I'm going to be converting my sprinkler system from black polyethylene
piping to pvc. I thought I recalled hearing that one of the advantages
of pvc is that one diameter of piping is used throughout, usually
3/4", as opposed to the black poly that decreases in width the further
it gets from the pump. But an associate in a store told me today that
the same method is used for both: start out larger decrease as you
go.

There are 3 zones with 12 - 15 heads on each zone, with some in each
zone being 1/2 heads. The pump is 1 1/2 HP.

Will one approach yield better performance than the other?

Thanks.

On Jan 30, 1:43*pm, wrote:
I'm going to be converting my sprinkler system from black polyethylene
piping to pvc. I thought I recalled hearing that one of the advantages
of pvc is that one diameter of piping is used throughout, usually
3/4", as opposed to the black poly that decreases in width the further
it gets from the pump.

The amount of water that can move through the pipe is a function of
the pipe size and will be basicly the same with either pipe
material. The PVC could move more water because the connections/
fittings go on the outside of the pipe, where with poly you use barb
style fittings, which reduces the pipe diameter at that point.



But an associate in a store told me today that
the same method is used for both: *start out *larger decrease as you
go.

That rule is generally true for any water supply job. However,
whether you can live with one size depends on how many zones you are
going to run at the same time, how long the runs are, how many gpm the
heads are, etc. If you have a small system with 3 small heads per
zone, only run one zone at a time, you could use 3/4" for the whole
system.




There are 3 zones with 12 - 15 heads on each zone, with some in each
zone being 1/2 heads. The pump is 1 1/2 HP.

Will one approach yield better performance than the other?

Thanks.

If you google a bit, you can find irrigation suppliers or
manufacturers that have some online tips and layout tools that will be
useful.

Before you start, why do you want to convert it to PVC? The black
poly pipe is used because it's well suited to the application, ie it's
reasonably flexible, can be run around curves, fastens with hose
clamps, is cheap, etc.

I

On Jan 30, 2:51*pm, wrote:
If you have a small system with 3 small heads per
zone, only run one zone at a time, you could use 3/4" for the whole
system.


I should have mentioned that the heads are "mist" heads not large
impluse or rotating heads, and the zones are run one at a time. Thanks.

On Jan 30, 11:43*am, wrote:
I'm going to be converting my sprinkler system from black polyethylene
piping to pvc. I thought I recalled hearing that one of the advantages


There are 3 zones with 12 - 15 heads on each zone, with some in each
zone being 1/2 heads. The pump is 1 1/2 HP.


Toro's website used to have a pretty good section to help you design
your own system. Haven't been there in a while.

Basic process is to lay out your heads and figure out the GPM
requirements. You also need to know what GPM your source can supply at
the PSI required to pop up the heads reliably. The size of the pipe
also factors into what flow you can deliver at what pressure. Then you
partition your heads into circuits so you don't exceed the supply GPM
on each circuit.

GPM = flow in Gallons Per Minute
PSI = pressure in Pounds per Square Inch

Maybe your existing setup can deliver the flow at the necessary PSI to
operate reliably with no changes except changing to 3/4 PVC, but it
wouldn't hurt to spend an hour or 2 looking at the numbers to avoid
unpleasant surprises down the road.

Jerry

Thanks for the good suggestions.