head loss in pipe/hose???

[pHaestus]

Take the 0.5" ID data:

total head loss = loss from tube's length + loss from tube's bend

so ht = hb + hL

ht = Kbv2/g + f(L/D)v2/g

Kb = 42f (tabulated in Crane r/d = 8/0.5 or 16)
L/D = 18/0.5 or 36

ht = 42(v2/g) + f(36)(v2/g)

ht and v are known as is g. Just a matter of plug into spreadsheet and get units right at that point, right?

[BillA]

well, anything can be back-calculated - but I'm not too comfy with 2 aspects:
- the length is quite short relative to the magnitude of the effect/difference, and
- the effect of 'rounding' errors at the low drops is rather large

NOTE: the 3/8 hose is clear vinyl, while the 1/2 and 5/8 are silicone

needed is data from a 10' straight length - but I did not setup to do this
-> my intent was only to provide WCers with some 'plug in' values,
since most hose is actually used in short pieces to make a 90

these curves were generated as an adjunct to my running 'calibration' tests to establish the correction factors for different sized hose connections to the cross used to take the temp and pressure taps

I could back out some connection values also; but as I use Cu thin wall pipe, the numbers would not be too useful

[pHaestus]

All good points. Just looking at the graphs then for most users (1/2" ID and under 2gpm) the contribution is pretty minor anyway.

[BillA]

yup
but the 3 and 4gpm 'dreamers' need to get REALLY serious about each little thing
- or get a nice BIG pump

[bigben2k]

Originally posted by pHaestus
...The proposed calculations in this thread are for the most part noodling by people who would rather spend time doing this than their gainful employment.

Nothing personal, eh?

So what do you estimate the friction factor to be?

[BillA]

I think pHaestus does have a job, academic welfare makework - something like that.

[pHaestus]

It's cheaper to give me a little research money and salary than to turn me loose on society.

[Blackeagle]

BillA,

Thank you very much for that graph, that is just the sort of info I was hope'n for.

I have no doubt I'm one of your "dreamers", but am trying to get a idea of just how large a pump is needed and the head loss that will have to be overcome.

Thanks again.

BE