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Ultrasonic Speed for Optimum Flow

Belimo’s larger sizes of inline flow sensors, from 2½ to 6 inches, offer automatic glycol measurement and compensation for optimal system performance. Since reliable flow measurement is essential in maximizing HVAC system efficiency and ensuring occupant comfort, these flow sensors utilize ultrasonic technology with glycol compensation to provide accurate and repeatable flow measurements of water and water/glycol mixtures without drift in any HVAC application.


The Belimo flow sensors use two offset transducers to determine the flow velocity by measuring the speed of sound in the heat transfer fluid. The downstream transit time is measured by passing an ultrasonic pulse from the lower transducer to the upper transducer; the process is then reversed to obtain the upstream time. Transit times differ based on the flow through the sensor tube; the downstream pulse is accelerated, while the upstream pulse is impeded and slowed. The ultrasound pulses with the fluid temperature and can be used to calculate the kinematic velocity and determine the measured volumetric flow.


From: Belimo; Danbury, Connecticut