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  #1  
Old 01/08/2008, 03:53 PM
RonD RonD is offline
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90 degree fittings

are there better styles of 90 degree elbows than others in say 1.5 and 2" plastic fittings ? in regards to less flow loss.
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  #2  
Old 01/08/2008, 04:01 PM
RonD RonD is offline
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IE if I could find something like this for better flow
http://www.vacdepot.com/product-info...cvsi/17409.jpg

versus something like a typical 90 like this

http://outdoorelementspa.com/tn_90-Degree-Elbow-S40.jpg

how much gain would I get from the top one over the typical 90
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  #3  
Old 01/08/2008, 04:12 PM
scbadiver scbadiver is offline
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If you have the space to work with, the drain/waste fittings work well. they are all wider, sweeping turns. Available at Lowes, HD etc.
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  #4  
Old 01/09/2008, 02:52 PM
kgross kgross is offline
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The difference will be related to the velocity of the water flowing in the pipe. If the keep the velocity low, but using larger pipe, the better sweeping L, will not make a noticeable difference in flow. Now if for some reason you can't use larger piping and have a very high pressure pump, the quality of the fittings will make a very noticable difference in flow.

But for our normal pumps, just up size your plumbing one or 2 sizes and you can put the whole pipe together out of street ells and use no straight pipe and get more flow than undersized piping with great sweeping curves and a limited number of fittings total.

Kim
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  #5  
Old 01/09/2008, 03:16 PM
NanoReefWanabe NanoReefWanabe is offline
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i cant see the pics on the first link...

but sweeping will be much better in the long run...i was told not to use Grey electrical conduit though...not sure if that is what yo posted or not...also if you cant find sweeping 90* then two 45* will flow considerably better then a standard 90*
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  #6  
Old 01/09/2008, 04:25 PM
not_sponsored not_sponsored is offline
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Try flex PVC, much less added head.
  #7  
Old 01/09/2008, 04:33 PM
kgross kgross is offline
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Just don't worry about the elbows and go one size larger in pipe. Easier to work with less expensive than flexable PVC and you still have a lot less head pressure.

Kim
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  #8  
Old 01/09/2008, 08:05 PM
not_sponsored not_sponsored is offline
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Quote:
Originally posted by kgross
Just don't worry about the elbows and go one size larger in pipe. Easier to work with less expensive than flexable PVC and you still have a lot less head pressure.

Kim
You wouldn't think so but larger pipes will actually add more head. Trust me, I'm an engineer.

http://www.engineeringtoolbox.com/re...gth-d_192.html
  #9  
Old 01/09/2008, 09:34 PM
kgross kgross is offline
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I don't need to trust you. A larger pipe will has less frictional flow losses than a smaller pipe providing the friction coefficient is close to the same.. IE smooth pvc pipe for both pipes.. The Velocity of the water is less in a larger pipe at the same flow rate, so you have less friction in the pipe. Your table that you should is to help calculation friction using just length of pipe rather than adding in the actual fittings that you are using. The velocity is what makes the larges effect in friction.

http://www.efunda.com/formulae/fluid...e_friction.cfm

Here is how you calculate the friction of a fluid in a pipe.

Trust you your an engineer, so why do you say you are an engineer and a student at the same time? Me I already have an engineering degree.

kim
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  #10  
Old 01/09/2008, 11:25 PM
not_sponsored not_sponsored is offline
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You're talking about the major head loss, which really has nothing to do with the fittings, I'm talking about minor head loss. Of course there will be less major head loss in a system if the velocity is lower, but what I was saying is that the fittings, if larger, will increase the minor head loss in the system. The thread IS titled "90 degree fittings" not "what size pipe produces the least amount of friction"

You should go back to school, maybe you will actually learn something next time.
  #11  
Old 01/09/2008, 11:30 PM
kgross kgross is offline
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I keep saying that going to a larger pipe will decrease the friction. You say it will increase the friction. Now you say a larger pipe will decrease the Major head loss, but it will increase the minor head loss. Now I'm not sure but to most people major is bigger and more important than minor. So if the OP increases the size of his pipe by one or even two sizes, trying to find the best 90 degree turn will not make any difference since the major friction losses have been decreased.

