new picture with valve 9

[Rotary-Motion]

hi all

is the new GL pic up here with valve v9 on it?

[Tony]

V9 was to do with filling the processor and sight tube at the same time.

I don't have one on my processor as I use an external pump for filling, but I can see why you might want one.

It's not in the original GL design though, which makes me reluctant to suggest that we include it on the GL page.

[Julian]

Diagram with V9 comes under the heading "Subsequent modifications and additions to Graham's design".

Grahams original design didn't even show a sight tube, it's only mentioned as an addition in the text on his site.

[Tony]

Fair point.

I think Graham would've added the sight tube subsequently to the diagram if he was as deft with graphics packages as you Julian

[Julian]

Oh Gee, I'm going all shy now!

Big question is ... would he have added valve V9?

[Tony]

I'm going to be all controversial now and suggest we ask him 

[Julian]

For the sake of adding one valve to make the design far more flexible, I'd guess Yes, but ask away!

[Rotary-Motion]

could i mount this way?

[Julian]

Yes you could.  Personally I prefer to see the venturi above the oil level in the tank.  That way, if you forget to close valves, oil won't find it's way to places it shouldn't be.

Then there's the old chestnut about vertical vs. horizontal mounting of the venturi, there have been several threads on that subject!  With a good venturi, I don't think Grahams original layout will work too well without a jet breaker™.

[Tony]

My first two builds had a horizontal venturi with drilled spray arm in the tank for back pressure.  This worked fine.

Current build has vertical venturi following Jamesrl's advice.  It does suck amazingly well, but it also makes loud slurp - slurp - slurp noises out of the vent when demething, which the horizontal ones didn't.

[Julian]

I get a constant "slurp" from the vent when demething using a horizontal one!

I've offered the theory on the forum a couple of times that it's not so much back pressure as ensuring the pipe down stream of the venturi is "filled" whilst still retaining a good flow.

When I get a chance I want to play around with divergent nozzles in a venturi of preferably and ejector.  If I'm right the venturi could be connected immediately adjacent to the tank and could offer a good spray pattern within.

[Tony]

Now I'm 100% with you there on the filled venturi thing!

The venturi action must only work if the liquid sticks to the sides of the 10 degree cone on the way out.  If the throat velocity is too high I guess it can just "jet" past that.

I think we ask a lot of the venturi to both draw in liquid and also air (adding bubbles to break the surface contact with the 10 degree cone).

[Julian]

I don't think it needs to fill the cone, or at least not all of it.  I drilled the throat of my cast venturi on the lathe so it was exactly concentric and it wouldn't always establish a vacuum when the suction valve was opened.  By putting a jet breaker™ just down stream of the venturi it establishes every time, but I doubt most of the flow from the throat touched the discharge cone.  If it ran all the way down the discharge cone you could speculate that it may "block " the suction port and possibly blow back up the suction line.

I recon that a parallel throat in a venturi is a bad thing (contrary to what has been stated on the forum in the past) and that the transition direct from the 60° inlet to the 10° discharge will offer a diverging nozzle effect.  I need to make another venturi, with no parallel section to the throat and see if it will perform without a jet breaker™.

[Tony]

Certainly the big commercial ones don't have a straight section in the middle, it's cone straight to cone with the side feed at the transition.

[Rotary-Motion]

V4 and V7 can be left open after meth has gone in via venturi if! the venturi is on the top horizontal?

vertically vlaves need to be shut?