Peppie
Well-known member
How far away from the return pump can I place a 90deg. elbow fitting?
Return Pump Cavitation
- Thread starter Peppie
- Start date
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I don't see why you wouldn't be able to put it right on the pump, if need be. just saying I think you can put it anywhere. the way I look at it as a plumber: larger water lines in a house have very tight turning 90 elbows, with water pressure up to 80 psi. with a return pump, its always open, constantly pumping water therefore not really building pressure.
Peppie
Well-known member
I want to place the elbow on the inlet side of the pump. The exit side of the pump will be straight up pipe for approx 2'.
Scooterman
Well-known member
No not recommended!
Every elbow, every connection, every inch produces restrictions. Your inlet should be open and clear as much as possible. I've had several manufacturers warn about this. That said, there are work arounds, what pump, what size inlet and outlet, how close are you talking about?
Agreed, I had a pair of OM 4-way's water hammer on account of the 90's being too close to the unit despite being near 20 feet away from the pump. Water pressure and turbulence is not toyed with regarding high flow pumps.
Peppie
Well-known member
Maybe this will help explain what I am looking to find out. I know I can not have the 90deg elbow close to the inlet of the pump. How far away do I need to place it so that the pump will not have cavitation?
blk822822
It's only money, RIGHT?
A 90 elbow can cause up to a 50% restriction. I work on air brakes and we try not to use 90's unless you have to......just due to the restriction. And on a suction side you need as little restriction as possible so the pump dosn't starve. A restriction will make the pump run harder and pull more amps and that cost more in electricty , life of the motor and more heat into the tank.
Peppie
Well-known member
So then I cant have any bends on the pvc line that feeds my CL pump??
Peppie
Well-known member
Should I use spa-flex directly from the DT drain to the Hammerhead pump, with no fittings? This will be for a CL incorp. a OM.
blk822822
It's only money, RIGHT?
Flex pipe is way different....it's a smooth flow. A 90 is like hitting a wall and then having to turn and causes turbulance. Theres the white flex pipe you can get at the hardware store and I beleive you can use the same solvent on it as regular PVC.
Scooterman
Well-known member
What is the inlet threaded size? If you enlarge your inlet that may work, where are you getting the inlet supply? From what source?
Peppie
Well-known member
Inlet supply will be from the DT @ 1.5 '' strainer. This is for a CL system.
I can step up the inlet supply from 1.5'' to 2'', but the inlet to the pump is only 1.5'' So at some point I would have to reduce the 2'' back down to 1.5''
Scooterman
Well-known member
The CL makes a difference also, I think your ok as drawn, your sucking straight from the DT so unless the suction is close to the top it shouldn't be an issue, just put it deep.
kpiotrowski
Kevin
what version of the OM did you run? was it where only one outlet was open at a time, opposed, or in succesion?
Peppie
Well-known member
Thanks Scooter.
I will not use any 90s and will keep the bend as far away from the inlet of the pump as possible.
Spinner
Reef
I would use spa flex if its an option for you, but to answer your question some say 10x the size of pipe feeding pump before 90s. So 15" with 1 1/2" and 20" with 2"?
Peppie
Well-known member
I can always squeeze in a couple more inches. I think I will also order up a few 90 sweeps. That should help, along with the spa-flex.
Didn't matter. Used two different drum versions and the result was the same. Paul at OM and I spent several hours on the phone trying to figure out the cause. The customer service he provides is very good. I will always recommend any of his products to anyone wanting a CL on a large tank
kpiotrowski
Kevin
was the closed loop drilled or an over the top mounted type. very curious as to what to avoid with mine.
I wouldn't worry about it. These 90's were right in front of the OM intakes and the water hammer was a very rare (if not unheard of) case I've used them over the top and drilled with no problems. You should be fine. Lets not high jack the OP's thread anymore. This is about cavitation on the intake of a pump, not OM 4-way do's and don'ts.
Peppie, since the spa flex comes in a roll and is actually a bit difficult to straighten, I'll bet you can easily plumb it in without a 90 at all in the 14" of space you have
