Flow sensor PFLOW-ELEMENT

humiditymedical

Measuring range [SCCM] Customized Accuracy [± % FS] max. Customized Humidity range 0...100% RH, resistant to water condensation Supplier Pewatron Output signal Customized Supply voltage [VDC] Customized Wetted materials Silicon carbide, epoxy, PPS, FR4, silicone as static seal Product description Flow Sensor element based on thermal principle customized package available FEATURES MEMS Thermopiles & Heater Excellent wetted parts compatibility No offset and Drift Pressure Resistant, >15 bar Simple Signal Conditioning APPLICATIONS Medical respirators and ventilators HVAC Process Control DESCRIPTION The SFD flow sensing die consists of two thermopiles symmetrically positioned upstream and downstream from a heater element which heats up the hot junctions. The thermopile generates an output voltage proportional to the temperature gradient between its hot and cold junctions (the Seebeck effect). The hot junctions of the thermopiles and the heater reside on a thermal isolation base. In case the medium is static, the temperature profile upstream and downstream from the heater is symmetric; In case the medium flows, the temperature profile skews in the flow direction due to heat transport of the flowing medium, causing changes in thermopile output. Heat transport is proportional to mass flow and heat capacity of the medium. Therefore the sensor measures the mass flow of the medium A reference resistor is placed next to the cold junction of the upstream thermopile to provide input for temperature compensation.