my diy needle wheel dart pump

[spazz]

well im sure there are alot here that have been keeping track of the thread about the needle wheels that sequence is having designed. the engineers are working with one of the 1000 series pumps to creat a masive needle wheel pump. the big flaw there is that the pump draws 398 watts! i think they need to use the dart pump for a needle wheel. so i created my own version of it.
the first test was a disaster! i couldnt get it to draw enough air at that head presure. the testing tank is a 14.5"wide 6 foot tall octgon aquarium. i think its 75 gallons. not for sure though. with the test tank half full i could draw almost 60 scfh through the pump. it makes super fine bubbles. but the minute i put any more water in the tank it wouldnt draw much air.
at that point i almost scrapped the whole idea. but then i got out my sweetwater air pump and air stones. that pump is awesome. huge volume of air and almost silent. so in went the stones. it was even worse than the first test. the bubbles were huge!
so i sat there and though about it for a while. then took the air pump and hooked it stright to the sequence dart. holy bucketts! i though the tank blew up! water was flying! foam was flying! so i shut it down. hummmmmmmmmm what now???? duhhhhhhhhh stick an air regulator in the air line dummy! so in went the air meter in line. cranked it back up again. we have lift off! that pump can be force injected! i cranked it up to 80scfh and it was still running. but the bubble size was a little too big. so i backed it down to 70 scfh the bubble size is as good as an ocean runner 3700 and runs at a total wattage of 161 watts. thats both the sequence dart and the sweetwater air pump combined. i think with some tweaking the pump could handle 80 schf. because i put the fittings so high up and the body(had the reach in there to get the 90 fitting on there) it causes the pump to cavitate due to restriction. when the fitting is off the pump outlet the pump can handle alot more air. but the bubbles dont go all the way to the bottom of the test tank. well enough blah blah out of my mouth. here is the pics from the test.

 

[Sonia Taro]

gotta tag along on this one. Are there any pictures of the needle wheel??

 

[spazz]

if i ever get it prefected i might post pics. right now its not perfect so i dont want to post pics of something that could blow up in someones house and make a huge mess. the one good thing about the dart pumps is they are low speed pumps. its easer to get them to run smooth with out ballancing the impellors. mine runs smooth and quiet until you inject the air in it. then it gets a little louder. the chopping up of the air bubbles makes any pump have a little noise. but its not much. time will tell if this will become the next hot skimmer pump or not. it will be interesting to see how the sequence design works and how much air it will draw.

 

[dgasmd]

Very cool. I do have a few questions:

1. Why did you put the pump's oulet so high on the chamber? I realize this is for testing purposes, but I figured you would put it much lower like the other needdle wheels.

2. How big or small are the bubbles compared to the sedra or ocean runners you use in other skimmers?

3. What diameter is that chamber? It looks pretty full with the single pump.

4. How much air is it drawing?

5. Seems like you used 1/4 ID RO tubing for the air intake. Why not go bigger and allow more air to come in with something like 3/8" or even 1/2"?

Thanks and looking forward to seeing more of it. This is pretty exciting stuff!!!!!!

 

[ErikS]

Spazz you are insane! (& to me that's the highest form of compliment )

Can't wait to see this with all the bugs worked out. I'm subscribing to this thread.

 

[dgasmd]

<a href=showthread.php?s=&postid=6322747#post6322747 target=_blank>Originally posted</a> by dgasmd
Very cool. I do have a few questions:

1. Why did you put the pump's oulet so high on the chamber? I realize this is for testing purposes, but I figured you would put it much lower like the other needdle wheels.

2. How big or small are the bubbles compared to the sedra or ocean runners you use in other skimmers?

3. What diameter is that chamber? It looks pretty full with the single pump.

4. How much air is it drawing?

5. Seems like you used 1/4 ID RO tubing for the air intake. Why not go bigger and allow more air to come in with something like 3/8" or even 1/2"?

Thanks and looking forward to seeing more of it. This is pretty exciting stuff!!!!!!

I must apologize. I did not read the first post as it was a link from the other thread and after looking at the pictures I did not realize there was writting at the top. I just read it again and answered all my questions pretty much. This gets better by the minute.

 

[slug]

Nice, but think it will need 1 or 2 more pumps.

