Micro Inline Water Flow Sensor - Hall Effect 3.3V-5V for 4-5mm Tubing

Specifications

• Operating Voltage: 3.3V to 5V DC

• Output Type: Digital Square Wave (Pulse)

• Sensor Type: Hall Effect

• Hose Compatibility: Fits 4mm to 5mm Inner Diameter (ID) tubing

• Nozzle Outer Diameter: ~5.8mm to 6.3mm (Barbed)

• Total Length: 35mm

• Wiring Pinout: Red (+VCC), Black (GND), Yellow (Signal Output)

Key Applications and Projects

• Automated Plant Care: Splice this into the tubing of a mini 5V submersible pump to ensure your Arduino delivers exactly 100mL of water to your bonsai tree every morning, rather than just guessing based on a timer.

• PC Water Cooling: Adding a visual and digital safeguard to your custom computer cooling loop. If the sensor stops sending pulses, your motherboard knows the pump failed and can safely shut down the PC before it overheats.

• Smart Coffee Makers: Accurately measure the amount of water pulled from the reservoir to brew the perfect cup of espresso.

Unlock New Capabilities (Project Evolution)

• The Robotic Bartender: Don't just pump water; mix drinks! Evolve your project by building an automated cocktail machine. Hook up three mini peristaltic pumps to three different bottles (juice, soda, syrup), and place one of these inline sensors on each tube. Using an ESP32 and an OLED screen, you can program exact recipes. The pumps will turn on, the sensors will count exactly 2 ounces of juice and 1 ounce of syrup, and the pumps will instantly shut off, mixing a perfect, repeatable drink every single time!

Virtual Technician & Wiring

⚠️ Safety Warning: Do not use this sensor on metallic pipes; it relies on capacitance changes which are shielded by metal.

• Red Wire: VCC (3.3-5V)

• Black Wire: GND 

• Yellow Wire: Signal

Accessories

• 1 x Micro Inline Water Flow Sensor (with pre-attached 3-wire cable and connector)

Frequently Asked Questions (FAQ)

1. What size tubing is this sensor compatible with? The barbed nozzles are designed for a tight friction-fit with flexible silicone or PVC tubing that has an Inner Diameter (ID) of 4mm to 5mm.

2. What is the operating voltage for this sensor? The built-in Hall effect sensor is rated to operate on 3.3V to 5V DC.

3. How do I wire this sensor to my microcontroller? Connect the Red wire to your power supply (3.3V or 5V), the Black wire to Ground (GND), and the Yellow wire to a Digital Input pin.

4. What kind of output signal does the yellow wire provide? It outputs a digital square wave (pulse signal). The pin goes HIGH and LOW rapidly as the internal turbine spins.

5. Can I run 12V or 24V through this sensor? No. Supplying voltages higher than 5V will permanently destroy the Hall effect chip on the circuit board.

6. Does this sensor output an analog voltage based on water pressure? No. It only outputs digital pulses based on the rotation speed of the turbine. It measures flow rate, not static line pressure.

7. How do I calculate the flow rate using Arduino? You must use a "Hardware Interrupt" in your code to count the number of pulses on the yellow wire over a set time (e.g., 1 second). You then multiply that count by a calibration factor to determine Liters per Minute (L/min).

8. Is this sensor food-safe or suitable for drinking water? While the plastic housing is generally inert, this is a generic DIY electronic component and is not officially FDA-certified or graded for commercial food/medical use. Use with consumables at your own discretion.

9. Can it measure boiling water? No. Passing boiling water (100°C) through the sensor can warp the plastic housing, melt the internal seals, or thermally damage the Hall effect sensor. Stick to cold or warm liquids.

10. Does the water have to flow in a specific direction? Yes. Turbine sensors operate best in one specific direction. If there isn't an arrow printed on the housing, test it by blowing air through it; the direction that makes the turbine spin faster and smoother is the correct flow path.

11. Do I need to use hose clamps on the tubing? If you are using 4mm ID silicone tubing, the fit is usually tight enough for low-pressure gravity feeds. If using 5mm tubing or an active pump, using tiny zip-ties or micro hose clamps over the barbs is highly recommended to prevent pop-offs.

12. Can I use this directly with a Raspberry Pi? Yes! Because it operates perfectly on 3.3V, you can connect the signal wire directly to a Raspberry Pi's 3.3V GPIO pins without needing a logic level converter.

13. Do I need a pull-up resistor for the yellow signal wire? Most microcontrollers allow you to use an internal pull-up resistor via code (e.g., pinMode(pin, INPUT_PULLUP) on Arduino). If your readings remain erratic, adding a physical 10k Ohm resistor between the Yellow wire and the Red wire will stabilize the signal.

14. What are the physical dimensions of the sensor? The total length from tip to tip is 35mm, and the barbed nozzles have an outer diameter of roughly 5.8mm to 6.3mm.

15. Why is my sensor leaking from the middle seam? The two halves of the clear plastic housing are sealed together for low-pressure applications. If you subject the sensor to extreme water pressure from a high-power pump, you can blow the internal seal.

16. Can this sensor measure extremely slow drips? No. Turbine sensors require a minimum flow rate to overcome the physical friction of the rotor. It will not accurately register very slow, individual drips of water.

17. Can it measure thick, viscous liquids like oil or honey? No. Thick or sticky liquids will jam the tiny turbine inside the housing. It is designed specifically for water and similar low-viscosity fluids.

18. Is the entire sensor waterproof? Can I submerge it? No. While the inside of the tube where the water flows is sealed, the external green circuit board, the Hall effect chip, and the wire connections are completely exposed. Do not submerge the sensor in water.

19. What type of connector is on the end of the wire? The pre-attached 3-wire cable typically terminates in a standard female JST-style connector (often 2.54mm pitch), making it easy to plug into sensor shields or use with jumper wires.

20. Can I use this sensor to detect if a pump has run dry? Yes! This is a very common use case (especially in PC water cooling). If your pump is turned on but your microcontroller is reading 0 pulses from the sensor, you can program the system to trigger an alarm or shut down to prevent the pump from burning out.