90 degree fittings

[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/CIVE2400/pipe flow2.pdf

 

[RonD]

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.

 

[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?

 

[NanoReefWanabe]

<a href=showthread.php?s=&postid=11569244#post11569244 target=_blank>Originally posted</a> 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/CIVE2400/pipe flow2.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

 

[NanoReefWanabe]

<a href=showthread.php?s=&postid=11570448#post11570448 target=_blank>Originally posted</a> 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...

 

[NanoReefWanabe]

i am curious why they say that valving the pump will save on hydro though...i thought increasing head pressure would increase power consumption which in this case would be wasted as heat...i could see if you actually changed the power to the pump to slow it down then i could see how that would reduce flow and save power...

 

[kgross]

The weight of the water does not effect head pressure at all. The pipes and pump hold up the actual wight of the water. The only thing about the weight that effects the pump flow is the PSI at the pump output or vertical head.

The sudden increase in size or decrease in size does effect flow (normally not a very noticeable amount. The reason it does effect the flow is that the water has inertia and any change in the pipe causes the water to change direction or velocity, so it has to overcome the inertia. Just coupling 2 pipes together effects the flow rate via the same means that going to a larger pipe effects the flow.

Nano reef wanabe, before you say don't need to know any engineering you need to try the experiment out. You can blow the water up the same height, no matter what diameter the pipe is (unless you consider capillary movement ). Get a few feet of clear hose so you can see what you are doing. Put the hose in a U with the U down and see how far you can raise the water level in one side of the U. Try this with lots of different sizes of tube. You will find that the size of the tube does not make any difference.

Kim

 

[kgross]

Nano, this is why you need to understand how stuff works before you post about how it works. The pump "does work" when it moves water. The more water it moves the work is done. The more work that is done, the more power is needed. The pump is actually creating the same " pressure" no matter how much water moves, the amount of pressure that the pump creates determines how much water is moved. If there is lots of static head pressure, the pump has less pressure to overcome the dynamic head pressure (friction loss) to move water. So when you reduce the friction, there is more pressue left to allow a higher velocity of water to use up the pressure that is left.

Kim

 

[RonD]

<a href=showthread.php?s=&postid=11570562#post11570562 target=_blank>Originally posted</a> by NanoReefWanabe
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...

I run a manifold around the top of my tank with 9 outlets on it.. so you divy up 3000 x 9 outlets gets me about 300 gph out of each . see pic in the link below.
http://smg.photobucket.com/albums/v672/RonDronD/EQUIPMENT/?action=view&current=oldmanifold1inch.jpg

the picture is of an old manifold I made up first .. but you get the idea. bumped the diameter of it up to 1.5" piping

 

[jdieck]

<a href=showthread.php?s=&postid=11563896#post11563896 target=_blank>Originally posted</a> 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.

http://www.engineeringtoolbox.com/pressure-loss-plastic-pipes-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/pvc-pipes-equivalent-length-fittings-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.

Sorry to say but you are rading the equivalent lenght of fittings table wrong.
The table of equivalents will give you the equivalent in lenght of stright pipe not of feet of head loss.

A 3" 90* elbow is equivalent to 7.9 feet of stright 3"pipe and a 2" 90* elbow is equivalent to 5.7 feet of stright 2" pipe, a 11/2" 90* elbow is equivalent to 4 feet of stright 11/2" and so on.

Eventhough the equivalent straight pipe is higher the pressure loss is lower.
At a flow of 1200 gph .
7.9 feet of 3" pipe will have 0.0079 ft of head pressure drp
5.7 feet of 2" pipe will have 0.0456 ft of head pressure drop
4 feet of 11/2" pipe will have 0.104 ft of head pressure drop.

So in other words a 90* 11/2" elbow will have a head pressure loss that is 2.3 times larger than a 2" elbow.

If you drop the diameter to 1" that difference comes to that a 1" 90* elbow (2.5 ft equivalent) will have a pressure drop of 0.53 ft of head which is 11.6 times higher than the pressure drop across a 2" elbow eventhough its equivalent lenght is only 2.5 ft compared to the 5.7 feet of 2" elbow.

 

[RonD]

<a href=showthread.php?s=&postid=11570448#post11570448 target=_blank>Originally posted</a> 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?

its the Return.. and its a busy sump.. supplys my frag tank, algae tank and skimmer. it works lol

 

[kgross]

That is going to be a busy sump. Personally I would suggest slowing down your overflow and using that big pump as a closed loop. System will be a lot quiter and you will get much better surface skimming going into the skimmer.

Kim

 

[jdieck]

<a href=showthread.php?s=&postid=11570598#post11570598 target=_blank>Originally posted</a> by NanoReefWanabe
i am curious why they say that valving the pump will save on hydro though...i thought increasing head pressure would increase power consumption which in this case would be wasted as heat...i could see if you actually changed the power to the pump to slow it down then i could see how that would reduce flow and save power...

The change in power consumption on a centrifugal pump is proportional to the change in flow and also to the change in head.

The actual formula is:
BHP = (Q x H x SG)/(3960 x % EF)
where
BHP = Break Horse Power
Q = Flow in gal per minute
H = Pressure head in feet
SG = Specific Gravity (1.0264 for salt water at 35 PPT salinity)
3960 is conversion factor foot-pounds for horsepower and weight of 1 gal of water (33,000 / 8.33)
% Eff is the efficiency of the pump

So as you can see for a given required flow increasing the head will require an increase in power and for a given head increasing the flow will require an increase in power.
When you install a valve to restrict the output of a pump you do so by increasing the head so to keep the same flow more power will be required but because you do not change the motor size the flow will drop and the drop in flow makes the power drop. It just happens that the drop in flow reduces the power more than the increase of head increases it so the net effect is an overall drop in power.

Take a look at this chart.
In indicates a typical performance curve for a centrifugal pump and charts the head vs flow (which is the one we usually get from manufacturers); the BHP vs flow (That we should get from manufacturers but our aquarium pump manufacturers do not usually provide it, I think they are afraid we find out about power consumption claims being manipulated) and finally efficiency vs flow.

Note that all centrifugal pumps are usually designed to operate optimally at certain point where a combination of flow and head will intercept with the maximum efficiency; either before or beyond that point the efficiency will drop but power will drop for before the point and will increase beyond that point.

So note that in this example a 10% increase in head (from 100 to 110%) will drop the flow from 100 to about 65%, the power from 100 to 80% and the efficiency also from 100 to 80% of the maximum efficiency.

On the other hand, an increase in flow from 100 to 120% by reducing the head from 100 to 78% will increase power consumption by about 8% (100 to 108%) but efficiency will drop from 100 to about 88%.

Hope this explanation helps in better understanding the behaviour of centrifugal pumps.

 

[NanoReefWanabe]

and all of the above posts are exactly what i like to see...especially at this point in the day where i feel that i havent learned anything new...LOL thanx for the straightening guys...i always appreciate learning new stuff

BTW...i wasnt saying that is how things are, but rather was my understanding of things as i saw them....and once again appreciate my ignorance being not only highlighted...but rather...being educated...