 

[Sanjay]

Forcing air into the needle wheel is one way to address the height limitations of some of the tall needle wheel skimmer designs. I was fooling around with my beckett one time pumping air into it.

sanjay.

 

[spuzio]

SPazz, i am interested in seeing the pump in operation. Do you have any video of it in operation?

 

[Herbert T. Kornfeld]

I see some issues that if corrected could improve the air intake greatly. First, you need to get a larger air inlet...1/2" PVC or something. The second thing is the inlet venturi is designed wrong....well, not wrong, but not as good as it could be. The diameter of the pipe where the air comes in is the same as the rest, so the air intake is depending only on the suction of the pump alone. This is not a true venturi. If you were to reduce the diameter of the intake pipe where the air enters, the conservation of energy laws would mean that the pressure of the water would drop even more, sucking in that much more air due to the increased velocity of the water going through this pipe.

In the design I made (just waiting on a NW dart), the pump is positioned higher on the body (but its nice to know it works well that much farther down...thanks spazz), and has its outlet extended 4' down into the skimmer...like a downdraft tube after the pump. This way, the back-pressure on the air-inlet is mimimal, and the pump just has to deal with the pressure of moving that water&air mix downward...which is much easier for a NW to do.

Ill post a pic...er, maybe a diagram later (a pic would make no sense without the pump in place)...but if you are familiar with how industrial flow eductors/venturis are made...with the valve on a bypass, you will see what I am getting at.

 

[Donw]

Looks like just a small disc / donut glued inside the tube just before the air inlet would give you plenty of suck without the air pump.
May be worth a shot, works fine with the little pumps.

Don

 

[Herbert T. Kornfeld]

During the air inlet would be best...so maybe a section of hose sliced the long way (so it looks like a "C"), and inserted in the pipe so the opening of the "C" is where the air is let in. The disk or donut would be a minimal improvement at best, as you really want to restrict the water and add the air IN this restriction, not after it, for the best results. If possible, the air inlet might be able to be drilled into the side of the valve, but the results of that might be marred by the turbulence that the ball-valve creates.

The easiest, and most adjustable isnt that hard to do...I'll make the diagram later...is just needs a couple elbows, 'T's, and some smaller diameter pipe...what diameter is best...who knows...maybe 1", maybe 3/4", but then this would be a functioning venturi more than just relying on the pump to suck in air by its own suction like it is now....this would also allow for t to be mounted lower on the skimmer.

 

[spazz]

the big problem with putting a venturie on a pump that size it the restriction on the pump itself. the more water flowing through the pump causes the bubbles to be chopped smaller. if i closed the valve a little on the intake pipe to creat a stronger suction for the air inlet, the pump didnt perform as well. now you have to consider the fact that this is a pump test stand not a venturie test stand. i want to see how much air can be run through this pump and how small i can make the bubbles. the more air you push through the pump the more water you have to have with it.
i think i have to redesign the impellor a little different so it will suck air better. even with the water low in the test tank it wouldnt suck more than 60 scfh. when i hooked up the air pump to the pump i could inject 80cfh to the pump and it dont cavitate.
i want to order the impellor for the 4300 and modify it to see how it works. i think the increased water flow will allow me to inject about 13% more air to the pump. im hoping to get it to run the same small bubbles its making and still push 75 scfh into the pump. we will see.
here is the numbers im looking at. total air intake to the pump. along with bubble size. and wattage draw with both pumps running. i want to make a pump that is more effecient than having a bunch of sedras or eheims on a skimmer. rught now this pump is equil to 3 oceanrunner 3700 in air intake and 2 1/2 3700's in wattage draw.
if i can get the pump to suck more air instead of pushing air to the pump the wattage will drop down to around 120 watts. at 60schf. those would be some effecient numbers.

 

[Donw]

<a href=showthread.php?s=&postid=6325807#post6325807 target=_blank>Originally posted</a> by Herbert T. Kornfeld
The disk or donut would be a minimal improvement at best, as you really want to restrict the water and add the air IN this restriction, not after it, for the best results.

It goes in the IN side just before the air inlet and it will slightly restrict the flow. "Minimal improvement at best" is not really correct. If you play with the hole size alittle you should be able to cavitate the pump with no problem what so ever.

Don

 

[Herbert T. Kornfeld]

The usual power curve for this pump gets thrown out the window though because its no longer just pumping water...something tells me that it wont go much below 160watts.

