Description
The MQ-D4 (MQ-D4B) is a semiconductor-type combustible gas sensor designed for methane (CH4), natural gas, and LPG detection in domestic and industrial gas leakage alarms. Its sensing element uses tin dioxide (SnO₂) deposited on a micro Al₂O₃ ceramic substrate, with an integrated heater that maintains the sensing material at the optimal operating temperature . In clean air, the sensor exhibits low conductivity. When combustible gases are present, the conductivity increases proportionally to gas concentration, allowing a simple circuit to convert this change into an output signal .
The sensor is highly sensitive to methane and also responds to propane and butane, making it suitable for natural gas leak detection. It features low power consumption, fast response and recovery, good stability, and a long service life . Typical applications include domestic gas leak detectors, industrial gas monitors, and portable gas detection instruments .
Critical limitation: The MQ-D4 is not a calibrated, quantitative measurement device. Like all MQ-series sensors, it responds to multiple gases, drifts over time, and requires calibration against a known gas mixture for meaningful concentration readings. It is best suited for relative leak detection and alarm triggering, not precise ppm measurement .
Features
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High Methane Sensitivity: Optimized for CH4 and natural gas detection, with good response to LPG components (propane, butane) .
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Semiconductor (SnO₂) Sensing Element: Low conductivity in clean air; conductivity increases with combustible gas concentration .
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Fast Response and Recovery: Response time ≤30s, recovery time ≤60s .
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Low Power Consumption: Heater power ≤350mW, heating voltage 5.0V ±0.1V .
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Simple Drive Circuit: Requires only heater voltage (VH) and circuit voltage (VC) with a load resistor .
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Long Service Life: Manufacturer-rated at approximately 10 years .
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Compact Metal Package: Standard metal housing for easy integration .
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Module Versions Available: MQ-4 breakout modules add LM393 comparator, potentiometer, and dual AO/DO outputs for direct microcontroller use .
Technical Specifications
| Parameter | Specification (Bare MQ-D4B Sensor) |
|---|---|
| Target Gases | Methane, Natural Gas, LPG, Propane, Butane |
| Detection Range | 300–10,000 ppm (Methane/Natural Gas) |
| Heating Voltage (VH) | 5.0V ± 0.1V AC or DC |
| Circuit Voltage (VC) | ≤24V DC |
| Heater Power | ≤350mW |
| Sensitivity | Rs(air)/Rs(5000ppm CH4) ≥ 5 |
| Response/Recovery Time | ≤30s / ≤60s |
| Preheat Time | ≥48 hours |
| Operating Temperature | -10°C to +50°C |
| Humidity Range | <95% RH |
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