90 degree fittings
- Thread starter RonD
- Start date
IE if I could find something like this for better flow
http://www.vacdepot.com/product-info/cisp/images/item/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
http://www.vacdepot.com/product-info/cisp/images/item/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 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
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
NanoReefWanabe
Active member
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*
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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Try flex PVC, much less added head.
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You wouldn't think so but larger pipes will actually add more head. Trust me, I'm an engineer.
http://www.engineeringtoolbox.com/resistance-equivalent-length-d_192.html
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/fluids/calc_pipe_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
http://www.efunda.com/formulae/fluids/calc_pipe_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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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.
You should go back to school, maybe you will actually learn something next time.
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.
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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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.
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.
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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/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.
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.
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
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
This is correct.
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
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.
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.
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
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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!
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!
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)
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.
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.
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
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
