Irrigation Equipment - Sensors

The ability to water only when necessary is the ultimate goal of efficient irrigation scheduling. Today’s technology allows for installation of sensors that can measure soil moisture, rainfall totals, and even shut systems down in freezing weather.

The technology of sensors is quite simple, they interrupt the electrical flow from the controller that would otherwise activate the valve. The sensor does not interfere with the controller’s program and therefore the controller doesn’t know that watering is not taking place. As a result, no "make-up" watering is done if a scheduled watering is interrupted or deleted all together by the action of a sensor. In some cases, for example, systems for large commercial and golf course sites, the controller actually interfaces with the sensor and directly modifies the planned watering schedule. However, that technology has yet to be offered in residential controllers.

Rain Sensors: These units are mounted in a location exposed to normal rainfall, but outside the watering spray of the sprinkler system. There are different designs, but most have settings that allow some sort of measuring to take place. Rain will cause the system to remain off during or after an event if sufficient rainfall is measured. The settings can be adjusted so that a light shower will not effect the system operation, or eliminate a scheduled watering, when rainfall is not sufficient to make up for a normal application.

Freeze Sensors: This type of sensor is very popular in commercial settings, where ice on walkways or streets can cause liability. Freeze sensors can have a place in the residential garden as well. Watering before or during heavy freezes can create problems with ice laden shrubs and trees, as well as creating the same liability concerns the commercial user experiences.

The freeze sensor is mounted on an outside wall, in a location most likely to experience freezing conditions. It will interrupt the signal to the control valves when temperatures fall below freezing. Once conditions improve, the system will return to normal operation.

The most important thing to remember when dealing with sensors is that they are mechanical devices, monitor and adjust them to help conserve water.

Irrigation Equipment Sections
[Controllers, Timers, Clocks] [Heads] [Valves] [Drip Irrigation] [Sensors] [Backflow] [Chemigation]

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