For the Smartline controller, one of the most important factors is the sprinkler type. This may seem like a quick, glance-over setting, but it has a huge impact on the performance of the controller.

### Defining “sprinkler type”

What does “sprinkler type” truly mean? Well, the controller looks at sprinkler type as how fast the water is being applied in the zone. This is called the precipitation rate (precip rate), some also call this the application rate. Professional Irrigators call it the precipitation rate and that is the term we will use.

The precipitation rate is recorded in “inches per hour”. This is how many inches (or fractions of an inch) are applied in 60 minutes of operation of the zone. The reason the controller looks at inches per hour is because the deficit is calculated in inches, so going back to high school math, we need common denominators to complete the equation.

### How does precipitation rate work?

The precip rate for a zone is 1.5”/hour. This means that after 1 hour of run time, that zone has applied 1.5” of water to that zone. If the zone operates for 30 minutes, then the total application is 0.75”.

The precip rate is directly proportional to the run time a zone runs when applying the needed inches to the landscape. If the programmed precip rate is too high, the plants will not get enough water as the run times will be too short to accurately apply the correct amount. If too low, we overwater.

### Determining the precipitation rate for a zone

Use this simple equation:

A = gpm for a full circle nozzle. Most spray nozzles are 4 gpm for a full circle

We have 15x15 square spacing, so our precip rate is =

### The easiest way: sprinkler type defaults

Smartline was developed to make this easy for you to program by giving the user the option of choosing default settings or imputing specific precip rates. Below is the excerpt from the Smartline manual detailing the setting for the defaults:

These precip rates are good averages, but do not always represent the actual precip rate for every zone. We recommend if you are having trouble with too much or not enough water to do the calculation above and compare.

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