Irrigation Controllers – Current Projects

Rain Sensor Protocol Testing

Sponsor: Various Manufacturers

Timeline: 6/2010 – 5/2011

Abstract:

Rain sensors (RSs) appear to be a useful tool for water conservation at residential and commercial sites. However, little evidence related to RS performance and/or reliability exists. Testing of RSs against a standard procedure with respect to the rainfall depth before RSs switch to interrupt mode, and the accuracy, precision and variability of their set points will provide the needed data and evaluation to establish performance characteristics.

Testing of severarl sensors will be performed as specified in the Irrigation Association (IA) Smart Water Application Technologies specification

The units to be tested will be purchased from an irrigation dealer, and installed and set by University personnel. Every sensor will be placed in the same testing area at the testing facility. Each RS model test will require eight identical devices, which will be connected to a datalogger. Each time a rain sensor changes status (from allowing irrigation, to interrupt mode, or vice versa), the date and time will be automatically recorded. Each set point test will be repeated eight times to determine the variation inherent in individual sensors. Relative humidity, incoming solar radiation, and temperature data from a nearby weather station will also be collected. The standard test will use a rainfall simulator to allow faster data collection under controlled and uniform rain events.

Testing will begin June 2010 and continue through May 2011. It is anticipated that testing will be complete by the end of 2010 but the one year period will allow for any delays. At the end of the testing, a final report will be completed for each brand/model/set point. This will include weather conditions during the test, measured rain simulator application intensity for all tests, average depth of rainfall before shut off, accuracy, average and standard deviation, depth of rainfall precision, average coefficient of variation, rainfall events not detected, and shut off in absence of rainfall.