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Unread 05-12-2004, 06:55 AM   #41
Cooling Savant
Join Date: Feb 2003
Location: USA - Boston area
Posts: 798

Originally Posted by pHaestus
...Bill has some pretty good evidence that the Eheim P-Q curves are a bit optimistic. ...
I ran into a pump test on that seems to indicate that Eheim's specs on the 220V 1046 and 1048 are actually a bit conservative.
It's in German/Deutche. If you don't read that, I've used Systran to produce a translated version and put it here. If you want to grab the numbers, here's the raw spreadsheet. I've edited it by removing unintersting-tome pumps and data columns. I may have totally screwed something up in translation - but I've tried not to.
They've got manafacturer's pump-head specs in bar and observed head in m (and I'm assuming that's m/h2o).
They've also got flow measurements for each pump through 2m of various sized tubing. At least I'm assuming that's what the German means.
I'm a little bit lost with converting flow rates at various restrictions into head/flow figures appropriate for a graph. I'm guessing the first step is to convert a liter of water into a cylinder the diameter of each size of tubing. Because the figures are in l/min, I know how long the "cylinder" is that goes by every minute (measured # of liters times length). This gives me velocity, which I can then use to calculate resistance. I'm pretty sure none of these are fast enough to be "turbulent" which means I should be using ??? to calculate resistance (or maybe just look up in a plumbers' table which might have the advantage of being observed data rather than output of a formula). Have I got that approach right? Anyone got a direct conversion formula (I'm just trying to satisfy my curiosity about the HPPS and data on that pump has been very scanty - it's an amazingly quiet pump, BTW...)

Last edited by bobkoure; 05-12-2004 at 06:57 AM. Reason: bad tag
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