流量传感器：计算体积流量和质量流量

　　流量传感器：计算体积流量和质量流量

　　流量传感器用来测量液体、气体的流速、体积流量或质量流量。气体质量流量在标准升每分钟单位指定（SLM）或每分钟标准立方厘米（SCCM）。通过将体积流量参考标准温度和压力，可以从体积流量中计算出精确的质量流量（G／min）。图1显示了气体/液体流量开关和控制的一些例子。

　　To design with and properly use gas/liquid sensors， we must first take some preliminary steps and also understand some terms and equations in order to get our desired design results. First， let’s look at any external support circuitry that may be needed for the sensor. Airflow sensors without an internal sensor amplifier and other circuitry sometimes require external heater control circuitry （Fig. 2）， power to bias an internal sensing bridge （Fig. 3）， and amplification and conditioning of the sensor output signal （Fig. 4）。 STMicroelectronics LM2902 op amps may be used to construct this circuit.