Golf Course irrigation

[RJG]

hey guys, im designing a new irrigation system for my golf course and im looking for some help. this is a very budget concious system. the system will be an electric valve and hydraulic head block system. The pump station will be at the highest point of the course, the farthest point from the pump station is 3-4000 feet in distance and about 100 feet in elevation change. the are 4-5 holes that are at the same elevation as the pump station, but most of the system is downhill of it. Im going to be running 6" main line. I'm trying to plan the best pump set up for me, due to it being so downhill, i dont feel i need a huge pump station as gravity will do most of it for me. the pump im eyeing is a 6" end suction centrifugal low speed pump that can flow 2000 gallons/min and is 30hp. im planning on making my own pump station, utilizing a CSV and a pressure tank, pressure relief valve and probably a nema 3r control panel. i guess my questions are if im using the right pump? when i've only got one zone turned on, or im using a quick coupler will the csv dial that big pump down enough or should i have a seccond jockey pump as well? the other thing i was wondering about is how to incorporate soft starting onto a pump.

thanks guys for any help, i really appreciate it.
RJ

[RJG]

the other thing im trying to figure out is how small of a pump i can run, the pump i was talking about is 2000 gpm which is more than a 6" csv can handle, and way  more than i even need. maybe i should run a 4" pump? i know its smaller than the main pipe size but once the main pipe is charged 4" should be enough to keep up with everything.

[Cary Austin]

At the bottom of a 100’ of elevation change, you will pick up about 40 PSI.  Most golf course type sprinkler heads require 80 to 100 PSI.  If this is the case you will need a pump that can produce at least 60 PSI.  Those golf course type heads usually put out about 50 GPM each.  So a 2,000 GPM pump will run 40 of them at one time.  Sounds like a lot to me.  I have seen some pretty large golf courses get by with 1,000 to 1,200 GPM.

The right 30 HP pump can produce about 1,000 GPM at 40 PSI.  This would give you 1,000 GPM at 80 PSI at the bottom of the hill.  But it would only give you 40 PSI for the holes at the top of the hill.  So you would either need lower pressure heads, spaced closer together at the top of the hill, or a pump than will deliver more pressure.

You could also do a 60 HP pump that will give you 1,000 GPM at 80 PSI.  Then you will have 80 PSI at the top of the hill and 120 PSI at the bottom.  You could also use a pressure reducing valve to decrease the pressure going down hill if you wanted, so you would have 80 at the top as well as 80 at the bottom.

A CSV will make a 30 HP or a 60 HP pump supply all the water you want, or just a single quick connector by itself without hurting anything.  And if you pick a good pump, the amps will drop by 50% when just running a quick connector by itself.  However, a 3 HP or 5 HP jockey pump is always a good thing for a golf course.  This takes a lot of wear and tear off the larger pump, and saves energy when using quick connectors or just keeping up with leaks.  If you use a 5 HP jockey, you can actually decrease the HP of the big pump by 5 HP as well.  It is easy to make the two pumps work together, even if they are not close to each other, by simply staggering the pressure settings.

We can make this work anyway you want and would be glad to help you.  You should probably call me to discuss this, because believe it or not, pumping “downhill” will be your biggest hurdle.   When you turn on sprinklers at the bottom of the hill, it takes a while before the pumps see a decrease in pressure.  It is kind of like pulling the slack out of a tow chain.  When the slack is gone, the pumps have to play catch up, but not over do it.

Then when you have the sprinklers working and water running down hill, the water doesn’t want to stop coming downhill when you turn off the sprinklers.  You have to make allowance for these things when pumping downhill, so you don’t blow up your pipe and fittings.

I would be glad to help you with these things and can help you pick the right pump(s).
Thanks
Cary
800-652-0207 

[RJG]

awesome, thanks for the help, i will give you a call sometime this week. what you're suggesting is exactly what i've been researching today. the pressure reducing valve sounds like a good idea, also, l plan on using hdpe pipe as well so that should help with the water hammer. the biggest heads i'll be running will flow about 50gpm's at 80-90psi. the smallers heads i'll be using i can dial down the pressure at the valve for that block if i need to. i think a 90psi system with a jockey pump and maybe 1 or two pressure reducing valves as the elevation drops sounds like a good idea.

[Cary Austin]

How many of those 50 GPM heads will you be running at the same time?

[RJG]

Sorry. I meant to put that above, I was agreeing with you on pump flow because there won't be more than 4-5 heads per zone and I don't need to run more than 4 zones at once. So thats be 16-20 which would only be 1000gpms. Honestly I dont even need to run that much at once but id like to have the ability to