My new G250Vs and ramblings

[Couv]

I ran into a similar quirk today. I just rebuilt and tuned a G200 (unbalanced.) As you know, the case is the same as a standard G250 but of course the demand valve is different. However the flow vane is also the same. I noticed that if the flow vane was positioned all the way to "Max" it would not continue to violently freeflow. However, when the vane was adjusted a hair before "max" then it worked as advertised.

 

[buddhasummer]

Thanks couv, I'll add that to my list of things to check later today.

 

[buddhasummer]

Well now I'm super confused.

Test 1: tank at 210bar.

IP just shy of 140

Primary: .216 spring cracking .9-1"
No mouthpiece violent free flow.

Back up: .216 spring cracking 8-.9"
No mouthpiece violent free flow.


Test 2 after swapping to .218 springs

Primary now cracking at 1.1"
No mouthpiece zero free flow

As per Matt's suggestion, increased IP just shy of 150 still no free flow
Dropped cracking to .9-1" still no free flow
Tried backing off viva a fraction still no free flow

Back up now cracking at .9-1"
IP still just shy of 150
No mouth piece zero free flow
Tried backing off viva a fraction zero free flow

Test 3:

Again using .216 springs again IP still just shy of 150, adjusted cracking to .9-1" and neither would free flow. WTF???

Swapped out to 2 other new .216 springs still no free flow. Set cracking as low as I could get at around .7-.8" still no free flow.

Wondered if in-line adjuster or 70 degree adaptor was having any effect. Put primary onto short hose while testing back up and after a few purges it started to free flow, put it back onto long hose with inline adjuster and swivel and it still free flowed.

Could not get other G250V to free flow no matter how low I got the cracking and on either hose. It felt like it was trying to but could not.

Put them both on my other first stage same result, one would free flow but not the other.

Put G260s onto G250V first stage (both FSR) and even with mouth piece on both G260s free flowed with enough power to loosen teeth.

Prior to swapping back to .216 springs I ensured lever wasn't binding etc.

I'm lost.

Seems something else is going on.

Can someone who bought a G250V off me look into mouth piece opening and see if the flow vane has a crescent or not. I don't think that's it as even when I flipped flow vane crescent facing diaphragm results remained unchanged.

For the gurus, would a lack of violent free negatively affect the performance of the reg?

So lost and confused, open to thoughts and suggestions.

I'm going to dive them this Sunday to see if they "settle" but don't see why that would change anything.

All parts new stock, OEM G250V except exhaust valves. Levers are OEM .141 curly feet levers. Both balance chambers pass "bounce" test, levers not bent/binding/catching. Zero lever play/rattle. Both hold vacuum, no air leaks.

Like I said I built 30-40 of these and never encountered this issue. In fact never have on any G250 variants and I must have done close to around 80 by now, likely more. In fact don't think I've ever had a standard G250 that wouldn't knock your teeth out even with mouthpiece on. As for when I was making the G250Vs I sold I never checked with mouthpiece on so cannot say, they all passed violent free flow test without MP so never even thought to try.

Thank you.
Yours truely,
Stumped

 

[Couv]

For the gurus, would a lack of violent free negatively affect the performance of the reg?

I'm not a guru, but the answer to your question is no. If the cracking effort is within tolerance and when you purge the regulator and get the a good solid flow of air through the mouthpiece then I would not worry about it not venturi freeflowing. That test is basically a substitute for a flow meter. If you've rebuilt 60-80 G250s then you know what a strong purge sounds like (another substitute for a flow meter.)

One reason to do a flow test, either by sound or by using an actual flow meter, is to ensure poppet/orifice separation. In some cases, the cracking effort may be low enough, but, if for instance the lever height is not correct, the hard and soft seat may not have enough separation.

The next step IMHO is to reinstall the springs that were working earlier, put the IP back in the middle range, check that the seats are not engraved and if all of this is good try a new lever.

Not having much experience with the V, I cannot say for sure this applies, but please review this thread:
Scubapro Second Stage Lever Height

 

[buddhasummer]

Thank you sir. Put my mind at ease a little. I really want to know what's going on.

After my initial testing, I did use the same .216 springs that were in them when they were free flowing so was very confused after putting them back in again that neither reg would now free flow. I expected them to FF given they were before trying the .218 springs.

I'll play some more with different springs, but now given I've inconsistent results using same springs I'm wondering what I'm missing.

I'll do as you suggest, but this time mark springs so I know what was what.

Those levers are frighteningly expensive, I'll mess with those as a last result.

Given they are actually performing well within spec guess I should just forget about it but I really want to find out what's going on.

I'll use the current free flowing regs .216 spring in the non free flowing one, but given initially I did use known free flowing springs I'm not sure what that will tell me.

I'll try to be more methodical.

Neither seat has engraved.

Thanks a bunch.

 

[Open Ocean Diver]

Tested my new Simon G260S VFF, then tested two G250V crescent facing diaphragm VFF, 2nd G250V crescent facing mouthpiece no free flow. All three VIVA on Max, IP 138, tested without mouthpiece installed.

 

[lexvil]

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?

 

[Couv]

I agree with the others. If you're happy with the way they breathe & they have a good solid flow call it good.

If you MUST mess with them again: You've already played musical springs-move on to the lever.

In a perfect world, there should be a tiny gap between the lever and the diaphragm disk. It can be done, but it's important to start out with the correct lever height. Have another look at this:

Now that we have a known good lever installed, the cracking effort is where we want it, and the air barrel assembly is installed, guess what? It’s time to do another lever height check. Again?! Yes, but this time it’s even easier. Simply place the diaphragm over the lever and inspect it for fit. The outside edge of the diaphragm should sit in the case with no gaps around the periphery and no wrinkles in the skirt.

If you could see underneath the diaphragm, you would notice the disk is just resting on the lever arms.

I cannot advise you to modify the expensive lever, but...

 

[Open Ocean Diver]

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?

I thought it was a test of Venturi effect?

 

[lexvil]

I thought it was a test of Venturi effect?

It is but if you inhale and get a full rush of air you have all you need, I’ve never met a G that didn’t offer more air than I can use.