SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Quoted from "gr0d"

Quoted from "Wet_Boots"

Put a pressure gauge on that zone. Get some caps (or plugs) and rework the test zone to have as little as one head spraying. You want to have at least 40 psi in that zone.

Once you see 40-50 psi sprinkler operation, you can have a proper idea of the actual flow you have available.

Is there a backflow preventer in place yet?

Hey guys, sorry for the long delay. It's been a long winter and haven't really been thinking about the system lately. However, the weather might break sooon, so looking to get things going again. I already have a backflow preventer in the system. The GPM and PSI was taken at the main valve box via the boiler drain I setup to drain the system.
I like the idea of the hunter prs40, it seems like that should do the trick with no thinking. What do you all think?

Can go wrong with the prs40 and Mp rotors. They are kinda hard to mess up.

Quoted from "Wet_Boots"

Put a pressure gauge on that zone. Get some caps (or plugs) and rework the test zone to have as little as one head spraying. You want to have at least 40 psi in that zone.

Once you see 40-50 psi sprinkler operation, you can have a proper idea of the actual flow you have available.

Is there a backflow preventer in place yet?

Hey guys, sorry for the long delay. It's been a long winter and haven't really been thinking about the system lately. However, the weather might break sooon, so looking to get things going again. I already have a backflow preventer in the system. The GPM and PSI was taken at the main valve box via the boiler drain I setup to drain the system.
I like the idea of the hunter prs40, it seems like that should do the trick with no thinking. What do you all think?

You should be fine with four i20 on a zone.

However you thinking is a little off when it comes to nozzles. The idea of the system is not to just come on but to water efficiently.

What I mean here.(just an example) the hydraulic calculations may very what nozzles you use
Example :
90 degree rotors should be 1gpm
180 degree rotors 2 gpm
360 degree rotors 4 gpm

The theory here is that it takes twice as long to make a pass for 360 as it does for 180 degree.
If you use all the same nozzles the corners and sides will have much higher precipitation rate than the center.
When you set a rotor from 90-360 degrees the rate that it rotates does not change.

Or you could just uses Hunter PRS40 heads and Mprotor nozzles. Then there is nothing to figure out.

Put a pressure gauge on that zone. Get some caps (or plugs) and rework the test zone to have as little as one head spraying. You want to have at least 40 psi in that zone.

Once you see 40-50 psi sprinkler operation, you can have a proper idea of the actual flow you have available.

Is there a backflow preventer in place yet?

Quoted from "gr0d"

So I went ahead and mocked up one zone with 1" pipe and 4 Orbit Heads that I bought from lowes just to make sure that my design looked good. I used pvc and connected the 3/4" female inlet head to a female 1"x1"x3/4" femail tee via a male 3/4" adapter. I got decent coverage but not as much as I expected using the 4gpm nozzle. I was only getting around 27 feet. I was wondering If I need to step down the inlet pipe to the head to get better pressure? Am I way off in my thinking?

Overthinking can cause lots of problems.

1 - you have 30' spacing. The head of choice would be hunters mp rotator in the 30' class. Look them up. No gears and very little to go wrong.
2 - make sure you use the mp40 sprinkler body with the nozzle. They are regulated at 40psi which is ideal for this nozzle. When you use a regulated sprinkler, you insure that the pressure is even to every head across the entire line.
3 - when you use gear drive rotors, it's nearly impossible to get matched precipitation between full and part circles resulting in uneven precip rate. And nozzling down will affect your radius on the corner heads resulting in uneven coverage. Issues that can be avoided using mp rotators.

Do your homework and check these heads out. Your situation is ideal for these heads. Also, a high precip rate is rarely a good thing so don't look for a head that can really sling the water out.

sprinkler is one of the most useful lawn sprinkler systems, which offers
a number of benefits. All living landscapes need sufficient water to
flourish and survive properly, and relying on rainfall completely is not
quite feasible as that is not guaranteed.

Use the same point for all your supply pressure readings.

Quoted from "Wet_Boots"

Yes, you are way off in your thinking.

It is now safe to assume you have overdrawn your account, so far as pertains to system flow. Remove all the nozzles and try a size smaller. That would be two 3 gpm nozzles for the middle heads on a zone, and two 1.5 gpm nozzles for the end heads. (since we are assuming you now are using 4 gpm and 2 gpm nozzles)

Before doing anything, take more pressure measurements. Again, with the system off, and then, with the zone turned on.

okay, I figured as much. What's the easiest way to accomplish the pressure test withthe zone on? I have a boiler drain after my manifold for draining purposes. Can I check static pressure there with a pressure gauge and test it there as well while the zone is on?

Yes, you are way off in your thinking.

It is now safe to assume you have overdrawn your account, so far as pertains to system flow. Remove all the nozzles and try a size smaller. That would be two 3 gpm nozzles for the middle heads on a zone, and two 1.5 gpm nozzles for the end heads. (since we are assuming you now are using 4 gpm and 2 gpm nozzles)

Before doing anything, take more pressure measurements. Again, with the system off, and then, with the zone turned on.

So I went ahead and mocked up one zone with 1" pipe and 4 Orbit Heads that I bought from lowes just to make sure that my design looked good. I used pvc and connected the 3/4" female inlet head to a female 1"x1"x3/4" femail tee via a male 3/4" adapter. I got decent coverage but not as much as I expected using the 4gpm nozzle. I was only getting around 27 feet. I was wondering If I need to step down the inlet pipe to the head to get better pressure? Am I way off in my thinking?