I'm not the one that stated "You wouldn't think so but larger pipes will actually add more head. Trust me, I'm an engineer." in reference to a large pipe decreasing head.

Maybe you should start paying a little more attention in your fluid dynamics classes.
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  #12  
Old 01/09/2008, 11:49 PM
not_sponsored not_sponsored is offline
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Lol

If you have 5-8 fittings in 6-8 feet of pipe, what's going to cause more head loss, the pipe friction or the fittings. Think about it.
  #13  
Old 01/09/2008, 11:58 PM
not_sponsored not_sponsored is offline
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If you're pumping 1200 gph in the pipe, the difference between a 1.5" pipe and a 3" pipe is 2.5 feet of head per 100 feet of pipe. In this case you'll be working with less than 10 feet of pipe or .25 feet less head by switching from a 1.5" pipe to a 3" pipe, TWICE THE DIAMETER.

http://www.engineeringtoolbox.com/pr...pes-d_404.html

On the other hand, lets say we have 5 90 degree fittings, for 1.5" pipe that would add 4 feet of head for every 90, or 20 feet of head.

Using 3" pipe we would add 7.9 feet of head for every 90 or 39.5 feet of head.
http://www.engineeringtoolbox.com/pv...ngs-d_801.html

This is a difference of 19.5 feet for the different sized pipes, for MINOR head loss. Compare this with the .25 feet of head loss caused by decreasing the pipe size in MAJOR head loss.
  #14  
Old 01/09/2008, 11:59 PM
kgross kgross is offline
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Use the science... Here are numbers that you can duplicate using the RC head loss calculator.

We will use a mag 12.5 pump, with 4 feet vertical head, 3 feet horizontal, and 5 elbows.

One with 3/4 inch pipe
One with 1 inch Pipe
one with 1 1/4 pipe

Then we will run the same numbers but we will use your 3/4 inch spa flex and say that there are no elbows at all and the same with 1 inch.

3/4 pipe with elbows
Total losses are 9.11 feet of head pressure, or 3.94 PSI. with a flow rate of 681 GPH. Process took 43 iterations.

1 inch pipe with elbows
Total losses are 6.82 feet of head pressure, or 2.95 PSI. with a flow rate of 891 GPH. Process took 103 iterations.

1 1/4 pipe with elbows
Total losses are 5.15 feet of head pressure, or 2.23 PSI. with a flow rate of 1017 GPH. Process took 142 iterations.

Now your version with no elbows, should have more flow than larger pipe correct?

3/4 no elbows or other fittings just 7 feet of pipe
Total losses are 7.68 feet of head pressure, or 3.32 PSI. with a flow rate of 816 GPH. Process took 79 iterations. hmm, less than 1 inch with 5 elbows

1 inch with no elbows
Total losses are 5.76 feet of head pressure, or 2.49 PSI. with a flow rate of 974 GPH. Process took 125 iterations. Hmm less than 1 1/4 with 5 elbows

Total losses are 4.61 feet of head pressure, or 1.99 PSI. with a flow rate of 1052 GPH. Process took 155 iterations.

So yes better turns will increase flow, but if you put in larger pipe it makes more of a difference than any type of elbow that you use.

Kim
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  #15  
Old 01/10/2008, 12:10 AM
kgross kgross is offline
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Quote:
Originally posted by not_sponsored
If you're pumping 1200 gph in the pipe, the difference between a 1.5" pipe and a 3" pipe is 2.5 feet of head per 100 feet of pipe. In this case you'll be working with less than 10 feet of pipe or .25 feet less head by switching from a 1.5" pipe to a 3" pipe, TWICE THE DIAMETER.


This is correct.
Quote:

http://www.engineeringtoolbox.com/pr...pes-d_404.html

On the other hand, lets say we have 5 90 degree fittings, for 1.5" pipe that would add 4 feet of head for every 90, or 20 feet of head.

