Water
Pressure
From: Samba (das) SDG (Mauritius)
Samba.SDG@bbt.se
Sent: 22 December 1999 11:53
Subject: Water Pressure
[Text 2876944 from COM]
Can anyone out there tell me how to calculate water pressure?
I am about to install a 4000 litre water tank on top of a pile of rocks, at
about 10 feet higher than the highest point on our land. This will be fed by
a windmill that pumps about 500 gallons a day.
The tank will be connected to a 35mm plastic pipe about 290 feet long. At
either end of this pipe and at its center I will connect 25mm pipes, which
will flow down a slight gradient, and the pipes will be around 150' long
each. These 3 pipes will be punctuated by click connectors every five feet
or so, to which we will randomly connect 1/2" hoses as and when needed to
service the beds. The hoses will have a maximum length of 120 feet (probably
two 60 foot hoses with a joint, as we do not always need such long hoses for
all places).
At any one time, maybe four or five hoses may be going, at any place in the
lines.
Does this sound like a good arrangement?
I need to know if I need pressure hose and pipes, and if so, what gauge?
We would do the whole thing with Bamboo pipes, feeding troughs at the ends
of the beds and then use watering cans, or even punctured bamboo (as drip
irrigation, but I am not sure if that can be done), but this would take a
lot more time, and we need to get a lot of things going asap, so we can
survive.
If no one has the time to work this out, please let me know how you
calculate water pressure.
Thanks
Your Servant
Samba das
From: Madhava Gosh (das) ACBSP (New Vrindavan - USA)
Madhava.Gosh.ACBSP@bbt.se
Sent: 22 December 1999 15:16
Subject: Re: Water Pressure
[Text 2877396 from COM]
I need to know if I need pressure hose and pipes, and if so, what
gauge?
Certainly Carol is the authority on this issue. Just some thoughts. The
higher the fall, the greater the pressure. If you are only ten feet above
highest point, you shouldn't have to worry about too high pressure on only 2
acres, unless they were virtually cliff side. The greater concern than
pressure will be traffic over the pipes.
Where they are developing springs on NV property, if they is only animal or
light traffic over collection lines, they use corrugated pipe, but switch to
schedule 40 where there will be routine tractor traffic. It matters if you
are burying the pipes or not, what kind of traffic will be going over them
etc, more than the water pressure that you should be concerned about, IMHO.
Managing which outlets are open will have some importance when watering, as
you will get greater flow at the lower elevations then the higher ones. I
have a spring about 10-15 feet above one garden. It does about 50 to 200
gallons a day. I run it down to the garden in several hundred feet of garden
hose. It flows with very low pressure, more would be better. I can only put
one dripline on it at a time. It collects in a 400 gallon tank, that usually
I let fill up and then flow out all at once, get better distribution through
he driplines that way.
With your 1.5 inch line, you will get better flow, then my small 1/2 inch
line garden hose, plus you may have a short run of pipe.
We would do the whole thing with Bamboo pipes, feeding troughs at the
ends of the beds and then use watering cans, or even punctured bamboo (as
drip irrigation, but I am not sure if that can be done), but this would
take a lot more time, and we need to get a lot of things going asap, so we
can survive. If no one has the time to work this out, please let me know
how you calculate water pressure.
Thanks
Your Servant
Samba das
From: Carol
DGilsen@aol.com
Sent: 22 December 1999 21:21
Subject: Re: Water Pressure
[Text 2878235 from COM]
Haribol to All
You won't need high pressure hose or pipe unless the pressure exceeds 120
psi. you won't need them then even unless their is a pressure vessel
involved. Easiest way is to have a float valve in your tank when the tank
volume reaches a certain point it starts to drain to your irrigation
system. No pain or hassle you just have to move the hose around or open
and shut valves.
To get the fall (pressure of the amount of water from highest point to
lowest point) is Height(H) or head of in feet Pressure (P) in LB per sq.
inch
Head pressure=.43xH
Plastic pipe will work in most irrigation systems. No sweat unless you
have a two hundred foot slope over two acres. Even then don't sweat the
small stuff.
