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Unread 07/09/2010, 05:57 PM   #1
ivanr
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"Excalibur" anular/tangential venturi for orca needlewheel.

I had read an earlier thread which died out some time ago on the idea for an annular venturi.

So I built one and it works great. Better than great.

My setup is a 40" tall skimmer I originally built to run on beckets. Its true head is closer to 36". But when I was out shopping for pumps I decided to try the orca needlewheel , knowing full well I was at the edge of performance.

Using the stock venturi was a bit of a letdown compared to the beckets. But I liked the pump.

The venturi pictured here I built in about 3 hours. And its significantly better than the stock venturi. The inside pipe is 1.5 PVC and fits perfectly inside the 2" PVC threaded pipe feeding the orca pump. The inside pipe protrudes into the pumps housing and is flush with the inside. Which still leaves about ~1/4" gap to the impeller. The inside pipe is drilled into its wall with about 20" holes. My guess is that the water blasts tangentially inside the pump and across the holes, which by the gods of Bernoulli draws air.

I wasn't really expecting it to work but I thought it would be a neat way to feed air from an Alita 40 if it was crap.

Much to my surprise performance is significant increased. By how much i can;t measure. But it could be 50-100%. Now part of this is due to there being little restriction and so the water throughput went way up as well. So much that I had to constrict the input water feed. But with increased flow is more air. Whats the air/water ratio I don't know.

But there you have it. You may still be better of with an Alita for you're situation, but in my case I have maxed out my skimmer, and its about the footprint of a bar fridge.

I know there is another annular venturi out there, but the manufacturer wouldn't sell me one.



Last edited by BlueCorn; 07/09/2010 at 06:17 PM.
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Unread 07/09/2010, 06:06 PM   #2
ivanr
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A better picture.


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Unread 07/09/2010, 06:24 PM   #3
ivanr
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Here's a picture of how to build one.

- take a 2" threaded pipe, and tap it with a 1/2" inlet for the air intake.
- Drill into the wall of a 1.5" pvc pipe. The pipe should nicely slide into the 2".
- Using a router cut half the wall thickness away from the 1.5" pipe. This should expose the holes you drilled earlier. Also router a bit farther along the pipe so that you will create an air gap, or channel to the 1/2 air inlet.
- Slide the two pipes together and glue just before you finish.
in my case I pulled the impeller housing off the orca so as to endure the 1.5" ripe would be flush and market how far it needed to extend.
- You should also dremmel file the back end of the 1.5" inner pipe to smooth water transition.

For what its worth.


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Unread 07/10/2010, 11:37 AM   #4
ivanr
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The original forum link was
http://www.reefcentral.com/forums/sh...ostid=13591049

titled: Annular venturi - "Pimped Beckett" - gathering ideas


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Unread 08/22/2010, 11:27 AM   #5
ivanr
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I guess needlewheel skinners must be going out of fashion based on the interest.

I've been running this new valve for over a month now. Adjusting it now and then to play with performance. So far it is still running way better than the original venturi valve. I'm hoping someone else will try building it to verify.


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Unread 10/27/2012, 09:02 PM   #6
pacmann118
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I am actually in the process of using an orca pump to mod an RK2 skimmer, and am in the same situation, as MRC will not sell an asprirating venturi for their own damned pumps... I'll post up a pic when I am done, it will be similar in design.

Thanks for posting this up, it literally may be the only answer ive found for my problem, after 3 days of searching.


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Unread 10/27/2012, 09:11 PM   #7
pacmann118
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Also, are you still using this design? Did it end up working long term? Any additional info would be greatly appreciated!


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Unread 01/29/2014, 02:38 PM   #8
ivanr
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"Excalibur" anular/tangential venturi for orca needlewheel.

I decided to look up this thread to find out when I built this venturi. And if anyone else had.

In response to the last post I have been running this venturi flawlesssly. I've found that there is one point in the air mixture that the pump goes completely wild and I get an air/water explosion that my 1 1/2 return can't handle.

I am now building an updated version because I got a nice drill press last fathers day and I've decided to make a new version with many more holes. I am hoping to mod the skimmer a bit to handle the sweet spot.


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Unread 01/29/2014, 03:24 PM   #9
ivanr
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One other observation to update. Last year I did finally buy that Alita 40 pond pump that others with the Orca Needlewheel were using on the stock ventturi.

It didn't make any real difference. I found that when I added the air pump all I did was fill the pump with enough air that its stopped working. I did play around with valving down the air flow but after playing around with it for over an hour or so I didn't find that I got a better air mixture on my new venturi from when it was normally aspirated.


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Unread 04/27/2014, 03:15 PM   #10
russeko8
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venturi

Im currently looking to make the same set up could you post some pics of your new design or even some more pics of the old trying to wrap my head around exactly what you did.

Thanks


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Unread 03/19/2021, 05:00 AM   #11
ivanr
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Back when I first built this valve it was a pain to build. And I could only do it by hand for a large valve. which in this case is 1.5 inches wide.

I've been in the hobby since 1985 and probably built 20 performance skimmers in the days when the store ones were crap. I stopped development in 2006 with this as it was way more than I needed. and I'm not a machinist.

But with 3D printers I bet one of you might easily be able to duplicate this and scale it down for another pump. Which coupled with the new DC variable pumps should make this valve very usefull for high capacity skimmers.

Probably around 2015 when I was tuning my skimmer I hit a sweet spot and the output of the valve was so high that it overloaded the skimmer water outlet which was only 1.5 inches. There was a massive air water mixture in the skimmer. Its a BIG skimmer. Beer fridge size. The sound of the reeflo orca pump changed and I'm not kidding but it was akin to a turbo kicking in. But being an AC pump this spot of air mix to input water volume was very hard to find. The next step would have been to re-build the skimmer so it was recirculating with this valve, so I could separate water input.


But I left the hobby soon after due to catastrophic tank failure.

I'm scaling back up now and should be reefkeeping again in a few months. I got covid bored and my kids are now grown. If any of you have a prusa 3d printer out there give it a go. I actually bought an early robo 3d for this that never worked well. And although I rebuilt the print head this past chistmass its still too crappy to spend time developing this venturi . In my case its a new prusa printer or 3 new radions so my 3d aspirations are a while off.

For those of you not familiar with physics principles, putting a venturi on the suck side of the pump is actually a stupid idea. Venturi's really do much better on the pressure side. And the idea for this valve came out of early discussions on this forum around this fact , when needle wheel skimmers started out as foam pads zip tied to pump vanes on this forum.

This venturi I built opened up the throat and there is no venturi.

Instead I re-established the intake water volume, ( like 3 times what was constricted) and that water when it hits the center of the pump vane (or needlewheel in this case) quickly accelerates 90 degrees and washes past all those little holes, which through the miracle of Bernouili cases air to be sucked in after the fact. But in this case the density of water entering the pimp is untouched allowing the pump vane to really get a bite into the water and air only gets mixed a spit second later after the water is accelerated.

As I said in the earlier post when I added a pond pump that others were using to overcome the poor stock venturi performance, pumping air into this new valve did nothing but interfere with the performance.

I was too busty raising kids after I built this thing to do any real performance studies. I can say that the valve ran flawlessly for 12 years. I didn;t even need to clean it. Now writing this I am wondering if the way this valve works I even needed that pinwheel or that it might work better with a regular pressure pump vane. It will be still months before i can try that.

So for any reefers out there with a decent 3d printer and serious 3d cad skills please give it a go.


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Unread 03/19/2021, 06:21 AM   #12
ivanr
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i decided to move this to a new thread , more 3d printer specific.

http://www.reefcentral.com/forums/sh...7#post25722727


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