It is likely to be the same energy loss as if placed on the outflow. If the water pressure is too low and the pump too strong you could get cavitation. Cavitation may eventually destroy the pump impeller or burn out the motor. Cavitation is unlikely if the pump is below the sump water surface elevation.
Idea to reduce head height, alternative to 90° elbow
- Thread starter TheFishTeen
- Start date
wayne in norway
New member
As I recall Delbeek and Sprung Vol 3 has a table of pipe fixtures like bends, at different diameters, and their respective values for head loss. Have you looked at this?
These hydraulic formulas for common fittings are well established and published in many places. You don't need to buy a book to find them although it is nice to have a book you can trust.
Pumps can't be expected to perform at exactly the published efficiency since voltage and manufacturing vary. Encrusted pipes and impellers will have a reduced flow. The loc line nozzles that are commonly used will also affect the flow but as far as I know nobody has a formula for those. Smaller pvc pipe varies some on the inside diameter and roughness. You may add a reactor to the return pipe in the future. All of these reduce the value of performing complex calculations when you really need to oversize the pump anyway.
I was thinking I might try to figure out what a good rule of thumb might be but I don't want to spend the time on it if someone already did it.
I hope I am not taking your thread off subject Fish Teen. If you know approximately what your flow rate is and the inside diameter of your pipe you could post it and someone will probably help you calculate the theoretical difference in head loss between a short elbow and a sweep.
Pumps can't be expected to perform at exactly the published efficiency since voltage and manufacturing vary. Encrusted pipes and impellers will have a reduced flow. The loc line nozzles that are commonly used will also affect the flow but as far as I know nobody has a formula for those. Smaller pvc pipe varies some on the inside diameter and roughness. You may add a reactor to the return pipe in the future. All of these reduce the value of performing complex calculations when you really need to oversize the pump anyway.
I was thinking I might try to figure out what a good rule of thumb might be but I don't want to spend the time on it if someone already did it.
I hope I am not taking your thread off subject Fish Teen. If you know approximately what your flow rate is and the inside diameter of your pipe you could post it and someone will probably help you calculate the theoretical difference in head loss between a short elbow and a sweep.
TheFishTeen
New member
Thanks for the reminder - I totally forgot about this book. Page 111 in the chapter of Plumbing and Electrical, there are multiple charts and graphs. I will take a look at them now.
uncleof6
Active member
Well except in the case of the person that was using a pressure pump, with 13 - 14' of static lift, but the insignificant friction loss, in the not all that complex plumbing system, brought the total head loss to around 42' vertical lift, just below pump shutoff. Friction loss is more significant that most care to believe, and is a major design consideration in plumbing systems. With the pump choice being the LAST consideration--because without knowing what performance you want, and what the plumbing will do at that flow rate, you do not know which pump will do the job, and you don't know anything that can be related to what flow curves--you can get--tell you.
uncleof6
Active member
Although the ReeFlo Hammerhead is a very strong pump, it does not score best in high pressure situations. I figure I have about 11' feet vertical head and ~17' feet horizontal. I called up ReeFlo, and they said not to figure in the horizontal distance into the total head pressure. So I have 11' feet of head (apparently).
Now with that, I do have 4, 90° elbows needed to get to the tank.
One member here posted that a 90° elbow is the equivalent of 2 feet of head.
So with that fact in place, I have 19 feet of head pressure.
Here's my idea. I have read that Flex PVC is not pressure rated - but then again I have seen countless threads where people use flex pvc on strong pumps.
So, IF flex PVC can be used on the return line of the ReeFlo Hammerhead, I had the idea to replace all four 90° elbows with a graduated bend with Flex PVC, in hopes to greatly reduce the friction against the pump, thus reducing head loss.
So my question is:
Will this method reduce head loss?
Heres what I mean:
On the left is what one turn with a 90° elbow would be like. One the right, is the alternative. I am still making a full turn, but it is dragged out much longer.
Here is the Head to Flow chart via the manufacturer.
Simple answer, no it will not help. Since you are still turning the water 90°, only over a longer distance. This reduces turbulence in the turn, however does not really reduce the friction loss.
Friction loss in fittings is based on equivalent feet of straight pipe, and the charts read per 100 ft for the most part. The rule of thumb for 2" pipe, being one foot vertical for 10' of straight pipe, is inaccurate in that it actually turns out to be 14.26' per 100--and only at one particular flow rate. A 3/4" 90 has a friction loss of 2' of equivalent straight pipe, not 2' of lift (head.) What exactly it would be is a function of the flow rate (water velocity) through the system.
The only things you can do to reduce friction loss in your piping system is increase the pipe size, and swap out 2 90°'s for 45°'s one for one. Static lift will not change, however the friction loss in the two turns will decrease by 1/2, and probably be 1/3 to 1/4 overall what it was with the smaller pipe.
Last edited:
TheFishTeen
New member
Thanks sir.
Following your train of thought, would 3" PVC be pushing it too far? (No pun intended).
uncleof6
Active member
Thanks sir.
Following your train of thought, would 3" PVC be pushing it too far? (No pun intended).
Well I am still editing my post above, (connection problems) however yes, 3" would be pushing it a bit too much-- a simple pipe size larger will reduce it significantly enough. Theoretically, yes, the friction loss would be less, but......
tgunn
Active member
I had the same goal as you so I bent PVC pipe. It was easy.
Out of curiosity, where did you get that nifty spring-bender from?
Tyler
I got it at Mcmaster Carr
http://www.mcmaster.com/#spring-tube-benders/=grlg8y
But after a little practice (like 2 bends) you can do it without the spring, just use some good gloves and massage the pipe while hot.
http://www.mcmaster.com/#spring-tube-benders/=grlg8y
But after a little practice (like 2 bends) you can do it without the spring, just use some good gloves and massage the pipe while hot.
tgunn
Active member
So you didn't have problems hand-bending the tube without it collapsing in on itself? It always seems to collapse when I do it. Perhaps I'm not being gentle enough though.
Similar threads
