Fluid Dynamics Expert Opinion Please?

[Aqualund]

Okay so I have a very large system driven by a 12,000gph pump and 3in. diameter pvc for the main distribution line.

In researching I have found that my reeflo hammerheads use insanely much less electricity per gph. So I am thinking instead of one pump I would run 3 of the hammerheads, and save nearly $200/mo in operational cost.

I am thinking that connecting them all inline to the main 3in pipe with directional wyes should be sufficient, but I would like some clarification on the best way to hook 3 4,500gph pumps onto one distribution pump and ensure they dont cancel each other out.

Any advice?

 

[SGT_York]

You have the idea use sanitary T's or other wier specific piping. Start with a single 1.5 or 2" and increase the diameter to 2.5" join with the second pump, then increase to 3" and join the third. So long as you increase before the join the friction loss will be kept low.

 

[Aqualund]

Thanks for your response Sgt. York. Before I make a decision on which way to go, Chris from Reeflo responded to my question and said to run the three pumps in parallel. Any comment on which way is better?

 

[jsilver]

One reason people run multiple pumps in parallel though separate lines is that if one fails, the others keep running. If you hook 3 pumps into one line and one fails, the water pumped by the other 2 may choose the path of least resistance and back flow through the non-operational pump. That is at least until you get a chance to close the output valve for that one pump.

 

[Aqualund]

I think what you are imagining as "into one line" is actually parallel. While running separate lines is not parallel...its just separate lines.

Like here...this is parallel:
http://kb.eng-software.com/questions/369/Running+Dissimilar+Pumps+in+Parallel

Sgt York was describing series...in which the output of one feeds the the input of another.

Running separate lines keeps the pumps from interacting at all. I am looking to run 3 pumps in parallel.

 

[wolfblue]

I believe SGT_York is thinking parallel, and you could do it that way... increasing the manifold size after each pump. Or you could just run all three into the 3", which is plenty big for 12k GPH btw. But if you do that you probably better think about check valves. I know, I hate them also. But if you turn off one pump you'll be pumping some percentage in a circle. It could be a large percentage and maybe even spin the off pump backwards.

So if its three 1.5" pumps into a 3" pipe you need three 1.5" check valves.

 

[Aqualund]

I believe SGT_York is thinking parallel, and you could do it that way...

You mean series

 

[wolfblue]

I "was" thinking parallel. If Sarge was thinking series it was because you said "hook 3 4,500gph pumps onto one distribution pump ". I thought you meant one distribution pipe. I know Sarge knows what he's doing in this area, and a series boost pump arrangement would be very unusual in a home aquarium. For series Sarge would have to run some calcs and have the pump curves. So I don't think he was onto series.

BTW, 12,000 GPH? A 3HP closed loop on a 400 gallon tank?

 

[Aqualund]

I "was" thinking parallel. If Sarge was thinking series it was because you said "hook 3 4,500gph pumps onto one distribution pump ".I thought you meant one distribution pipe. I know Sarge knows what he's doing in this area, and a series boost pump arrangement would be very unusual in a home aquarium. For series Sarge would have to run some calcs and have the pump curves. So I don't think he was onto series.

BTW, 12,000 GPH? A 3HP closed loop on a 400 gallon tank?

because you said "hook 3 4,500gph pumps onto one distribution pump ".

Yeah that was a typo. Meant to say into one distribution pipe.

BTW, 12,000 GPH? A 3HP closed loop on a 400 gallon tank?

Sorry? This isn't my system...is this in my profile or something? The system in question for this application is 3,000 gallons.

 

[wolfblue]

This isn't my system...is this in my profile or something?

No, just rambling before I had enough coffee to realize that 12Kgph was a bit much for 400 gallons. I thought I remembered you talking about a 400...

 

[SGT_York]

I was thinking parallel, using the pumps in series would be a pathetic waste of energy. Friction loss is exponential when increasing pressure of flow. So you really only use series pump to push water up a height or a long distance. Lower flow rates with larger diameter pipe is almost always better.

For best flow three 2" pipes will be the best. Depending if that will work for your tank needs, using the sanitary T's will help keep the flow going in case one pump goes out. You will have some loss but it will not be huge as flowing through a stopped impeller will halt most water flow.

The diagram is nice, I'd rather see one straight shot with the other pumps entering at a 45 angle. like a fishbone

picture fail

 

[Aqualund]

Okay perfect that's exactly what I intended to do. thanks for the time!