1. Introduction
The LEFOO LFM751 is an advanced low differential pressure transmitter designed for precise measurement in environments containing air and neutral gases. This device features explosion-proof certification, ensuring safe and reliable operation in hazardous areas. Its robust cast aluminum shell provides guarding, while precision intelligent control contributes to a high safety factor and stable, reliable data.
This manual provides essential information for the safe and effective installation, operation, and maintenance of your LFM751 differential pressure transmitter.
2. Specifications
The LFM751 differential pressure transmitter offers reliable performance with the following technical specifications:
| Parameter | Value |
|---|---|
| Model Number | LFM751 |
| Type | Differential Pressure Transmitter |
| Pressure Range | -10000 ~ ±10000 Pa (Specific ranges: LFM751-6: -100~+100Pa; LFM751-0: -1000~+1000Pa; LFM751-2: -10000~+10000Pa) |
| Over-voltage | 10kPa (Range < 1000 Pa) / 80 kPa (Range > 1000 Pa) |
| Accuracy | ±0.5%FS (Range ≥500 Pa) / ±1%FS (Range <500 Pa) |
| Medium | Air and neutral gases |
| Operating Temperature | -20℃ ~ 70℃ |
| Compensation Temperature | -5℃ ~ 65℃ |
| Storage Temperature | -40℃ ~ 80℃ |
| Output Signal | 4~20 mA (two wire) |
| Load Resistance | ≤ 2500 Ω |
| Power Supply | 12~30 VDC |
| Explosion-proof Mark | Ex ia IIC T4 Ga / Ex ib IIIC T130°C Db |
| Explosion-proof Parameters | Ui: 30VDC; Ii: 120mA; Pi: 0.75W; Ci:0.01uF; Li: 0mH |
| Certification | CE certification, intrinsically safe explosion-proof certification, intrinsically safe dust explosion-proof certification, RoHS |
| Housing Material | Cast aluminum ADC12 (Note: The product shell is made of aluminum alloy. The risk of ignition caused by impact or friction must be prevented during use.) |
| Ingress Protection (IP) Rating | IP65 |
| Pressure Connector | Metal barbed interface, φ6.2mm |
| Cable Connector | Max cable diameter φ8mm |
| Weight | 375g |
3. Key Features
- Explosion-Proof Certification: Certified for safe use in hazardous environments with air and neutral gases.
- High Stability: Provides consistent and reliable data for critical applications.
- Anti-Electromagnetic Interference: Designed to resist electromagnetic interference, ensuring accurate readings.
- Multiple Protections: Incorporates various protective measures for enhanced durability and safety.
- Intelligent Control: Features precision intelligent control for optimal performance.
- Robust Construction: Housed in a cast aluminum ADC12 shell for durability and protection (Note: Prevent ignition risks from impact/friction).
- IP65 Protection Class: Offers excellent protection against dust and water ingress.
- Easy Installation: Designed for straightforward setup and integration.
4. Applications
The LEFOO LFM751 differential pressure transmitter is suitable for a wide range of industrial applications requiring precise pressure measurement in air and neutral gas environments, particularly where explosion-proof certification is necessary.
- Natural gas pipeline network monitoring
- Pharmaceutical plant clean engineering
- Power plant air supply systems
- HVAC systems in hazardous areas
- Industrial process control
5. Setup and Installation
Before installation, ensure the power supply is disconnected. Installation should be performed by qualified personnel in accordance with local electrical codes and safety regulations for hazardous environments.
5.1 Physical Dimensions
Refer to the diagram below for the physical dimensions of the LFM751 transmitter to ensure proper mounting space.
5.2 Mounting
- Select a suitable mounting location that is stable, free from excessive vibration, and within the specified operating temperature range.
- Ensure the location allows for easy access to pressure ports and electrical connections.
- Mount the transmitter securely using appropriate fasteners through the mounting holes. The device includes a grounding screw for safety.
5.3 Pressure Connections
- Connect the high and low pressure lines to the metal barbed interfaces (φ6.2mm) on the transmitter.
- Ensure all connections are tight and leak-free to prevent inaccurate readings.
- Verify that the medium (air or neutral gases) is compatible with the transmitter's specifications.
5.4 Electrical Wiring
The LFM751 uses a two-wire system for its 4-20 mA output signal and requires a 12-30 VDC power supply.
- Route the power and signal cables through the cable connector (max diameter φ8mm).
- Connect the power supply (12-30 VDC) and the 4-20 mA output signal to your control system according to the wiring diagram provided with your specific model variant (not provided in general documentation, refer to product-specific wiring instructions).
- Ensure proper polarity and secure all electrical connections.
- Connect the grounding screw to a reliable earth ground.
6. Operating Instructions
Once the LFM751 differential pressure transmitter is correctly installed and wired, it operates continuously to provide a 4-20 mA output signal proportional to the measured differential pressure.
- Power On: Apply the specified 12-30 VDC power supply to the transmitter.
- Monitoring Output: The transmitter will immediately begin measuring differential pressure and outputting a corresponding 4-20 mA signal. This signal can be read by a compatible control system, PLC, or display unit.
- Data Interpretation: The 4-20 mA output corresponds to the full pressure range of the specific LFM751 model (e.g., 4 mA for the minimum pressure, 20 mA for the maximum pressure). Refer to the specifications for your model's exact pressure range.
- Explosion-Proof Considerations: Always adhere to safety protocols for explosion-proof equipment. Do not open the device or perform any maintenance in a hazardous atmosphere unless specifically authorized and following strict procedures.
7. Maintenance
Regular maintenance ensures the longevity and accuracy of your LFM751 differential pressure transmitter.
7.1 Routine Checks
- Visual Inspection: Periodically inspect the transmitter for any signs of physical damage, corrosion, or loose connections.
- Pressure Connections: Check pressure lines and fittings for leaks or blockages. Ensure they are securely attached.
- Electrical Connections: Verify that all electrical wiring is secure and free from damage.
- Housing Integrity: Ensure the cast aluminum housing is intact and free from cracks or significant impact damage, especially in explosion-proof applications.
7.2 Cleaning
Clean the exterior of the transmitter with a soft, damp cloth. Do not use abrasive cleaners or solvents that could damage the housing or seals. Ensure the device is powered off before cleaning.
7.3 Calibration
While the LFM751 is designed for long-term stability, periodic calibration may be required depending on the application's accuracy requirements and regulatory standards. Consult a qualified technician for calibration procedures.
8. Troubleshooting
This section provides solutions to common issues you might encounter with the LFM751 transmitter. For complex problems, contact technical support.
| Problem | Possible Cause | Solution |
|---|---|---|
| No output signal (0 mA or constant 4 mA) |
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| Inaccurate or fluctuating readings |
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| Device not responding |
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9. User Tips
- For optimal performance, ensure the transmitter is installed in an environment that minimizes vibration and extreme temperature fluctuations.
- Always double-check pressure line connections for any potential leaks, as even small leaks can significantly affect differential pressure readings.
- When integrating with a control system, confirm the input range of your receiver matches the 4-20 mA output of the LFM751 for accurate scaling.
10. Warranty and Support
10.1 Warranty Information
The LEFOO LFM751 Differential Pressure Transmitter comes with a standard 1-year warranty from the date of purchase, covering defects in materials and workmanship under normal use. This warranty does not cover damage caused by improper installation, misuse, unauthorized modification, or external factors.
10.2 Technical Support
For technical assistance, troubleshooting, or warranty claims, please contact LEFOO customer service:
- WhatsApp: +86 13191616332
- Email: yierguoji01@163.com
Please have your product model (LFM751) and a detailed description of the issue ready when contacting support.