Carol
Sent: 24 December 1999 11:07
Subject: Re: Water Pressure
[Text 2881705 from COM]
To get the fall (pressure of the amount of water from highest point
to lowest point) is Height(H) or head of in feet Pressure (P) in LB per
sq. inch Head pressure=.43xH
Hmmm. I am a bit stupid when it comes to calculations, and I don't quite
get this. Does this mean that if the base of my tank is 10 feet up in the
air, then the pressure I get at ground level is 4.3 psi?
What about the dimension of the tank? I mean if the tank is 10 feet high,
and 6 feet across, or 10 feet across and 6 feet high, does that make a
difference?
Then what about pipe pressure ratings? Here they quote them as pn or is it
pu. What does that stand for? Some people have pipe at pu 19, others at pu
3. Which is the higher pressure? (is it like gauge? from my memory the
higher the gauge the thinner the metal sheet).
Enlighten this poor fool please.
YS Samba das
From: Carol
DGilsen@aol.com
Sent: 25 December 1999 03:26
Subject: Re: Water Pressure Not a big deal
[Text 2883099 from COM]
Samba old boy Haribol
You are not alone many people have problems with water related issues.
First of all, what are you trying to determine? Water pressure is
determined by the weight of the water. The higher the water tank the more
pressure. The bigger the supply pipes to your garden the greater the
volume your garden gets, simple. Now (don't let this confuse you) the
smaller the pipe the greater the pressure. Remember big supply pipes
provide lots of water, but not much pressure. Small pipes supply lots of
pressure (thumb on the end of the pipe to make it squirt further) but
there isn't much volume. To get lots of fall (pressure) put your water
tank up as high as you can get it. That is why American municipal water
supplies tanks are on hills or towers so the city gets high pressure by
gravity. This is not rocket science. In the USA water pressure is
calculated in PSI pounds per square inch of volume. Sea level is the base
line. For two acres put your water tank ten feet or 3 1/3 meters above the
lowest point on your land. That way every thing is gravity fed. You don't
have a freezing problem do you? if not you are set. A wind mill can pump
the lake water if you are on the bank of the lake. If not you should be
able to hand dig a twenty or thirty food deep well. Its not as tough as
you think. A gasoline powered pump like they use in Indian rice paddies
can pump a tremendous amount of water in a short amount of time. Talk to
those wonderful farm agents the government provides for free. Who knows
they may provide you with a free pump. I got a replacement fan for my
windmill for free once from an agent who knew someone who had
"modernized." Those guys are full of all sorts of really neat information.
Use them whenever possible.
Carol
From: Mangal Artika (Dasa) HDG (Washington - USA)
mikep@localaccess.com
Sent: 03 January 2000 05:48
Subject: Re: Water Pressure
[Text 2901395 from COM]
On 24 Dec 1999, Samba das wrote:
To get the fall (pressure of the amount of water from highest point to
lowest point) is Height(H) or head of in feet Pressure (P) in LB per sq.
inch Head pressure=.43xH
Hmmm. I am a bit stupid when it comes to calculations, and I don't quite
get this. Does this mean that if the base of my tank is 10 feet up in
the air, then the pressure I get at ground level is 4.3 psi?
This is correct, but it also means that if you drop down the hill another
10 feet in elevation to you outlet in the pipe you will pick up another
4.3psi minus any loses in the pipes.
What about the dimension of the tank? I mean if the tank is 10 feet
high, and 6 feet across, or 10 feet across and 6 feet high, does that
make a difference?
The volume of the tank doesn't make any difference in the static pressure
at the outlet.
Then what about pipe pressure ratings? Here they quote them as pn or
is it pu. What does that stand for? Some people have pipe at pu 19,
others at pu 3. Which is the higher pressure? (is it like gauge? from my
memory the higher the gauge the thinner the metal sheet).
Most pipe will come with the specs. printed on the side if not ask your
distributor.
Your Servant
Mangala Artika Dasa
