Help me figure my piping diameter

[Moe_K]

I have two systems to plumb on my 125g tank: a drain/return from the basement (about 6.5 feet of head) and an Ocean's Motion 4-way closed loop.

The drain/return will be powered by a Dolphin 2100; which should give me around 35 gallons/minute at around 80 inches of head. Which size pipes should I use for the drain/return lines?


The closed loop will be driven by a Pan World NH-50-PX-X pump: 1110 gph (at zero head). What diameter pipes should I use for the Ocean's Motion closed loop?

Thanks!

 

[Paula]

Hi Moe -
I just went through Matt's presentation so this is pretty fresh in my mind. My closed loops are running on 2 separate blueline pumps at 1200 gph. One splits off into two (going through an OM) the other is a straight shot.
I am running them on 1" right now and they emit an annoying humming vibration ... It makes me want to kill something - anything to make it stop.

Using the chart that Matt made I figured that I could use either 1.25" or 1.50" spaflex. I have decided to use the 1 1/2" spaflex to give me a little flexibility on pump size. I can now upgrade to a larger pump without having to re-plumb the system. I remember specifically that Matt said that even though the pump has 1" inlet/outlet that doesn't mean that that is the correct pipe diameter to use. You should use adaptors and/or reducers on the pump to bring them to the proper size. Also, there is a far better selection of fittings for 1.5" pipe than 1.25" pipe.

I am re-doing the loops to repair a leaky bulkhead (yes, at the bottom of the tank - UGH) so this is the time for me to take care of the piping as well. Pray for quiet plumbing . ... please.

Hope this helps. And Matt . . .correct me if I am wrong.
Paula

 

[Matt L.]

Weren't you there?!?

I have two systems to plumb on my 125g tank: a drain/return from the basement (about 6.5 feet of head) and an Ocean's Motion 4-way closed loop.

Moe, Paula pretty much told you the way it is.

Just to clarify, when we apply the sizing guidelines, we're only talking about pipes flowing full. Overflow/gravity returns from the tank cannot be practically sized using the guideles I set forth, and as such, are best sized simply as large as possible.

The drain/return will be powered by a Dolphin 2100; which should give me around 35 gallons/minute at around 80 inches of head. Which size pipes should I use for the drain/return lines?

This will give you 2100 gph. Going to my chart, you're definitely going to need a 2-in. dia pipe. It is unlikely you could squeeze by with a 1.5-in. dia. pipe. For the gravity return from the tank to the sump, I would use at least a 3-in. pipe, maybe even a 4-in.

The closed loop will be driven by a Pan World NH-50-PX-X pump: 1110 gph (at zero head). What diameter pipes should I use for the Ocean's Motion closed loop?

Well, if you can give me a link to where I can buy an Ocean's Motion (I can never find their page!), you would need a 1.25" dia. pipe for flow from the pump to the OCean's Motion and for flow from the tank to the pump. You could try a 1.5" dia. pipe, which, although larger, will give you less loss, if you're concerned about preserving as much of that 1100gph as possible. If it is an Ocean's Motion 4-way, 1100gph split four ways gives you 275gph. You could use a 3/4-in. line for each of the four splits.

Thanks!

No problem,

Matt

 

[Paula]

Hi Matt and Moe. . .
My Oceans Motion is plumbed to alternate from one line to another (like a SCWD) so each line would be handling the fulll 1200 gph . ...
Depending on how the 4 way is plumbed . .. 3/4 may not be sufficient. If each outlet is handling the full flow alternately, then you would need to look at at least 1.25" pipe ... But if 2 outlet are always on at the same time . ... then the flow would be cut in half.
Right?
BTW, the OM site is: http://www.oceansmotions.com/

 

[Liam]

Moe,i would use 3 overflows of 1.5 inches each,i think a 1.5 inch overflow will handle 1500gph.I recommend using multiple incase of blockage in one.Same way i use 2 return pumps from my sump,if one fails the system will still run perfectly.

