The ZJ-B7 Water Flow Sensor is a high-quality brass Hall-effect flow sensor designed to accurately measure the flow rate of clean water. As water passes through the sensor, an internal rotor generates pulse signals proportional to the flow rate, making it ideal for use with Arduino, ESP32, Raspberry Pi, PLCs, and other microcontroller-based systems. Its durable brass construction provides excellent pressure resistance and a longer service life than plastic flow sensors, making it suitable for water dispensers, coffee machines, irrigation systems, water purifiers, and industrial monitoring applications.

• Flow Rate Range: 1 to 25 Liters per minute (L/min)
• Thread/Interface Size: G1/2" (approx. 20mm outer diameter, standard 4-point interface)
• Operating Voltage: DC 5V to 15V (Minimum startup voltage: DC 4.5V)
• Output Signal Type: NPN Pulse square wave (approx. 50% duty cycle)
• Output Signal Amplitude: High level ≥ 4.7V (at DC 5V input); Low level ≤ 0.5V
• Flow Pulse Characteristic Formula: F = 11 × Q (± 3% to 5% accuracy), where F is the output frequency in Hz, and Q is the flow rate in L/min.
• Maximum Water Pressure: ≤ 1.75 MPa (approx. 253 PSI)
• Maximum Fluid Temperature: Up to 120°C (safe structural limits, though core electronics perform best under 80°C).

Electrical Pinout / Wire Connection

The device typically terminates into a 3-pin or 4-pin JST-SM connector:

• Red Wire: Power Supply Input (Positive, VCC)
• Black Wire: Power Ground (Negative, GND)
• Yellow Wire: Pulse Output Signal (Open-drain NPN pulse requiring a microcontroller pull-up resistor)

Usage & Installation Tips

• Flow Orientation: Pay attention to the unidirectional arrow stamped onto the brass casting; fluid must enter the tail side and exit pointing in the arrow direction for precise sensor wheel rotation.
• Debris Protection: Install a screen mesh filter prior to the sensor intake to keep stray rust particles or organic matter from clogging the internal impeller. 
• Magnetic Interference: Avoid mounting the sensor closely against high-power electrical transformers, heavy motors, or magnetic valves, which can disrupt the delicate Hall-effect sensor readouts.