No doubt on the air intake however...a pump like that should be able to take in alot more air and not cavitate due to its lower speed (it would prolly choke on air before cavitating). Its water throughput might go down however...but that is where the delicate mix between depth, plumbed restriction, etc comes in. Simply using a larger diameter for the air intake should ease things up as well. What diameter pipe are you using right now on the intake and output...all 1.5"?

 

[Herbert T. Kornfeld]

"It goes in the IN side just before the air inlet and it will slightly restrict the flow. "Minimal improvement at best" is not really correct. If you play with the hole size alittle you should be able to cavitate the pump with no problem what so ever."

-Donw

It might help if the turbulence is just right...depending on the velocity of the water...but to introduce air WHILE maintaining a higher velocity is the whole point of a venturi...if its used as an inlet or outlet. That disk can help, but its just relying on the restriction of the disk to make the pump suck in more air...

As far as the pump cavitating...Ive seen darts run with the valves shut and no cavitation happens...and Im not really sure what you are getting at with that part...we arent trying to get it to cavitate after all...that would be a bad thing.

 

[spazz]

<a href=showthread.php?s=&postid=6325938#post6325938 target=_blank>Originally posted</a> by Herbert T. Kornfeld
The usual power curve for this pump gets thrown out the window though because its no longer just pumping water...something tells me that it wont go much below 160watts.

when the tank is half full and the pump was sucking air on its own not being force into it. the wattage was down to 110w thats because it takes less power to move air than it does to move water. so the more air injected into the pump the lower the wattage went on the meter. but at a certan point the bubbles were too big. if i really created a large restriction on the pump almost to the point of cavitating it, the pump only drew 95 watts. but it wasent pulling much air either. there is a giant curve there. the more air, the less watage. the less water the less air, the lower the wattage. so im trying to find the best of all 3 lowest wattage, highest air, and highest water.

 

[Donw]

<a href=showthread.php?s=&postid=6326003#post6326003 target=_blank>Originally posted</a> by Herbert T. Kornfeld
"It goes in the IN side just before the air inlet and it will slightly restrict the flow. "Minimal improvement at best" is not really correct. If you play with the hole size alittle you should be able to cavitate the pump with no problem what so ever."

-Donw

It might help if the turbulence is just right...depending on the velocity of the water...but to introduce air WHILE maintaining a higher velocity is the whole point of a venturi...if its used as an inlet or outlet. That disk can help, but its just relying on the restriction of the disk to make the pump suck in more air...

As far as the pump cavitating...Ive seen darts run with the valves shut and no cavitation happens...and Im not really sure what you are getting at with that part...we arent trying to get it to cavitate after all...that would be a bad thing.

Not that you would want to cavitate but you would have the ability to suck as much air as possible. Installing the disc is not a true venturi. It just creates a low pressure area. Since really its pressure difference that makes it all work any how. I'm sure we could come up with a nice well designed venturi but for this application it really doesnt need to be over done.

Don

 

[spazz]

<a href=showthread.php?s=&postid=6326052#post6326052 target=_blank>Originally posted</a> by Donw
Not that you would want to cavitate but you would have the ability to suck as much air as possible. Installing the disc is not a true venturi. It just creates a low pressure area. Since really its pressure difference that makes it all work any how. I'm sure we could come up with a nice well designed venturi but for this application it really doesnt need to be over done.

Don

thats why the valve is installed in the intake pipe. an ajustable restriction to get maximum air to water ratio. its a cheap easy way to do it. i dont have a lathe (yet) to make venturies on. so i have to make due with what i have. just remember herbert this is diy. i dont have a university lab to work in. its just my garage. i would love to have a design lab. but i dont. :rollface:

 

[Donw]

<a href=showthread.php?s=&postid=6326175#post6326175 target=_blank>Originally posted</a> by spazz
thats why the valve is installed in the intake pipe. an ajustable restriction to get maximum air to water ratio. its a cheap easy way to do it. i dont have a lathe (yet) to make venturies on. so i have to make due with what i have. just remember herbert this is diy. i dont have a university lab to work in. its just my garage. i would love to have a design lab. but i dont. :rollface:

The valve will just adjust the water inflow. Its not going to create a low pressure area. The dead spot barely just behind the disc I was explaining is the low pressure area the ambient room is the high pressure so between the two you get vacuum.

Don