 

[Moe_K]

Hi Matt and Moe. . .
My Oceans Motion is plumbed to alternate from one line to another (like a SCWD) so each line would be handling the fulll 1200 gph . ...
Depending on how the 4 way is plumbed . .. 3/4 may not be sufficient. If each outlet is handling the full flow alternately, then you would need to look at at least 1.25" pipe ... But if 2 outlet are always on at the same time . ... then the flow would be cut in half.
Right?
BTW, the OM site is: http://www.oceansmotions.com/

Yeah, here's another quandry.
What diameter pipes to use for each branch of the OM 4-way?
I have two drums to choose from: one has 1 and a half holes, and the other has 2 holes. So if I use the 2 holed drum, the active pipes will have to handle 600 gph each. If I use the 1.5 holes version, then one pipe would handle 900 gph and the other 300 gph.

 

[Matt L.]

Correction in Recommendation

Yeah, here's another quandry.
What diameter pipes to use for each branch of the OM 4-way?

Yes, I rescind my earlier recommendation. I wasn't thinking about how the Oceans Motions worked. So definitely scratch the 3/4".

I have two drums to choose from: one has 1 and a half holes, and the other has 2 holes. So if I use the 2 holed drum, the active pipes will have to handle 600 gph each. If I use the 1.5 holes version, then one pipe would handle 900 gph and the other 300 gph.

I don't have the pipe table with me, but here's what you do.

If you use the drum with 1.5 holes, assume one line gets 733gph and the other gets 367gph. I don't know where you got 900gph. The 733gph, being the larger, is limitting, so use that as your design value. Now go to the piping table and find the diameter of pipe that leads to a flow of 733gph yielding a line velocity somewhere between 3ft/sec and 5ft/sec, trying to stay as close to 3ft/sec without going too far under. You should come up with a diameter of 1.25-in. A 1-in. diameter will give you a velocity too high.

If you use the drum with 2 holes, each line gets 550gph, thus each line need only be 1-in. by my estimation, but why design around the 2-hole drum? If you design for 550gph, it may be tough to switch it out for the 1.5-hole drum? I would therefore design around the 1.5 hole drum. Too low of a velocity is sort of a problem, but nowhere near as much of a problem as too high.

So without the table in front of me, I say make each line from the OCeans Motion to the tank be 1.25-in.

Matt

 

[Matt L.]

Hi Matt and Moe. . .
My Oceans Motion is plumbed to alternate from one line to another (like a SCWD) so each line would be handling the fulll 1200 gph . ...
Depending on how the 4 way is plumbed . .. 3/4 may not be sufficient. If each outlet is handling the full flow alternately, then you would need to look at at least 1.25" pipe ... But if 2 outlet are always on at the same time . ... then the flow would be cut in half.
Right?
BTW, the OM site is: http://www.oceansmotions.com/

Paula,

Thanks for the correction. About your earlier concern over vibration in the line, that may be caused by pump vibration as well as too high a flow. In the event that increasing your pipe doesn't eliminate the noise (you should still increase the line size to get the best performance out of your pump), try adding a flexible connector between the pump and the line. What I do is take two threaded barbs of the same line size and face them towards each other along a straight section, perhaps 9-in. apart. I cover the barbs with silicone, and add a section of flexible, vinyl tubing. Then, before the silicone dries but after I have well secured the tubing (I boil the ends of my tubing for a few seconds to make it nice and soft so it goes all the way on), I add a metal hose clamp and secure it tightly. This seems to help diminish vibrations sent from the pump to a rigid line,

Matt

 

[Moe_K]

This will give you 2100 gph. Going to my chart, you're definitely going to need a 2-in. dia pipe. It is unlikely you could squeeze by with a 1.5-in. dia. pipe. For the gravity return from the tank to the sump, I would use at least a 3-in. pipe, maybe even a 4-in.

Matt, just a follow up question: there are 2 drains on the 125 gal tank. What diameter pipe should I use on each return: maybe a 1.5" pipe that meets the other side in a Y, then becomes a 3" pipe?

Thanks again!

 

[Matt L.]

Art over Science

Matt, just a follow up question: there are 2 drains on the 125 gal tank. What diameter pipe should I use on each return: maybe a 1.5" pipe that meets the other side in a Y, then becomes a 3" pipe?

Moe,

Because drain lines are open channel flow, computation of the appropriate diameter is far, far more complicated.

Yet similar to sizing closed conduit flow lines, the biggest error would be to make these lines too small. With open channel flow, the bigger the line, the quieter it will be.

That said, I am going to suggest, through a series of commin sens assumptions, analogies, and voodoo, that you use two 1.5-in. or 2-in. lines that meet to form a 3-in. line (there's no 2.5-in. pipe, right?)

Matt