Scubapro gas delivery

[Big Toes]

now, i've read this but am really wondering: scubapro claims that if you mount their second stage into the bottom port of their mk25 reg you'll get approximately 30% more gas flow (this is through their manual). while i realize that this is a balanced piston design; this seems enormous (this is a MK25/S600 setup).

secondly (and this may be more appropriate for the DIR forums) i've also heard that having the same reg in a DIN configuration delivers approximately 150% more gas flow than a regular yoke configuration (this from a dive mag credibility to be confirmed).

soooo... these numbers seem a bit unreal and just wanted to check and see if anybody's got any empirical evidence on this or has tried it. it's apparently a hell of a lot more gas and would be more than willing to change my configuration around if it was true but... any info to the contrary would be greatly appreciated as well as some of this seems a bit far-fetched. and if it's true and you know why i'd really appreciate a good explanation.

thanks for the help.

 

[DA Aquamaster]

The end port statement is true (with a qualification we need to discuss) as the gas comes straight up the piston and directly into the end LP port rather than having to make a 90 degree corner to enter the other ports.

The inlet fitting diameter (internally, inside the retainer) and the filter in use is the same with either DIN or Yoke, so the flow is no different. In both cases the passages in the valve or manifold are smaller and consequently are the limiting factor for flow rate.

That is also the reason why the end port issue is a moot point. The Mk 25 will flow 300 SCFM but the best second stage in the world will only flow 70 SCFM and the best tank valves will not do much more than that and most do a lot less. So in the end, it does not matter in the least where you put ytour primary on a Mk 25, other than for hose routing purposes.

Now, it may be true that a particular reg design may have more flow with a DIN versus yoke connection, but it is by no means true with the Mk 25 nor is it true in general. It should not be the case with any reg if it was properly designed in the first place.

Just curious why you thought this might be more appropriate in the DIR forums?

 

[Fishpie]

The port on the end of the swivel cap is a straight shot for gas coming out of the piston.....I can well believe there is a significant performance advantage. I personally dive with a long hose and use the end port for the 7' hose....not because of the better performance but because it routes the hoses better.
As for the the DIN yoke part I would have to guess that there is no significant difference between the two....if they both use the same filter it would stand to reason that the internal diameter of the DIN tube and yoke nut are the same (at some point where the filter fits) and will flow the same amount of gas.

 

[Big Toes]

thanks for your input; both of you guys much appreciated!

 

[Big Toes]

understood. but if you're pushing 3500 psi through a a yoke or din connection does it make any difference? (um, yes, and i i realize that you should never theoretially do it through a yoke connection).

erik

 

[DA Aquamaster]

No it makes no difference. Yoke regs are commonly used on 3442 psi tanks and the current Sp yoke is if anything over engineered, so I think it would handle 4000 psi without stretching and extruding the o-ring, or at least would not blow up with another 58 psi.