Black Water Flow Sensor (Sea) YF-S201B Flowmeter G1/2 1-30L/min 5V

The YF-S201B Water Flow Sensor is a widely used and trusted inline flow measurement device for projects involving water and other low-viscosity liquids. It features a black plastic valve body with standard G1/2" male threaded connections on both ends, allowing quick and leak-free integration into existing pipe systems and DIY water lines.

Inside the sensor, a plastic rotor (paddle wheel) rotates as water flows through the valve. A high-quality Hall-effect sensor mounted alongside the rotor detects the rotation magnetically and outputs a digital pulse signal, where the frequency of the pulses is directly proportional to the flow rate. By counting these pulses over a specific time interval using a microcontroller, users can accurately calculate flow rate (L/min) and total water volume (L).

The sensor operates over a wide voltage range of DC 5V to 24V, making it compatible with 5V Arduino, 3.3V ESP32 (with level shifting), 12V industrial circuits, and 24V automation systems. With its low current consumption (15 mA at 5V), it can be powered easily by most embedded systems without adding stress to the power supply.

The body is engineered with high sealing performance to prevent leaks and is designed to handle water pressures up to 1.75 MPa (~17.5 bar). The sensor can measure liquid temperatures up to 120°C and operates safely in environments up to 80°C, allowing use in both cold and hot water systems, including coffee machines, water dispensers, and small heating loops. The sensor is RoHS compliant, ensuring safe and environmentally responsible operation.

The YF-S201B is a great upgrade from the standard YF-S201, offering improved housing durability, better sealing, and a more refined output signal, making it a top choice for both hobbyist and semi-industrial flow monitoring applications.

Specifications

• Model: YF-S201B (Sea)
• Color: Black
• Connection Size: G1/2" Male Thread (both ends)
• Sensor Type: Hall-Effect
• Output Signal: Digital pulse (proportional to flow rate)
• Flow Rate Range: 1 – 30 L/min
• Working Voltage: DC 5V – 24V
• Minimum Working Voltage: DC 4.5V
• Maximum Working Current: 15 mA (at 5V)
• Load Capacity: ≤ 10 mA (at 5V)
• Maximum Water Pressure: ≤ 1.75 MPa
• Operating Temperature: ≤ 80°C
• Liquid Temperature: ≤ 120°C
• Operating Humidity: 35% – 90% RH
• Storage Temperature: -25°C to +80°C
• Storage Humidity: 25% – 95% RH
• Compliance: RoHS Compliant

Note: Always observe the flow direction arrow marked on the sensor body. Use Teflon tape (PTFE) on the threads to ensure a leak-free seal when installing into pipes. The pulse frequency can be converted to flow rate in your code using a calibration factor, typically around F = 7.5 × Q (L/min) for the standard YF-S201 family — small calibration may be required for best accuracy in specific systems.

Applications

• Smart Water Dispensers and Coffee Machines for measuring dispensed liquid
• DIY Water Meters and Flow Monitoring Devices
• Smart Irrigation Systems for gardens, greenhouses, and farms
• Aquariums and Hydroponics flow control and circulation monitoring
• Boiler and Heating Systems for monitoring hot water flow
• Reverse Osmosis (RO) and Water Filtration Systems
• Solar Water Heaters for circulation pump control
• Industrial Process Monitoring in light-duty fluid systems
• IoT-Based Smart Home Water Monitoring with ESP32, ESP8266, or Raspberry Pi
• Leak Detection and Water Usage Logging
• Educational STEM Projects demonstrating flow measurement principles
• Arduino-Based Automation Projects for fluid control