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Water pressure question

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Norm:
To get back to the original question.....

 So, if we took a large diameter pipe, say 4", ran it down the hill to the build site and then choked it off to a smaller diameter, say 3/4", there would be an increase in pressure, no?

Bluntly no....
If you had a garden hose with a nozzle at the bottom of the hill ....turned it on
so it was really squirting out hard enough to knock your socks off   ......
aimed it toward the sky....it could do no more than squirt as high as the top of
the 20 ft. hill ....if you walked up the hill 10 ft. to try and squirt Billy Bob at the
top of the hill with the hose ? ....nuff said   ::)

Norm  :D

solarnewbee:
Having studied hydraulics, water flow and pressure is a hydraulic situation. Pumps create flow and pipes create pressure. This is why homes are Piped 3/4 inch all the way to the area we want to plumb then reduce to 1/2 inch stubbed thru the wall and finally 3/8 to the fixtures .

Reducing down creates the necessary pressure needed at the fixture but larger piping to the general area will allow a high volume of water. Reduction in piping also prevents being roasted by hot water in the shower when someone flushes the toilet that got plumbed with 1/2 inch pipe. American mobile home manufacturers do this commonly (idiot syndrome to save pennies).

As for the well being 20 ft above the home, you would get that extra column of pressure created by gravity if you drilled straight down 20 ft then straight over to house, you may gain 20psi but since your coming down at an angle the column is not affected by gravity the same as a vertical column. I'm sure there's more math involved to find the advantage going down hill from the well. 1" or 4" you'll get the same results when they tie to the 3/4" piping at the house. Better off just running 1" right off the pump unless it's a submersed pump (1 1/4 to 2")then your dealing with head pressure and the pumps capability of pumping against gravity. I have heard that for solar purposes submersibles are a better alternative. They run off 220v and can keep up with those long showers.

For every foot of water column you achieve 1 psi, hence the popularity of water towers. Pumps keep the tank full much easier than pumps trying to keep up with varying customer demand.

Well, hope that clarifies it. Oz make my eyes crossed tho

oztules:
"For every foot of water column you achieve 1 psi,".... hmm not really.

Water only has  Specific Gravity of 1.... so actually 1 foot of  ( fresh) water equates to about .43psi..... so 20 ft of head from our original hill is 8.6 psi etc etc etc.

If we wanted to pretend that 1 ft of water  = 1psi, .... then the waters specific gravity would need to be in the region of 2.3


.................oztules

rossw:

--- Quote from: Solarnewbee on May 01, 2016, 12:03:58 am ---you would get that extra column of pressure created by gravity if you drilled straight down 20 ft then straight over to house, you may gain 20psi but since your coming down at an angle the column is not affected by gravity the same as a vertical column.

--- End quote ---

I think you're dead set wrong there.
The static pressure is a function of the total vertical difference. 20 feet straight down is the same pressure as 20 feet down and 20 feet sideways (ie, 28 feet at 45 degrees).

BUT pressure under flow is reduced by the friction losses, and here the friction losses over 20 feet horizontally at full pressure would be higher than the friction losses of a total of 28 feet of the same pipe, at a 45 degree angle - meaning the angled pipe will deliver more pressure at a given flow rate, than 20 feet down then 20 feet across!

Sasaka-4628:
If it was gravity flow than I would say no but I may be thinking incorrect.

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