask .......
Thanks anyway for the infos!

 

[peege]

View attachment g250-d400 wob.pdf

That sounds unlikely IMO. It is true that in face down position, on a conventional regulator the exhaust valve is about an inch shallower than the diaphragm, this is what's known as case fault geometry and is the limiting factor on how lightly the reg can be tuned before it starts freeflowing out the exhaust valve. So, if you're tuning a G250 et al as lightly as possible, the exhaust valve will be on the edge of free flow in that position. The D series, with the coaxial valve, has a much smaller depth distance between the diaphragm and the exhaust valve, which means the reg can be tuned more lightly and still be stable. But the only way for that to theoretically increase exhaust work would be if the reg was tuned the same as a G250, say 1.25", and then the exhaust valve would have about the same resistance as the diaphragm. A machine could certainly interpret that as increased resistance in exhalation.

I suspect that, given most normal dive positions, the D series exhaust valve is no lower in relation to a diver's mouth than the exhaust valve on a conventional regulator, which (I'm guessing) would be the determining factor, along with exhaust valve size, for WOB on exhalation. I'm not in a position to ague that ANSI machine tests show a difference, but I can definitely say that WOB, inhaling and exhaling, is not higher on any of my very-well-tuned D series (or air 1s or converted pilot) than on any of my G250s.

 

[peege]

The modification would not help in the bubbles being in your face, tilting your chin inward is the easier help to that, though not always suggested for deeper diving (you'd want a more open airway than not)

 

[peege]

The work of breathing exhalation measurement has nothing to do with how the the inhalation resistance is set. The G250 inhalation resistance being set to low and then inverted resulting in the free flow is because of the inlet housing design, the venturi flow holes, the inhalation diaphram meeting increased ambient pressure in the inversion, and the spring tension being too light as the air is flowing past the seat. Just because it is coming out of the exhaust valve as normal, is not the measurement of the exhalation resistance.

 

[peege]

If you look at the exhalation diaphram of the Dseries, the expelled gas need to travel through it and then up past the encircled vanes of the diaphram retainer, through then needing to turn 90deg to go through the small gap between the diaphram retainer and the diaphram cover. Then needing to turn again 90deg to travel the length of the diaphram cover, for which to exist through the two opposing diaphram cover vents. The Gseries and Aseries (yes, there will be more), have larger diameter exhaust valves hence more surface area for which the gas to escape from and also much smoothly paths of flows and more quicker exists.

I do really enjoy my D400s and have not noticed a great degree differences of comfort. But if the original poster wwas looking for an opinion of which upgrade would make the larger impact on a chance, going from on the the 1st stage from the MK15 to MK25; or the 2nd stage going from the D400 to an A700 (for example), the second stage upgrade would win the race easily.

 

[NoFe2O3]

Wow - I didn't expect so many erudite responses!! Anyway, my SO decided to spring for all new gear. But it appears that my old stuff has some legs left - so if anyone want to make an offer, please PM me. Best offer gets it. Remember, the first stage is DIN on this set-up.

 

[Couv]

Fishpie, not sure what you mean. Might be just kidding around.
.....

The D series nickname is "Scrotum" because of the shape (I hope.)

 

[redacted]

The D series nickname is "Scrotum" because of the shape (I hope.)

Ever considered a nose job?