Head Pressure Loss

[PDDII]

Does anybody know how to calculate the loss of GPH for a pump? I am considering using a Maxijet 1200 in my sump and pumping up to the tank. I think the 1200 runs about 295 GPH but what would the loss be pumping up for approx. 3'?

Thanks for any help.

PDD

[Biomanjcs72]

SOme manufacturers (I know Rio does) provide graphs that show the different pumping rates and different heights. I'm assuming that the Maxijet doesn't come with such a graph, or you wouldn't have asked the question.

I would say get a bucket of known quantity, or one that's graduated (preferably a few gallons) and "time" the pump on it's fill. Then it's a relatively simple algebra problem.

Where "T" is time in seconds it took to fill container and "Y" is gallons of container.

[ (T/60) x 60] x Y = GPH at that height of your pump.

If you find some sort of pump rate loss to height pumped equation, then just make sure you add the entire length of pipe the water travels through to to tank, not just the height above the sump.

HTH [img]/ubb/smile.gif[/img]

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JCS
Some days you get the bear, some days the bear gets you.

[This message has been edited by Biomanjcs72 (edited 05-14-2001).]

[Doug1]

My Hagen 802 rated at 400gph pumped about 175 an hr at 3' Im guessing return rate on a maxijet wont be a lot [img]/ubb/frown.gif[/img]


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Reef as though your life depended on it, yours might but the seas does
Visit www.thereeftank.com User friendly and flamefree Doug TheReefTank admin

[Rin]

I agree with everything above except for the part about using the length of pipe when doing head pressure calculations.

When using pressure calculators (like Reefcentral's) you can figure out your total loss from the different factors. But the really simple calculators only count the static head pressure--which makes up most of the loss. If you find a simple calculator use the difference in height from the discharge of the pump to the discharge of the return outlet into the tank. Don't use the total length of pipe.

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-Todd
'There're only 3 types of people in the world: Those who can count and those who can't'

[Biomanjcs72]

It is a principal of physics which states that the pressure on a pipe at any given point is a function of the length of pipe (and subsequently fluid) beyond that point. I don't have my physics book here with me at work, or I'd site the equation used. As long as there aren't too many twists and turns in your return, using the height won't throw the numbers off that much.

[Rin]

I'm in total agreement with you on that. Losses in a pipe are much more than just the height difference. It's also friction factor (very small for such short lengths of pipe) and the number of bends, angles, and constrictions.

It's just that the 'simple' head loss calculators don't account for these and if you use the entire length of pipe on these rather than just the height, you'll severely overestimate the total losses (unless your piping system looks like an Esher drawing.)


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-Todd
'There're only 3 types of people in the world: Those who can count and those who can't'

[PDDII]

Thanks for the info. guys.

PDDII