Why is larger better?

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Why is larger better?

Post  pbracer on Tue Apr 21, 2009 7:33 am

What is the principal behind having a larger diameter alignment chamber (air/filter/air/straws/air). I have seen discussions about 4" and 8". I am using 4" with moderate success and reasonable "throw" approx 12'. I have not produced a proper output ring as of yet but I'm thinking that is my last requirement to get a near perfect flow.

In my mind I am having trouble reconciling that the input port is 1"-1.5" and the chamber is 4"-8" and then output is 0.5". As long as the "alignment chamber" is sufficiently larger than the input and output, can't a laminar flow be produced, maybe it needs to be longer if it is narrower, but why wouldn't that have an equally good result?

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Re: Why is larger better?

Post  liteglow on Tue Apr 21, 2009 8:16 am

Hi there.. (still dont know where you from, and your name) Wink

I`m not any expert, but I can try to explain what i "think" the reason is to go BIG !

Water flow at one speed, and when the water have allot of speed, you have a bigger change to get more turbulence!
And no matter how long your pipe is, the speed will be the same all the way up to the output (you understand that?)..

So when the pipe is 8" (or bigger) .. the water will still have the same power, but it will have more "space" inside the nozzle to flow in..
And then it will move slower up, because of the big size Smile

I dont know if this is 100% correct..
But that is anyway my theory Wink


And btw: I did try 4" first, and the result is "ok" on very short distance..
But when I did try 8-10" in diameter , the result is 100% SMOOOTH Very Happy

So I dont recommend any to use 4" !!
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Re: Why is larger better?

Post  John on Tue Apr 21, 2009 8:46 am

I too started with a 4" nozzle. I thought that I could scale everything down. I scaled down the pipe diameter, the straw diameter, and most other things. The things that I didn't scale down were the output, nor did I think that I was probably scaling down the "throw" at the same time.

Like, Filip's, my 4" would work very well under low flow rates (thus a low throw). When I tried getting a larger throw it would start to break up at the end. I believe that has to do with what Filip/liteglow explain earlier.

You want the water to be moving as slow as possible. The length of the tube has to do with it, yes, but also the diameter of the tube is important.

As always you must define your goal before you start your project. If you just want a small throw, then maybe a 4" will be good enough for you, but don't expect it to throw very far. Maybe you will have better luck with the 4", like I said, I built a 4 inch and it worked great, but it didn't throw far enough for me.

Magic built a 6" (I think), I have an 8" and I believe Filip does too.
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Re: Why is larger better?

Post  gryphern on Sat May 16, 2009 2:44 pm

I was playing with nozzles of different sizes trying to see how small I could scale my nozzles before the flow fell apart, and I was able to get an OK flow from inch PVC that was 10" long, but it decayed quickly into turbulence.

So ho the heck does Kohler do it for their faucets with just a nozzle and no chamber? Or will the stream only remain laminar for the few inches it takes to go into the sink? Kohler puts out very detailed diagrams of the internal dimensions of the nozzles:

Bath and sink nozzle PDF

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Re: Why is larger better?

Post  liteglow on Sat May 16, 2009 2:52 pm

gryphern wrote:I was playing with nozzles of different sizes trying to see how small I could scale my nozzles before the flow fell apart, and I was able to get an OK flow from inch PVC that was 10" long, but it decayed quickly into turbulence.

So ho the heck does Kohler do it for their faucets with just a nozzle and no chamber? Or will the stream only remain laminar for the few inches it takes to go into the sink? Kohler puts out very detailed diagrams of the internal dimensions of the nozzles:

Bath and sink nozzle PDF

I think the reason for they have so nice laminar is the small size !
Short distance for the water to hit the end, and the pressure is very small..

I think it should be no problem to make a laminar flow that is only falling down a short distance :-)
I just need to use filter ..
here is a picture how easy it is to make a small laminar flow:



Almost like this ? :

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