My new G250Vs and ramblings

[Open Ocean Diver]

@rsingler et al.

Viva Flow Vane

In the G250V Repair Tutorial video & the G250v service manual, Rene' Dupre' says, "Orient the flow vane so the recess faces the mouthpiece."
View attachment 634245

The S600-G250HP poster clearly shows the same. However, as Dr. Rob points out, the 2003 G250HP Repair Guide has the following statements:

"Maximum VIVA:
Place the new knob and vane assembly
back into the housing with the crescent shaped
notch facing forward toward the
back of the diaphragm for maximum VIVA.

Minimal VIVA:
Place the new knob and vane assembly
back into the housing with the crescent shaped
notch facing forward toward the
mouthpiece opening for minimal VIVA (ie:
for rental equipment). "

The 2003 S600-500 Repair Guide has the same statement & SP Engineering Bulletin #254 has a similar statement.

So which way makes the most sense? I say crescent toward the mouthpiece. The idea of the vane is to direct or block maximum air flow toward the mouthpiece. The larger blade surface should be toward the aspirator.

Could you please pass on... G250V Repair Tutorial video

 

[buddhasummer]

Tested today... Crescent facing diaphragm free flows, crescent facing shank no free flow. Two different G250V though.

Try it in both ?

 

[Couv]

Could you please pass on... G250V Repair Tutorial video

I do not have it, I saw it on a friends computer.

 

[buddhasummer]

Sorry if I missed that detail, but did these have the cutout?

I don't recall, hence asking previous customers to check.

 

[buddhasummer]

Politely disagree, @couv. What you say sounds logical, in terms of "catching the airflow". But for some reason (case design?), it works the other way around. I don't think the manual is mistaken.
In any case, I think Scubapro got out of the habit of teaching max performance, and into "least complaints from occasional divers" regarding freeflow. At a SP seminar three years ago, I'm sad to say that the instructor was completely unaware of the capability of reversing the vane to increase performance. Had to show him that page from the manual.

Can someone with a G250V that freeflows without the mouthpiece compare the two vane positions?

I have one doing just that, I'll reverse flow vane.

 

[buddhasummer]

Thanks for the testing! I am in the same situation with two G250Vs that won't freeflow. Have not taken them diving yet, but they seem to breathe fine on the surface. I agree you can tell if it is safe with experience and if you compare with other regs. No freeflow seems an unusual situation for a Scubapro reg though, so I'd like to fully understand it.

To me the cutout was the obvious big change compared to the classic G250. Perhaps the cutout achieves an intentional reduction in venturi effect (intended for tech divers), and the differences we are seeing are due to the reg being designed to be at the threshold of positive venturi, but tiny discrepancies in tolerances of different parts either cross over or not? Just a guess...

I tried both positions on each non free flowing regs, it made no difference, but that was with the.218 springs.

 

[Couv]

I have one doing just that, I'll reverse flow vane.

If I remember correctly, the vane on a G250V just clicks into/out of place-so experimenting on the same regulator should be....a snap.

 

[buddhasummer]

I know you know what I’m gonna say Simon but I’ll say it anyway; if it cracks easy and will give you all the air you want when you want it without being unstable why care if it won’t free flow?

Just want to know why? My results aren't consistent, why? As you know Lex I'm OCD and it's messing with my head.

 

[Open Ocean Diver]

I do not have it, I saw it on a friends computer.

Bummer

 

[buddhasummer]

Bummer

I do, I'll get it to you. You want it too @couv ?