Calculating pressure - come on in math nerds

[meby]

I'm thinking about sticking a 1000 gal. water tank that I have up in the air as a supply tower for water lines through my pastures for my cows. What kind of pressure would I see if I stuck the tank on 15' poles (that would put the top of the tank at 20') and assuming the tank was full? The outlet on the tank is 2" in diameter and I plan on running 1" black plastic lines through the fields starting at ground level. From the tank location the line would tee. One direction would be approx. 1000' long and the other 500' long for 1500' total.

At its peak it would need to supply roughly 40 head of cows. I know I could just put in a booster pump, but I like the idea of having a 1000' gallons in reserve in the event of a power outage. Obviously given my northern climate, this only functions during non-freezing weather. Is 20' enough head given the amount of lines I need to run? The 1" lines would have the same elevation as the ground where the tank would sit.

Thanks in advance.
-Matt

[dazedandconfused]

Well at 20' you have 46 feet of head or 8.66 psi. At 15' elevation you will have 35 feet of head and 6.5 psi. With out knowing the flow in G.P.M. I can't do the rest of the math. I'd use class 200 PVC like in a irrigation system because you will have less of a P.S.I. Loss due to friction.

Edit.
Here is an example for ya. At 10 G.P.M threw 2" class 200 you will loose .07 psi in 100 feet from friction. At the bottom of that 20' you would be at 8.653 psi. If I had actual gpm I could figure out what your psi would be on the ends. I'd also need to know how much water your emiters would put out and number of each in the pipes. It would be easiest to hook up a small 1"gas powered water pump.

[ahale2772]

UGH i took fluids, failed it the fist time , squeeked by the second, you need to use the Bernoulli equation.

but im not a mathnerd, and Dazedandconfused is correct, I thinkin your missing some numbers

you need definite numbers of either the length of pipe, or the height of the tower, preferably both. of course the water will flow less if the water level is low.

ive been drinking beer and eating cinese food, pretty much usless. Ill try to do the math tomorrow when I'm at work doing nothing for 8 hours

[dazedandconfused]

I do this for irrigation but I usually have a set psi at a level. The psi at the T will only drop out to the end of the lines due to friction loss.

[1STGENFARMBOY]

Meby...what are you wanting to do preshure wash-em or water-em.

i have used a 55gl barrel in the bucket of a tractor with a 100 ft hose and it hase a supprising amount of
head with only 8 ft of drop.

i can't think of a reason it won't work on a float system in a bulk tank just to keep it toped off.

as far as having head psi why would you need anything over 1 or 2 pounds of preshure.

i don't know i'm just asking.

the only thing i know is if your holding tank was only 15 ft higher than your bulk tank the water would run
into it even if it was a mile away.

or is there something i'm missing.

Dar

[dazedandconfused]

It's all about friction loss and gallons per minute with irrigation even gravity fed into soaker hoses. Every pipe size and material has different friction loss. If it's just running out to a ball valve to fill a feed tank it should be ok as long as the pipe is feeding into the top of the feed trauth and has no preasure coming from the opposite side. If it was at 8.653 psi at bottom of drop and 1" feeding out to 1000' preasure should be 5psi. I'd bring the pipe down and 3 it then put a ballvalve on each side of the T to run one side at a time. I know 550 gallons with 7' of head will not gravity feed out of 200' of 3/4" hose.

[1STGENFARMBOY]

man Andy....i just can't wrap my simple mind around water not flowing out of a non obstructed
hose if the sorce is above it, no mater how far away the exit is.

after all some of the roman aquaduct's went for 30 miles with a rough stone wall and only 1 inch of drop in
every 350 ft.

but then again i don't know jack about the subject.

Dar

[dazedandconfused]

I would have never believed it about that tank and hose if I didn't do it myself. From my limited understanding of fluid hydraulics there is allot more friction in pipes then we think. I set everything up in our parking lot to water off the trailer and ran my hoses out. I never got water out of the end of those hoses at 200'. I hooked my little gas pump up and still didn't have much preasure out the end of the hose. Now if you can maintain a constant drop preasure will be higher. We aren't talking about huge heights gravity feeding from. This is just my personal experiences and what I've learned threw irrigation. I have a sheet that tells me flow velocity for Class 200 depending on size and gpm. Also shows friction loss from 3/4" up over 3" I believe.

[1STGENFARMBOY]

It even looks like to me after the hose got full of water it would syphon it out.

thats the difference between somebody thats had the schooling and a goofy
farm brain.

I guess thats why theres a 2,500 hp electric motor and pump every 10 miles
from central ILL to the gulf.....to push the crude oil, evedently it wont syphon.

Dar

[dazedandconfused]

Now threw a bigger pipe it may have gravity fed for me I don't know. It blew my mind it wouldn't do it. I installed a 1" 4stroke gas pump from Harbor feight and it has enough Head now to run 400' of hose and 4 oscillating sprinkler heads. I use it to water areas I can't get to and fill gator bags.

[meby]

Farmboy, the reason I was wanting somebody to do the math for me is what dazed and confused was talking about: friction in the pipes. I was looking at this website http://www.engineeringtoolbox.com/pvc-p ... d_802.html and based on the pvc friction loss charts, the pressure would be overcome by friction before I made it to the end of my 1000' pipe.

I would use a low pressure float valve in the stock tank.

I guess I could install the setup and see if it works. I own the tank and can get the poles to make the tower for free, so it wouldn't cost much to experiment. In a worse case scenario, I just hook up the lines directly to the well and install a booster pump.

-Matt

[dazedandconfused]

Matt you could always keep the line off the ground and give it a couple inches of drop to the tank.

[Richie O]

There must be a way to get it to 1000 feet. I just put in a water line to a house that was 500 feet long from the main and that main is fed from a water tower a few miles away. They still have 90 psi pressure after all that. Maybe the bigger main is how its done.

[dazedandconfused]

It's all about sizing of pipe and how high the water source is from what your feeding. Usually a water tower around here is a couple hundred feet tall. If it's 350' for instance that's 151.55psi without figuring friction loss. You loose a ton of friction threw pipes.

[PToombs]

The bigger the pipe, the less friction. If you use 3 or 4 inch you'll have lots of flow at the end. We ran a 2" water line over 500 feet once. (can't remember exact distance) The water flowed out at less than 1/2 a pipe at the end. It was ok as it came from a spring and fed a holding tank, then got pumped into a house from there. The tank had an overflow line, so the water moved constantly. This was about 30 years ago, So I'm guesstimemoryizing how much came out. I know it was 2" pipe though and the water flowed way slow.
Another thing I rember my ex-boss talking about was a Ram. It was a gravity water pump thinger. It was shaped like a hot air balloon, water ran into it, then when it was full, a valve opened and it dumped out, pushing water down the line. Pretty cool, an early, simple water pump that needed no power.