Saier HZ21FW Water Flow Sensor (1–30 L/min) - Turbine Sensor, DC 4.5-18V

The HZ21FW sensor provides flexible output options. It can generate a digital pulse signal where the frequency corresponds to the flow rate, suitable for direct microcontroller input. It also offers an analog voltage output, proportional to the flow rate, for interfacing with analog-to-digital converters (ADCs) or PLC analog input modules.

The sensor operates on a wide DC voltage range of 4.5 to 18 volts. Typical wiring involves connecting the red wire to your positive DC supply (VCC), the black wire to ground (GND), and the yellow (or signal) wire to your controller's digital input pin for pulse counting or analog input pin for voltage reading. Always ensure your power source can supply the required ≤15mA current.

While primarily designed for water and compatible liquids, the HZ21FW's turbine mechanism can also measure the flow of compatible, clean, and dry gases. However, accuracy specifications are validated for liquids. For gas applications, specific calibration may be required, and the user must ensure the gas does not damage the internal components.

For the digital pulse output, you measure the frequency (pulses per second). The sensor's datasheet or calibration sheet provides a K-factor (pulses per liter). Flow rate (L/min) = (Frequency * 60) / K-factor. For the analog output, map the measured voltage (between the specified low and high output levels) linearly across the 1-30 L/min range using your controller's ADC.