Vortxrex/jet orifice

[N-Lionberger]

Hey there everyone. I purchased the plans for the Vortxrex dryland dredge off of ebay and have been working away at them. I am just about ready to slap the outer manifold on but just for the sake of my nerves want to make sure i drilled the jets the right size. In the video Dave says 1/4 inch and on a 49ermike webarchive I read he ran the 4" rig with 2 of the old style 1.5x2 keene pumps on BS 8hp or a single 16hp. I have two of those pumps, I figure it should be good but better safe than sorry. I read an older thread about a vortxrex build in which most of the OP questions are missing but gathered that there is some sort of formula to determine jet orifice size based on the pump output, does anyone know?

 

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[seekerGH]

 

[winners58]

its better to start with smaller holes, test, and tune to pumps volume and pressure...

 

[russau]

I don't know the formula BUT if your going to use a 4 inch setup , take the dia. of Keenes 4 inch jet orifice and divide it by the number of ports you plan to use. Id like to see the formula also ! And like it has been said before, the jet orifice dia. is determined by the pumps ability to do the job.

 

[seekerGH]

you will need the curve for the specific pump. Check page 3

https://hethongthietbithuyluc.files.wordpress.com/2012/03/bang-tinh-thuy-luc.pdf

EDIT:

Example pump curve


The 'head' is the pressure in the system. The orifice size will control the backpressure or head. More motor/pump horsepower is required to keep the GPM flowing per the pressure.
When deciding which motors to use, look at the optimum GPM output per the pressure. You dont want your motor lagging nor working too hard for the pressure required.
Pump curves for dual motors is a bit more complex, especially if in series vs parallel, but, head pressure is a constant, and flowrate is controlled by the orifice and the pipe size. (Note that it is not simply divided by 2, as there is only one pipe.)
While 2 motors may seem to work, the pump curves will tell you if they are working at best efficiency, or lagging.
2 motors is 2 times the fuel and 2 times the maintenance.

If you have the 2 pumps, it is easy enough to belt them off of one motor...

 

[polekaat]

Alaska Gold Forum :: Alaska Prospecting Forum :: Dredge: basics of venturi vs Nozzel sizeHere's all you ever wanted to know about venturi calculations.

Polekaat

 

[russau]

Thanks Trevor!

 

[N-Lionberger]

I can't wait for spring time.

 

[russau]

Im assuming that these are a 3 in. and a 4 in. I had one on my 4 inch dredge BUT I sold it due to knee replacement and thought I was done because of it. Now I bought more dredges because I was feeling better and stronger. BUT I may be jumping a little to fast for my own good. And then again I wont know until I get them out for a little fun!! And then make my decision!

 

[N-Lionberger]

They are both in 4", the top one is the forward highbanking nozzle with the air inlet valve and the bottom is the booster jet. I am planning on setting it up on dry land like in his videos. I tried hooking the booster jet up in tub to give it a rough test and it has scary suction. I now want to make another 4" booster and a 2.5" to replace the jet logs on my floating dredges.

 

[russau]

If built correctly , youll really like its performance! Im building a 5 inch device now for a under water dredge.

 

[mpgken]

Ok, just wanted to subscribe to the thread and couldn't find the link.