Scubapro chrome plated brass regulators...

[rsingler]

Is Dean Gafarra the father of the G-250? One of the legendary engineers that went on to co-found Atomic?

That's why it's the G-250...

Letter preceding model number for Scubapro 2nd stages

 

[lexvil]

This is the 1977 patent by Luigi Ferraro co-owned by Spirotechnique and Technisub. The image of the second stage clearly shows the Venturi duct injecting air in the mouthpiece, and the movable vane for controlling the effect: US4192298A - Breathing apparatus with improved regulator particularly for under water use - Google Patents
View attachment 579985

This would make servicing a D400 look like a walk in the park.

 

[axxel57]

And here "the beauty", also received yesterday from @axxel57.
It is really NEW, it is still smelling of vanilla. This fantastic flavour triggered remembrances from the seventies, when I and my wife did buy our MKV sets.
Yesterday she almost cried when we opened the package arriving from Germany and we did smell the vanilla flavour... Who is so old here remembering this flavour coming from Scubapro rubber parts?
View attachment 579942

Me!!

 

[Angelo Farina]

Respectfully, @Angelo Farina, I think you are mistaken. That patent claim relates solely to the first stage, and not the second stage.

From the text of the patent:
"FIG. 3 is a longitudinal section through an embodiment of second-stage valve which has a manual arrangement for adjusting the counteracting flow, once again conforming to the improvement made by the present invention,"

"As has already been stated in the introduction to the present description of the drawings, the other main feature of the invention lies in the possibility which exists of making a direct adjustment, by a manual operation, to the counter-pressure flow in the second stage of the two-stage pressure reducer."

"FIGS. 3, 4 and 5 of the accompanying drawings illustrate a preferred embodiment of valve for the second stage of the reducer. This valve, which has already been mentioned by its general reference 3, continues from a tube 19 for connecting to the flexible hose 4, the considerations applying to this tube being the same as those already set forth as applying to the similar tube belonging to the high pressure valve 2"

So this patent describes two innovations:
- at first stage, the user-controllable IP,
- at second stage, the knob for controlling the Venturi effect.

The VIVA patent is quite different, of course.
But the purpose remains the same, to give the user some control on the Venturi effect, which was not possible in the original "offer regulator" invented by Raimondo Bucher around 1960, nor in Pedersons's patent, which is similar to Bucher's (unpatented), but rotated 90° (probably because there was prior art on the fixed vane in its "natural" position).

 

[Couv]

Kluged together a Venturi vane out of plastic directing air into the mouthpiece results below.

SP 156 static cracking effort .8 H20

Without vane:

CFM, H2O
5 - .9
10 - 1.2
12.5 - 1.9
15 - 2

I got similar results on my flow bench with a Balanced Adjustable rigged up. I don't have enough hands to hold a vacuum cleaner and take pictures all at the same time. Also cannot get picture to save upright. (This way up ---> )

No free flow... pic attached. What do you think should I change the angle or depth?

I thought, surely a well tuned BA would freeflow with the help of the purge button-but no, not unless its slightly immersed in water OR with the addition of a small tube, comme ca:

Just a small tube attached to the mouthpiece shank of a BA creates a venturi assisted freeflow equal to that of a G250.

Re the vane angle of attack. On a G250, max Venturi is achieved when the vane is positioned at a 45 degree angle to the mouthpiece shank. I think the pivot and center-line is also dead center.

Now would be a good time to thank @Overweighted for his help in putting together my flow bench. While I use a few different items, it was his excellent thread with a materials list showing the a control potentiometer and small vacuum pump that allows gnats ass readings for cracking effort while monitoring IP. I still have a few tweaks to make, but it's coming together. Equally, @rsingler for locating the vendors, pieces and parts, and expertise-not to mention his patience while fielding a barrage of questions.

 

[Open Ocean Diver]

I got similar results on my flow bench w a Balanced Adjustable rigged up. I don't have enough hands to hold a vacuum cleaner and take pictures all at the same time. Also cannot get picture to save upright.
View attachment 580003


I thought, surely a well tuned BA would freeflow with the help of the purge button-but no, not unless its slightly immersed in water OR with the addition of a small tube, comme ca:
View attachment 580004
Just a small tube attached to the mouthpiece shank of a BA creates a venturi assisted freeflow equal to that of a G250.

Re the vane angle of attack. On a G250, max Venturi is achieved when the vane is positioned at a 45 degree angle to the mouthpiece shank. I think the pivot and center-line is also dead center.

Now would be a good time to thank @Overweighted for his help in putting together my flow bench. While I use a few different items, it was his excellent thread with a materials list showing the a control potentiometer and small vacuum pump that allows gnats ass readings for cracking effort while monitoring IP. I still have a few tweaks to make, but it's coming together. Equally, @rsingler for locating the vendors, pieces and parts, and expertise-not to mention his patience while fielding a barrage of questions.

Why thank you I really appreciate that it has been a fun journey... love this board, the depth of knowledge from the participants is truly amazing.

 

[Open Ocean Diver]

Just a small tube attached to the mouthpiece shank of a BA creates a venturi assisted freeflow equal to that of a G250.

Can you show me?

 

[Open Ocean Diver]

Just a small tube attached to the mouthpiece shank of a BA creates a venturi assisted freeflow equal to that of a G250.

Can you show me?

I tried still wouldn't free flow.

 

[Couv]

Can you show me?

With a moderate press of the purge button, and a small bit of tubing attached to the mouthpiece shank, this BA will freeflow easily. Hooked up to the rotameter, it slams the indicator disk off the scale.

 

[Open Ocean Diver]

Thanks