YF-B9 Water Flow Sensor (¾" BSP, 2–50 L/min)
YF-B9 Water Flow Sensor (¾" BSP, 2–50 L/min)
11 in stock
💧 YF-B9 Water Flow Sensor — ¾" BSP, 2–50 L/min (Hall Effect, DC 5V)
A ¾-inch (G3/4) hall-effect water flow sensor for measuring flow rates from 2 to 50 litres per minute. Outputs a pulse signal proportional to flow rate — connect to an ESP8266, ESP32, Arduino, or Raspberry Pi to build a smart water meter for household branch lines, garden taps, or individual appliance monitoring. DC 5V powered, 3-wire interface (VCC, GND, Signal). The most common pipe size for SA household plumbing.
Choose your flow sensor:
⚡ Key Features
- ¾" BSP Thread (G3/4) — the most common pipe fitting in SA household plumbing; fits directly onto garden taps, geyser inlets, washing machine valves, and branch lines
- 2–50 L/min Flow Range — covers the typical flow of a single tap (~8–12 L/min) up to a full garden hose or multiple simultaneous outlets
- Hall Effect Pulse Output — each pulse corresponds to a calibrated volume; count pulses to calculate L/min and total litres consumed
- DC 5V Operation — 3-wire connection: Red (5V VCC), Black (GND), Yellow (Signal output)
-
ESPHome / Home Assistant — use the built-in
pulse_countersensor in ESPHome for instant integration into your Home Assistant water monitoring dashboard - Compact & Inline — small enough to fit in tight spaces under sinks, in geyser cupboards, or inside irrigation valve boxes
- Brass Fittings — more durable threads than plastic; better seal with standard plumber's tape (PTFE)
🏠 Perfect For
Household Water Monitoring
Install on the main branch line or individual outlets to track daily water usage. Get alerts in Home Assistant when usage exceeds your daily target — essential for SA water-conscious homes.
Geyser Inlet Monitoring
Mount on the cold water inlet to your geyser. Track hot water consumption and detect if the geyser's pressure relief valve is leaking by monitoring unexpected flow when no taps are open.
Garden Irrigation Zones
Measure exactly how many litres each irrigation zone receives per cycle. Combine with a smart valve for volume-based shutoff instead of time-based — more accurate and water-efficient.
Leak Detection
If the flow sensor reports water flow when all taps are closed, you have a leak. Automate alerts in Home Assistant to catch leaks early before they cause damage or inflate your water bill.
📋 Technical Specifications
| Product | YF-B9 Water Flow Sensor |
| Model | YF-B9 |
| Thread Size | ¾" BSP (G3/4) |
| Flow Range | 2–50 L/min |
| Working Voltage | DC 5V |
| Output | Hall effect pulse (square wave) |
| Wiring | Red (5V) · Black (GND) · Yellow (Signal) |
| Fitting Material | Brass |
| Body Material | Nylon / engineering plastic |
| Suitable For | Cold water only |
| Compatible With | ESP8266 · ESP32 · Arduino · Raspberry Pi · ESPHome · Home Assistant |
🔗 Pair With
D1 Mini
Flash ESPHome, wire the signal to GPIO4. Smart water meter reporting to Home Assistant in minutes.
View Product →SONOFF Smart Water Valve
Pair flow monitoring with automatic shutoff. Detect a leak via the flow sensor → close the valve via Home Assistant.
View Product →❓ Frequently Asked Questions
Which size do I need — ¾" or 1½"?
Can I use it with hot water?
How do I connect it to Home Assistant?
pulse_counter sensor platform, set the GPIO pin, and add a calibration lambda to convert pulses to litres. The sensor appears in Home Assistant automatically with flow rate (L/min) and total consumption (litres).🤝 Need Help? We're Here for You!
Visit Us
8 Wildebraam Street
Weltevreden Park, Roodepoort
Gauteng, 1709
Track Every Litre 💧
DIY smart water metering for SA homes — the right size for household plumbing.
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