Belimo has released new larger sizes of inline flow sensors, 2.5 inch to 6 inch, that offer automatic glycol measurement and compensation for optimal system performance. Belimo officials said the 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, the upstream pulse is impeded and slowed. The ultrasound pulses with the fluid temperature can be used to calculate the kinematic velocity () and determine the measured volumetric flow.

The flow sensors have a patented automatic glycol compensation algorithm that selects the correct fluid properties for the flow and energy calculation eliminating manual input of glycol percentage for sensor setup. The algorithm can be applied to a range of heat transfer fluids, ensuring accurate and repeatable measurements. The automatic glycol concentration minimizes drift and provides trusted flow measurement by continuously compensating glycol concentration in a hydronic system. 

Officials also said the sensors have no moving parts, require no calibration, and provide accurate, repeatable measurements improving the control and efficiency of HVAC systems. All flow sensors are wet calibrated to simulate field operation and are available with NIST traceable calibration certification. The 2.5-inch to 6-inch flow sensors now completes the FM series flow sensor offering. The new sizes will be available in August.