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Unread 07-15-2002, 01:41 PM   #15
BillA
CoolingWorks Tech Guy
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Join Date: Dec 2000
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jeez fellahs, its a super simple test yielding an approximation;
no need to try to 'over-engineer' it

"inches of H2O" are very common units used to measure low pressures
and incidentally quite handy if using a water manometer
using mercury will not yield any more accuracy, just accommodates higher pressure
i.e. 21ft.H2O = 18.5in.Hg

bigben2k
take your pump's deadhead pressure, convert the units to in.H2O (or ft.H2O); and rest assured, NO water will come out the top
- well, there is a surge when the pump starts up - so add a foot (or pinch it off)
-- the size of the risers is irrelevant as there is no flow through them

myv65
"The problem with such a simplification is that you may quickly add up total head losses higher than the dead head pressure of the pump."
nope, not if you are referring to the manometer test

"What is more accurate, though not much more difficult is to use tables relating head loss to flow rate and diameter."
this is what Crane No.410 is all about
- but w/o some experience it is indeed easy to have nonsensical calcs

be cool
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