OP
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My new G250Vs and ramblings
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OP
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Ok, quadruple checked neither would free flow mouthpiece on or off.
Swapped out .218 with a .216 on primary, did nothing else, removed adj knob poppet assy fell out, swapped spring, hooked back up to tank, violent free flow viva on max.
Hmmm.... only a sample of one.
Did the same with back up, replaced with .216 spring and nothing else. Same result, violent free flow viva on max.
Only a sample of two but a little too coincidental to not be the spring.
Now it does have different part number so presumably that's for a reason.
My questions now though are will an A700 free flow given it too uses a .218 spring? Or will but due to different case geometry? And why did SP in later G250Vs change to a .218 spring?
I assume using the .218 stiffer (?) spring lowers Venturi effect, but why did they bother?
An answer, maybe, and more questions.
So it seems it appears logical (?) given spring was the only difference in my sample of multitudes of 10 G250/Vs (using .216 springs and regs behaving as expected) the .218 spring is in fact the "cause".
Admittedly 2 is not a large sample but certainly looks to be the case.
Happy new year everyone.
Take care
Simon
Swapped out .218 with a .216 on primary, did nothing else, removed adj knob poppet assy fell out, swapped spring, hooked back up to tank, violent free flow viva on max.
Hmmm.... only a sample of one.
Did the same with back up, replaced with .216 spring and nothing else. Same result, violent free flow viva on max.
Only a sample of two but a little too coincidental to not be the spring.
Now it does have different part number so presumably that's for a reason.
My questions now though are will an A700 free flow given it too uses a .218 spring? Or will but due to different case geometry? And why did SP in later G250Vs change to a .218 spring?
I assume using the .218 stiffer (?) spring lowers Venturi effect, but why did they bother?
An answer, maybe, and more questions.
So it seems it appears logical (?) given spring was the only difference in my sample of multitudes of 10 G250/Vs (using .216 springs and regs behaving as expected) the .218 spring is in fact the "cause".
Admittedly 2 is not a large sample but certainly looks to be the case.
Happy new year everyone.
Take care
Simon
OP
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I'll sleep a little better tonight.
OP
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I guess in a back up a .218 spring might be a good thing.
Mike1967
Contributor
Please forgive my ignorance but why do you want it to free flow, is it so you know where minimum cracking pressure is?
I also have no idea what a viva is lol
Is it a testing tool?
I also have no idea what a viva is lol
Is it a testing tool?
Freeflow will tell you the regulator has maximum flow capability allowing for finer tuning. Viva is the little turning switch thing on SP regs to divert flow towards the diaphragm to help stop freeflow in use, in general it’s not something you’ll ever notice diving even is you don’t switch is to max flow.
When I had trouble tuning my 108HP above .7 cracking effort, I replace the 216 spring for a 218 and I was able to achieve above .9 effort. My makeshift compression tester showed little difference between the two springs... go figure.
The idea of VIVA (Venturi Initiated Vacuum Assist) is pretty much just that-to reduce work of breathing during inhalation. After the cracking effort of the demand valve is overcome, the flow of air out of the mouthpiece creates a low pressure area inside the case. The higher ambient pressure on the outside of the case acts on the diaphragm. The purpose of the adjustable vane is to create (or as Lex points out, interrupt) laminar flow.
So why do we want it to freeflow? It's part of Scubapro's post tuning test procedure to verify the venturi can overcome the closing force of the demand valve. Another part of the test is to adjust the vane and verify the venturi cannot overcome the closing force of the demand valve.
So why do we want it to freeflow? It's part of Scubapro's post tuning test procedure to verify the venturi can overcome the closing force of the demand valve. Another part of the test is to adjust the vane and verify the venturi cannot overcome the closing force of the demand valve.
OP
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See, gurus, I'm a mere apprentice...
Geo7
Contributor
Happy new year!
I still have a hard time understanding how the venturi intensity can be related to a different spring tension, if the spring/lever assembly can be adjusted to the same cracking pressure? Then the venturi effect should be about case geometry overcoming spring force to depress the lever. It seems regs with slightly elevated cracking effort will still freeflow on max viva, so I am not sure I fully understand...
I still have a hard time understanding how the venturi intensity can be related to a different spring tension, if the spring/lever assembly can be adjusted to the same cracking pressure? Then the venturi effect should be about case geometry overcoming spring force to depress the lever. It seems regs with slightly elevated cracking effort will still freeflow on max viva, so I am not sure I fully understand...
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