You are not logged in.

Dear visitor, welcome to SPRINKLER TALK FORUM - You Got Questions, We've Got Answers. If this is your first visit here, please read the Help. It explains how this page works. You must be registered before you can use all the page's features. Please use the registration form, to register here or read more information about the registration process. If you are already registered, please login here.


Senior Member

Posts: 21

Location: USA


Monday, December 24th 2001, 10:08am

Measuring Distance

When I look at specifications on throw distances of sprinklers, I'm
a little confused if they are talking about (thinking in terms of a
right triangle) the distance in terms of the hypotenuse or the cosine
(normal horizontal ground measurement) with respect to the angle set by the sprinkler rotor's valve angle. Is their some general rule to follow with respect to knowing the sprinkler's horizontal area of coverage; rather than having to break open my old physics books and factor in parameters such as spray angle, nozzle pressure, ect.....
I want to use a Hunter I-20 rotor throwing at 16 feet. Also, do
these spray distances apply to spray sprinkler systems (horizontal


Posts: 60

Location: USA


Wednesday, December 26th 2001, 9:54am

The radius of throw of a rotor or spray head is measured in feet and describes the distance the water will be thrown forward, away from the sprinkler head itself. Anotherwords, if the I-20 rotor specs state that the radius of coverage is 17' to 47', that means the furthest distance the water will be thrown will be 47' and the shortest distance will be 17' feet. The different distances or radius are achieved by installing smaller or larger nozzles into the rotor head (complete nozzle sets come with each rotor) and by turning down or up an adjustment screw on the rotor head.

The Arc is the amount of a circle that the rotor will rotate to provide coverage ( how much of a circle is covered by the rotor spray). The arc is very simple to increase or decrease. The left or right side of a rotor, depending on which brand you choose, will be the fixed side that you line up with the boundary (sidewalk). You can then use the adjustment screw on the rotor to open or close the arc thus increasing or decreasing the degree of a circle covered.

I do not suggest you use an I-20 rotor for throwing 16 feet. You should use a rotor that is designed for that small of throw, Hunter PGM rotor or Rain Bird 3500 series or 5004 series rotor. The I-20 would have to be turned down too much which would mess up the uniformity of spray.

For more on radius and arc adjustments see the following link on our website for the I-20 rotor:
<img src=icon_smile.gif border=0 align=middle>

Rate this thread