Eductors. How well do they really work?

gregt

gregt

Premium Member
To compare the effects of eductors, I did some side by side testing of a 3/4" full sized-eductor, a 1" penductor and the same exact plumbing with no eductor at all.

All tests were on a closed loop with 1" plumbing and a GEN-X PCX-100 pump.

The air injection tests were done by inserting an air pump hose into the closed loop intake. Using this method should provide a fairly constant and equal amount of air for each test. Each film is started with the water pump running and the air pump off. Then the air pump is turned on and left on for the duration of the film.

Here are the results with commentary at the end....

Washer flow tests:
All tests performed 3.5 feet from plumbing exit: (click on image to see short movie)

No eductor


Eductor


Penductor
 
The second test was the air test. (Click on the images to see the films)

No Eductor


Eductor


Penductor
 
Conclusions:

It's quite clear that either eductor is a significant improvement over no eductor. The most telling piece of evidence is the bottom left corner of the tank is clearly not being disturbed by the non-eductor plumbing. This would result in a clear dead spot where detritus would collect.

The differences between the two eductors is less clear by looking at the images. However, in real life there was a significant, though small difference. The penductor did not perform quite as well as the eductor, but it was close. The eductor clearly created more energy in the tank.

While both the eductor and penductor pushed the washer higher, the eductor provided a much more turbulent and wider stream. Difficult to show in a short film, although it can be seen if you look closely.
 
Another observation I made was that the penductor outlet hole is much more restricted than the eductor, despite the fact that it was a 1" inlet and the eductor was a 3/4" inlet. This resulted in more back pressure on the pump. This would translate to less performance on lower pressure pumps than the eductor. Therefore, if you don't have a high pressure pump, I would avoid the penductor. Otherwise, it's smaller size definitely makes it an attractive alternative.
 
where can i get educators or penductor?? i noticed my 3/4 inch pipe just does nothing for flow comming from myt closed loop and was wondering how to step it up, where can i buy these???
 
Black71gp said:
where can i get educators or penductor?? i noticed my 3/4 inch pipe just does nothing for flow comming from myt closed loop and was wondering how to step it up, where can i buy these???
Click to expand...

My eductor came from ecoaquatics.com my LFS "Fish and Other Ichthy Things" loaned me the penductor for the test. (Thanks John) I'm not sure where you can get them from.
 
Eductors from AES

Thanks for making the effort, Greg. It sounds like you didn't need to generate the >10 psi back-pressure on your pump to make yours work, like the manufacturer recommends? It looks like if I tried this with my little tank and an Iwaki 40RLT the majority of my sandbed might end up in the sump!
 
not to be dense,
but, does anyone have any ideas on how say the 3/4 eductor would work on a smaller pump like a mag 9.5? I have a 125 and do not want to blow the glass panel off the other side. Or is this eductor thing only really work in larger tanks? I just hate powerheads but love lots of water movement. does anyone want to loan me one so i can see=)
tren
 
I don't believe it would work well at all. Eductors require high pressure pumps, which a mag 9.5 would not fit into that category. It's most likely you would have reduced flow with that pump.
 
Greg put it well ... that while you might be `gaining' water flow through the loss in pressure [created by eductor] ... but it's less overall flow from the pump than without.

On a pressure-rated pump ... you have the pressure to lose [check out the flow curves ... where a bump of 5' head on a pressure pump normally isn't that big a deal ... where on a flow pump the curve is much steeper [more loss].
 
Greg, any idea if you can cut down the 'bell' portion of the eductor without losing too much performance or making the output less dispersed?
 
I don't know too much about them, but from what I read, they're a nozzle that reduces the diameter of the stream of water. Reducing the diameter increases the velocity of the water coming out (and puts back pressure on your pump). That will increase mixing by making the water shoot much farther. But the eductor takes it a step farther. They have an diffuser around the nozzle outlet. The narrow stream of water shooting through causes a localized low pressure zone in the diffuser. Low pressure in the diffuser causes surrounding tank water to be sucked in as well. Then it all shoots out together through the diffuser, increasing the amount of total flow within the tank.
ed2.jpg

eductor.jpg
 
Holy cavitation induced bubble screens BatMan!!!

Greg,

My monitor is about to swim the fishes and I can't see detail on this thing. How much larger is the Eductor compare to the Penductor?
 
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