Liquid Vortex Flow Sensor also directly measures temperature.
Press Release Summary:

Designed for equipment manufacturers for system flow monitoring and control, DN Series operates on Karman's vortex trail principle, handles flow ranges from 0.24-39.6 gpm, and is accurate to 1% FS of measured value. Piezoelectric sensors embedded in ETFE vane located downstream of bluff detect generated vortices, and measured frequency represents flow velocity. This results in temperature-insensitive measurement of flow with minimal pressure loss.
Original Press Release:
New Liquid Vortex Flow Sensor Features High Accuracy and Low Cost
DN Series Liquid Vortex Flow Sensors also provide direct temperature measurement.
Hudson, MA-Clark Solutions announces the availability of a new family of liquid vortex flow sensors. DN Series Vortex Flow Sensors are designed specifically for equipment manufacturers as an excellent choice for system flow monitoring and control. Combining both high accuracy and low cost, DN Series Flow Sensors are accurate to 1% fs of measured value and are available for less than $100 in quantity.
Suitable for water & water glycol based heat exchange systems (with the usual additives) and other fluids, current DN Series models are suitable for flow ranges from 0.9 to 150 liters per minute (0.24 to 39.6 GPM).
DN Series Liquid Vortex Flow Sensors operate on the principle of Karman's vortex trail. Named after Theodore von Karman's mathematical description of the phenomenon, vortex-shedding flow meters present the flow in a pipe with an obstruction/bluff in the flow meter body. As velocity increases, alternating vortices are formed on each side of the bluff body and travel downstream. DN series flow sensors utilize piezoelectric sensors embedded in an ETFE vane located downstream of the bluff to detect the generated vortices. The frequency measured represents the flow velocity. The result is a temperature insensitive measurement of flow with minimal pressure loss. A flow factor is provided to convert frequency to volume flow rate for each model size. Versions with a 1000 Ohm RTD temperature sensor built-in to the bluff are available, providing direct temperature measurement in the medium.
Clark Solutions has a fifty-year history of providing unique solutions to the measurement, control, and monitoring of flow, pressure, and level in liquids and gases. Located in Hudson, Massachusetts, the company offers instrumentation devices to record, monitor, and control flow, velocity, pressure, temperature, humidity, level, gas concentration, and other properties. Clark Solutions also provides a wide range of pumps for liquids, gases, and air, including diaphragm pumps, piston pumps, rotary vane pumps, gear pumps, peristaltic pumps, impeller pumps, centrifugal pumps, and bellows pumps. Valve offerings include inert isolation valves, solenoid operated valves, valve actuators, pinch valves, manifold valves, ball valves, globe valves, butterfly valves, needle valves, and miniature and subminiature valves.
For more information, contact Donald Tyler, Sales Manager, Clark Solutions, 10 Brent Drive, Hudson, MA 01749, Tel. 978-568-3400, Fax 978-568-0060, email sales@clarksol.com, or visit our web site at www.clarksol.com. Web Page: www.clarksol.com/html/dn_series_inst.cfm
Prepared By: Frank Garrison, Garrison Bray Inc., 15 Longmeadow Road, Medfield, MA 02052, Tel: 508-359-1552, Fax: 877-348-9288