Testing Landscape Irrigation Flow Sensors
Brent Q. Mecham
Flow sensors for landscape irrigation have long been used in conjunction with a separate flow controller, display, or compatible irrigation controller to monitor flow in residential and commercial landscape irrigation systems. Active flow monitoring conserves water, protects plant materials, and prevents site damage by detecting 1) Unscheduled flow events, 2) low flow events, and 3) high flow events caused by irrigation system component failures. Logic in the controller can then take corrective action to stop the water flow, sound an alarm or send alert messages. Flow sensors for irrigation systems were originally used to monitor flow within the irrigation system in real-time, however, they were not necessarily meant to measure water usage the same as a meter even though many of the flow sensors systems have the capability to totalize flow. This study and demonstration for testing irrigation flow sensors as proposed in the Smart Water Application Technologies (SWAT) draft testing protocol, focused on testing, modifying, and recommending improvements to a 2018 SWAT technology group release titled, Landscape Irrigation Flow Sensors, Equipment Functionality Test Protocol, Version 3.2. The intent of the testing standard is to validate how well the sensors perform in monitoring flow events compared to a master meter reading. The test equipment was located at the Irrigation Innovation Consortium Headquarters (Fort Collins, CO) and included two 275 gallon water tanks and provided positive suction to a 1 horsepower VFD pump station set to deliver up to 32 gpm at 70 psi to a PVC manifold holding multiple flow sensors from various manufacturers, which ultimately are downstream of two electromagnetic flow meters used as a flow standard for the experiment. Results of the experiment showed that the current protocol is effective but requires fine tuning; recommendations were made to the SWAT committee that test parameters for measuring how effective the flow sensors will monitor and manage flow should be included.