The LEFOO LFM33 Differential Pressure Transmitter/Controller is a high-precision, multifunctional pressure sensor designed for measuring positive pressure, negative pressure, or pressure difference (differential pressure) in air or neutral gas get more info systems. With advanced MEMS sensing technology, multiple output and control options, and versatile installation modes, it delivers reliable performance across HVAC, clean room, ventilation, and air-filtration applications.
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???? Key Features & Advantages
High-precision MEMS digital pressure sensor
The LFM33 uses a MEMS-based sensor core for accurate detection of positive, negative, or differential pressure. This ensures sensitive pressure response and long-term stability.
Multifunctional: Display + Output + Control in one unit
It integrates an LCD digital display, analog/digital signal output, and relay control, offering flexibility and reducing the need for extra devices.
Flexible output and communication modes
Output options include 4–20 mA, 0–10 V analog signals, or RS-485 with Modbus RTU protocol, making LFM33 compatible with a wide range of control and data-logging systems.
On-site adjustable range & units
Internal output range can be adjusted, and pressure units are switchable — useful for global markets or mixed-system environments.
Built-in alarm & relay control
The device supports setting alarm thresholds, with an internal buzzer and LED alarm indicator upon abnormal pressure — enabling automatic control or alert in ventilation or clean-room systems.
Durable and safe build
Encased in flame-retardant ABS housing for good impact resistance and heat resistance; protection level rated IP65 — suitable for industrial or building-automation environments.
Technical Specifications
Parameter Specification
Measured Medium Air or neutral (non-corrosive) gases
Pressure Range (span) ±100 Pa, ±1000 Pa, ±10000 Pa
Accuracy ±1.0% Full Scale (F.S.)
Output Signals 4–20 mA, 0–10 V, or RS-485 (Modbus RTU)
Control Outputs 2 × SPDT relays (3A @ 250VAC / 30VDC) + optional buzzer alarm
Power Supply 16–30 VDC, ≤ 2.5 W power consumption
Protection Class IP65
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Housing Material Flame-retardant ABS (UL94-VO)
Installation Panel-mount with options for front, rear or side air intake
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Applications — Where LFM33 Excels
The LFM33 Differential Pressure Transmitter/Controller is ideal for many scenarios involving air or neutral-gas pressure monitoring and control:
HVAC systems — monitoring airflow, fan pressure, duct pressure, or maintaining balanced ventilation.
Clean rooms & laboratories — keeping stable pressure differential to control contamination, ensuring clean-room integrity.
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Air-filtration systems — monitoring filter resistance or pressure drop across filters for timely maintenance.
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Building automation & environmental control — integrating with BMS/SCADA via RS-485/Modbus for remote monitoring and control.
Why LFM33 Is a Smart Choice
Compact yet powerful — Combines measurement, display, control and communication, reducing complexity and installation footprint.
Highly adaptable — Modular outputs, adjustable measurement range, switchable units — meets diverse global application needs.
Reliable and stable — MEMS sensing core ensures accurate readings; ABS housing and IP65 rating add robustness for long-term industrial use.
Ready for automation — Support for Modbus RTU makes it ideal for modern HVAC/clean-room/BMS integrations.
Safety & alert-ready — Built-in alarm and relay control provide immediate response to abnormal pressure conditions.