The City of Fontana, California (pop. 200,000) has many landscaped traffic islands and median strips. The city has suffered severe droughts in recent times, and the conservation of water and the maintenance of valuable trees and shrubs in public spaces has been a major concern. The annual water usage budget for the city is $250,000.
Many of the city's green areas on traffic islands use drip irrigation to water the plants and shrubs. City officials were monitoring the water usage via paddle wheel flow sensors attached to a remote alarm system. The paddle wheel flow sensors were ineffective because they were continually giving false positives—showing "no flow" when the flow was below the threshold of the sensor to actually sense.
Paddle wheel sensors have an impeller that requires enough flow velocity to overcome the friction of the wheel on the shaft to sense any flow. In low flow situations, like drip irrigation, paddle wheel sensors often cannot register low flow readings.
The ultrasonic QS200 flowmeter has no moving parts and requires much lower flow rates to register a reading. It "retrofits" into most leading irrigation systems.
The City installed the FLOMEC QS200 in a single installation with bubbler head for drip irrigation with flow below 3 GPM, retrofitting it in the existing housing. The low flow alarms were reset for the QS200 ultrasonic flow meters.
A low flow alarm from the QS200 occurred and was thought to be another false alarm, which had occurred previously with the paddle wheel sensors. When the alarm was investigated, however, it was found that there was a blockage in the nozzle and no water was reaching the meter or plants.
The ability of the meter to detect low flows, typical of bubbler head nozzles and drip line water velocities, saved the city the cost of replacing the greenery for the entire median strip—an expensive and difficult job when complicated with traffic flow. Savings were estimated by the City of Fontana Engineer in the thousands of dollars.