My new G250Vs and ramblings

[Couv]

@Open Ocean Diver posted his results above.
Flow test
The greater improvement in dynamic inhalation resistance was with the crescent facing forward (apologies to @couv , with whom I will continue to disagree until we resolve whether this is an airfoil or some other design issue at work). I'll grant you, this was two different regs, but until someone does a side by side comparison changing only the vane, I think this supports the page from the manual also posted earlier about having crescent facing the diaphragm.

Sorry, but Open Ocean Diver's tests were on two different regulators.

I decided to test my only G250V after doing a full rebuild. Thus far, the results don't show any difference in which way the damn crescent is facing.

Here is a quick breakdown of the test.
First with the mouthpiece-got plenty of VIVA with the vane crescent in either direction.
Next with the mouthpiece removed-of course the same results.
Next tried de-tuning the regulator with the adjustment knob. De-tuned until there was no sustained freeflow. Reversed the vane-still no difference. I went up and down with this idea but still no difference. Naturally, due to the nature of the beast there was some inconsistency in trying to duplicate the results.

I had to call it quits when I ran my test tank then my pony too low.

One note that may be of some value to Simon or whoever else if doing this air wasting experiment. If you're using an inline shutoff valve, remove it as it does affect the flow under a very high demand.

If my ears and compressor are up for more testing I will continue later. But for now, I don't see any difference. Hopefully one of you guys will find a more definitive test.

[.... I think this supports the page from the manual also posted earlier about having crescent facing the diaphragm.

Which manual? The G250V manual (that's the the model in question) clearly states and shows the crescent toward the mouthpiece. The posters of the other regulators also show the crescent toward the mouthpiece. The parts manuals all show the crescent toward the mouthpiece.

So there!

 

[Open Ocean Diver]

Removed the inline shutoff, still no help, replaced lever still no free flow. Test tank done and I’m quarantined. Ugh no more fun.

 

[rsingler]

@buddhasummer, you're on your own!

 

[Geo7]

Thanks for the further test, Couv! Wow, the results are surprising.

So the difference in inhalation resistance from 1.3" to 0.3" at 15 SCFM in two different regs with opposing vane orientation did not tell the full story (I though 1" was enough to indicate an effect of vane orientation, but apparently that is not the case).

I like how you adjusted spring pressure with the knob, and then changed the vane orientation. So where does that leave us? The last source of variance is the fit of the lever (not just adjusted lever height)?

 

[lexvil]

Thanks for the further test, Couv! Wow, the results are surprising.

So the difference in inhalation resistance from 1.3" to 0.3" at 15 SCFM in two different regs with opposing vane orientation did not tell the full story (I though 1" was enough to indicate an effect of vane orientation, but apparently that is not the case).

I like how you adjusted spring pressure with the knob, and then changed the vane orientation. So where does that leave us? The last source of variance is the fit of the lever (not just adjusted lever height)?

It leaves me with more modern regulators with finer adjustments

 

[buddhasummer]

@buddhasummer, you're on your own!

Not till I've taken a few more into the maze.

The only time I ever noticed crescent having any effect was when I put a G250HP one into a G250, it worked exactly as HP manual stated.

I'll play Friday until I've wasted my tank then I'll call it quits.

 

[Open Ocean Diver]

Thanks for the further test, Couv! Wow, the results are surprising.

So the difference in inhalation resistance from 1.3" to 0.3" at 15 SCFM in two different regs with opposing vane orientation did not tell the full story (I though 1" was enough to indicate an effect of vane orientation, but apparently that is not the case).

I like how you adjusted spring pressure with the knob, and then changed the vane orientation. So where does that leave us? The last source of variance is the fit of the lever (not just adjusted lever height)?

1) G250VR VFF with the vane in either position, switch in dive mode VFF, in pre dive no VFF.
2) G250VE only way I can get it to VFF is by removing the knob retainer and turn the knob counter clockwise just a bit further passed where the stop would normally be. Orifice is adjusted to just stop it from leaking... cracks at .8” with knob and retainer clip in and fully CCW against the stop.

 

[Geo7]

It leaves me with more modern regulators with finer adjustments

To be honest, that was when I abandoned the G250 for Atomic, but the G250V recently got me tempted...

 

[Couv]

...back from the la-boar-a-tory.
I experimented again with a full tank. G250V hooked up to a MK2 with IP of 135psi, mouthpiece removed. I adjusted the breathing effort knob to several different positions and found that the direction of the crescent on the VIVA vane made zero difference.

@buddhasummer Yes, my G250V has a blue exhaust valve. Just thought I'd throw that out there in case you think your exhaust valve is the culprit.

 

[rsingler]

Just to keep stirring this pot...

If you want to look at the nether edges of this issue regarding the crescent, here are two more things to try (since you are doing all the work, and I'm just kibitzing).
1) get some adjustable first stage, put the crescent toward the mouthpiece, and drop IP until it just barely won't freeflow any more. Then flip the vane and tell us what happens.
Or 2) advance the orifice (drop the lever), disregarding what that does to cracking effort, until a crescent-toward-mouthpiece stops freeflowing. Then flip the vane and tell us what happens.

If flipping the vane doesn't restore freeflow, try the experiment again starting in the other starting vane position.

I like supervising!