This is not correct. Your table is not in feet of head loss, it is in equivalent feet of pipe, so for the 1.5 inch pipe you would at 4 feet of pipe lenght, so with 5 90s you would now be working with 30 feet of pipe not 10, so the head would be apox .8 30/100 *2.5 feet /100 feet
Quote:


Using 3" pipe we would add 7.9 feet of head for every 90 or 39.5 feet of head.
http://www.engineeringtoolbox.com/pv...ngs-d_801.html

For the 3 inch pipe a 90 adds 7.9 feet so 5 times 8 is 40, so we are working with 50 feet of pipe

So 50/100 * .1 equals .05 feet of head pressure.

Quote:

This is a difference of 19.5 feet for the different sized pipes, for MINOR head loss. Compare this with the .25 feet of head loss caused by decreasing the pipe size in MAJOR head loss.
So once you use the tables correctly you change from .8 feet to .05 feet A difference of .75 feet or apox 1600 percent decrease in friction by going from 1.5 inch to 3 inch pipe at 12000 gph

Please learn how to use your tools.
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  #16  
Old 01/10/2008, 12:15 AM
kgross kgross is offline
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If you read the top of the table this is what it says.

PVC - Equivalent Length Friction Loss in Fittings
Minor loss for PVC and CPVC fittings in equivalent length of straight pipe

Sponsored Links

Approximate friction loss for PVC and CPVC fittings in Equivalent Length in feet of Straight Pipe for water can be found in the table below:

Notice the Equivalent Length in feet of straight pipe. Not equivalant feet of head pressure!
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  #17  
Old 01/10/2008, 12:20 AM
kgross kgross is offline
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Friction loss in pipe is not hard to think about. The velocity of the water against the side of the pipe is what causes the friction. If you slow the velocity down, the friction goes down. Now increasing the size of the wall, does increase the amount of friction since there is more area, but the decrease in velocity makes up for the increase in area. When it comes to turns, think about your car, a hard turn at high speed throws you against the door, (more flow loss), take that same hard turn at a very slow speed, and you don't get pushed against the door (less flow loss)
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  #18  
Old 01/10/2008, 03:04 PM
RonD RonD is offline
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I hope there has been no black eyes on this one hehe.. thank you both for your input.. I think, I get it.

The run I am doing is from a hammerhead pump 5600GPH. will be using 2" input and 1.5" output. The rise from the output side of the pump will be 8' - into a 90 - over 4' on the horizontal - into a 90 - then up another 6' before it enters my display distribution manifold. The 90's will be either the 2 45's or the longer sweeping 90.
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  #19  
Old 01/10/2008, 03:26 PM
kgross kgross is offline
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With that length of run I would suggest that you change as much of your intake as you can over to 3 inch pipe and run our output as 3 inch or at least 2 inch until it gets to your distribution manifold..

If you can't just to give you some numbers in 1.5 inch pipe with 40 feet total pipe (I calculate 18 feet on your numbers and then double that for the pump intake) going from 6 to 7 elbows only decreased the flow by 30 gph.

If you use 2 inch pipe up to your manifold, a normal 90 will have less resctriction than your 1.5 inch pipe with no direction changes at all. So I would still suggest go one size larger in pipe and don't worry about finding great fittings, you can use what ever is easy to find locally.

Kim
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  #20  
Old 01/10/2008, 04:26 PM
xtm xtm is offline
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Quote:
Originally posted by RonD
IE if I could find something like this for better flow
http://www.vacdepot.com/product-info...cvsi/17409.jpg

versus something like a typical 90 like this

http://outdoorelementspa.com/tn_90-Degree-Elbow-S40.jpg

how much gain would I get from the top one over the typical 90
The difference is negligible. Trust me, I'm a PVC salesman
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  #21  
Old 01/10/2008, 06:20 PM
nodbugger nodbugger is offline
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High speed, low drag. Low speed, high drag.

