Question



   I am attempting to design an irrigation system for a neighbor but before I
even attepmt to lay it out I have some questions as far as water flow and pressure
go.
  For starters when I looked at the pump set up what they have is an inch or an
an inch and a quarter pipe coming straight up out of the pump with
the pressure gauge on top.
 A couple of inches up from the pump they branched
off with polyetelene one inch to the expansion tank and a couple of inches
further up they they branched off with a tee into three quarter flexable tubing
which runs to the house.  ( THE 3\4" FLEXABLE TUBING I'M SPEAKING OF IS BLUE
AND HAS PRINTED ON IT PORTABLE WATER I00 P.S.I. AND 3\4" ALONG WITH A
BUNCH OF MEANINGLESS NUMBERS SO i'M ASSUMING I'TS THE SAME I.D,  AND O.D. AS
ANY POLYETHELENE. )
 At any rate , the 3/4" is all I can see to tap into with a compression tee.
From that point I would travel roughly 25' to the outside of the house , set up
my manifold with my control valves, and run several zones out to the street each
being roughly 100 ft. in length. all 3/4" or would it be advisable to reduce it
to half inch ??
 Now for the actual question.   As for the water flow I did the bucket thing and
came up with 8 gallons per minute.  As for pressure there is a faucet near the
pump and I was told I could screw a gauge on that and that would be sufficient.
But when I went to http://www.irrigationtutorials.com/sprinkler04.htm
he recommends this elaborate system with 8" pieces of pipe a ball valve , a pressure
gauge and  a five gallon bucket with a whole long procedure. so I'm confused.

   And finally , with the sytem I explained above and the 8 GPM ,  WHAT WOULD
AN SUFFICIENT WATER PRESSURE BE FOR THE 100' RUN I SPOKE OF.

   Hope I did not give to much or to litlle info. I  would not blame you if
you did'nt answer.  I don't think I would take your job even if they paid me, ha ha

ANY INFO APPRECIATED

    MIKE

Answer
Wow.  Thats a lot of question.  Be very careful when tapping into someones domestic water source for irrigation.  It is easy to create a backflow condition that will contaminate the domestic water.  That said, you are going to have to carefully consider the amount of water demand that each zone will have.  8 GPM is not a lot, so you need to stay below that figure in your system demand.  Worry more about demand than PSI.  Stay with larger pipe.  And keep your zones at or about 7 GPM.