1. Introduction
The DIGITEN FL-408NPT is a G1/2" NPT Hall effect water flow sensor designed for accurate measurement of liquid flow rates. This sensor provides a pulse output signal proportional to the flow, making it suitable for various applications requiring precise flow monitoring. This manual provides essential information for the proper installation, operation, and maintenance of your FL-408NPT water flow sensor.
2. Product Overview
The FL-408NPT water flow sensor features a compact and lightweight design, ensuring ease of installation. It incorporates a magnetic Hall effect sensor sealed from the water path, which generates an electrical pulse with each rotation of the internal rotor. The sensor is constructed with materials that comply with ROHS standards and are food-grade, ensuring safety and durability. It is designed to be water-proof, leak-proof, pressure-resistant, heat-resistant, and cold-resistant.
Image 1: DIGITEN FL-408NPT Water Flow Sensor. This image shows the compact design of the sensor with its G1/2" NPT threaded connections and three-wire cable for electrical connection.
Key applications include water heaters, drinking water machines, coffee makers, water flow control systems, waterworks, farmland and garden irrigation, and water purification systems.
3. Specifications
| Parameter | Value |
|---|---|
| External Connect Thread Diameter | G1/2 inch (NPT) |
| Withstand Water Pressure | 1.75 Mpa below |
| Output Waveform | Square Wave, pulse signal |
| Pulse Frequency Formula | F = 7.5 * Q (L / Min) |
| Working Voltage Range | DC 3-24 V |
| Maximum Current | 15 mA (DC 5V) |
| Load Capacity | ≤10 mA (DC 5V) |
| Flow Range | 1-30 L/min |
| Insulation Resistance | >100M OHM |
| Storage Temperature | -25℃ to +80℃ |
| Storage Humidity | 25% to 95% RH |
| Operating Humidity | 35% to 90% RH |
| Operating Temperature | ≤80℃ |
| Cable Length | 15 cm |
| Tolerance | ±2% |
| Material | Copper |
| Item Weight | 0.05 Kilograms |
4. Setup
4.1 Installation
- Ensure the water supply is turned off before installation.
- Identify the correct flow direction. The sensor typically has an arrow indicating the direction of water flow.
- Connect the G1/2" NPT threads of the sensor to your plumbing system. Use appropriate thread sealant (e.g., PTFE tape) to ensure a leak-proof connection. Do not overtighten.
- Mount the sensor securely in a stable position. While the mounting type is listed as 'Wall Mount', ensure it is installed in a manner that prevents vibration and stress on the connections.
4.2 Electrical Connection
The FL-408NPT sensor uses a three-wire connection. Connect the wires as follows:
- Red Wire: Connect to the positive (+) terminal of your DC power supply (3-24 V).
- Black Wire: Connect to the negative (-) terminal of your DC power supply (Ground).
- Yellow Wire: This is the pulse signal output. Connect it to the input of your microcontroller or data acquisition system.
Ensure all electrical connections are secure and insulated to prevent short circuits or damage.
5. Operating Instructions
5.1 Powering On
Once the sensor is physically installed and electrically connected, apply power within the specified working voltage range (DC 3-24 V).
5.2 Flow Measurement
When water flows through the sensor, the internal rotor spins, and the Hall effect sensor generates a series of electrical pulses. The frequency of these pulses is directly proportional to the water flow rate.
5.3 Interpreting the Output Signal
The pulse frequency (F) in Hz can be converted to flow rate (Q) in Liters per Minute (L/min) using the formula:
F = 7.5 * Q
Therefore, to find the flow rate:
Q (L/min) = F / 7.5
Your microcontroller or data acquisition system should be programmed to count the pulses over a specific time interval to determine the frequency and subsequently calculate the flow rate.
6. Maintenance
- Regular Inspection: Periodically check the sensor and connections for any signs of leaks, corrosion, or damage.
- Cleaning: If the sensor's accuracy degrades over time, it may be due to debris accumulation. Disconnect the sensor from the water supply and electrical connections, then carefully flush it with clean water. Avoid using harsh chemicals or abrasive materials.
- Environmental Conditions: Ensure the sensor operates within its specified temperature and humidity ranges to prolong its lifespan.
- Storage: If storing the sensor, ensure it is clean, dry, and kept within the recommended storage temperature and humidity.
7. Troubleshooting
- No Pulse Output:
- Check power supply connections (Red to +, Black to -) and ensure voltage is within DC 3-24V.
- Verify water flow through the sensor.
- Inspect the yellow signal wire connection to your reading device.
- Inaccurate Readings:
- Ensure the sensor is installed correctly with the proper flow direction.
- Check for air bubbles or debris in the water line that might affect the rotor's movement.
- Verify the pulse counting logic in your software.
- Confirm the power supply is stable and within the specified range.
- Leaks:
- Turn off water supply immediately.
- Check thread connections for proper sealing and tightness. Reapply thread sealant if necessary.
8. Warranty and Support
For warranty information and technical support, please refer to the product packaging or contact DIGITEN customer service through their official channels. Keep your purchase receipt for warranty claims.