A sudden expansion in pipe sizes will decrease the flow and it will suffer from head loss because the water has to slow down, which also increases the pressure.



http://www.efm.leeds.ac.uk/CIVE/CIVE...pe%20flow2.pdf
  #22  
Old 01/10/2008, 08:10 PM
RonD RonD is offline
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this is what sequence/reeflo had to say about pipe size. the only thing that has changed since I talked to them is adding in two 90's. as for the intake side, it will be a straight shot to the intake.

Hi there,

I am the proud owner of one of your Dart pumps. Had it for a few years now and still going strong. Currently it is powering my 300 gallon reef set up. The head on the pump is about 5 feet before it enters my display tank.

I am looking at lowing a portion of my system (sump etc) into the basement directly below where it is now to cut down on pump noise.. this drop would add about 9-10 feet of head to what I already have. I am looking at the Hammerhead and the 5800SEQ23. Which one will work better for me? I presently run a 2 inch pipe on the intake and 1.5 on the out. I see both the pumps I have chosen to replace my Dart are 1.5 on each end. should I stay with that or will it help me to continue with the 2" on the intake with which ever pump I choose. The run up to the tank is a straight shot with no bends until it gets up to the tank. I am hoping to get similar pressure to what I have now. ideas, tips ???

Thanks Ron D
Victoria BC Canada
--------------------------------------------------------
Hi Ron,
Glad to hear that you are enjoying your Dart.
First of all, if you already have the 2" piping setup to go into a pump, I would encourage you to stay with it. All you need is an adaptor to increase the pump intake hole to 2". Running the 2" will give you slightly more flow and slightly less head pressure, so using the 2" on the intake will benefit you.
Second, the Hammerhead and the 5800SEQ23 are actually the same pump. The 5800SEQ was originally part of the watergarden line so it comes standard with freshwater seals. The Hammerhead was mirrored off of the 5800 for the ReeFlo series and comes standard with saltwater seals. As i am sure you have noticed, you can order the 5800SEQ23 with saltwater seals, but that is why you are seeing a difference in price between the 5800 and the Hammerhead. There is an extra labor charge with the 5800 cause the seals need to be switch to saltwater. So the best pump to go with is the Hammerhead because they cost less cause they are made for saltwater use.
From what you said in your email, it sounds like you will be at about 15-16ft of head pressure. You will not be adding much additional friction loss as long as you stick with the 1.5" piping on as much of the discharge as possible. The Hammerhead will give you about 3300gph at that head pressure, which will work very well for a 300gallon tank. If you find that you are getting a little too much flow, it is safe to valve our pumps down on the discharge side and that is not harmful to the pump. A quarter valve down can actually save up to 10% on watt draw.
Please let me know if you have an further questions or concerns. Thanks,
Beth Franklin
ReeFlo Inc.
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  #23  
Old 01/10/2008, 08:42 PM
kgross kgross is offline
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Is this pump going to be your return pump or a closed loop pump? If it is return why are you trying to do 3000 + gph through your sump?
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  #24  
Old 01/10/2008, 08:49 PM
NanoReefWanabe NanoReefWanabe is offline
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Quote:
Originally posted by nodbugger
High speed, low drag. Low speed, high drag.

A sudden expansion in pipe sizes will decrease the flow and it will suffer from head loss because the water has to slow down, which also increases the pressure.



http://www.efm.leeds.ac.uk/CIVE/CIVE...pe%20flow2.pdf
i would tend to agree with this too..larger pipes are going to have more water in them....more water is going to weigh more...and move slower...both are going to increase head pressure...i dont need to be an engineer to know that i can blow water up a straw a good 5 feet or so...but you can bet your butt i cant blow any amount of water up a garden hose 5 feet...and my lung capacity is going to be the same in either setup...LOL
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  #25  
Old 01/10/2008, 08:53 PM
NanoReefWanabe NanoReefWanabe is offline
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Quote:
Originally posted by kgross
Is this pump going to be your return pump or a closed loop pump? If it is return why are you trying to do 3000 + gph through your sump?
3000GPH would be about 10X turnover for his setup...not including skimmer volume sump volume refuge volume...i dont think that is too far out of the question...most i think aim for about 5 times turn over through their sumps...i bet he would be pretty close to that after everything is added up...
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