1. Profile

The MH-Z14A NDIR Infrared gas module is a common, small-size sensor utilizing the non-dispersive infrared (NDIR) principle to detect the existence of CO2 in the air. It offers good selectivity, is non-oxygen dependent, and has a long lifespan. It features built-in temperature compensation and provides digital output (UART), analog voltage output, and PWM output. This sensor is developed through the integration of mature infrared absorbing gas detection technology, precision optical circuit design, and superior circuit design.

Diagram Description: The diagram shows a top view of the MH-Z14A module with various pins and components labeled. It includes dimensions and pin assignments.

2. Applications

• HVAC refrigeration equipment
• Air quality monitoring equipment
• Fresh air systems
• Air purification equipment
• Smart home systems
• Schools

3. Main functions and features:

• Gold-plated chamber, waterproof & anti-corrosion treatment
• High sensitivity, Low power consumption
• Good stability
• Temperature compensation, excellent linear output
• Output modes: UART, analog voltage signal, PWM wave
• Long lifespan
• Anti-water vapor interference
• No poisoning

4. Main technical parameters

Accuracy Table:

5. Structure

Diagram Description: The diagram displays the physical structure of the MH-Z14A module with detailed dimensions in millimeters. It shows the top, side, and bottom views, highlighting the sensor's layout and key features.

6. Definition for pins

Diagram Description: This diagram illustrates the pinout of the MH-Z14A module, showing the arrangement of pins on the connector and their corresponding functions.

7. Automatic Baseline Correction (ABC function)

The ABC function allows the sensor to perform zero point judgment and automatic calibration intelligently after a continuous operation period. The automatic calibration cycle occurs every 24 hours after power-on, with a zero point set at 400ppm. As of July 2015, the default setting includes the built-in automatic calibration function. For optimal sensor performance, it should be placed in clean air for over 1 hour.

The ABC function is suitable for office and home environments. However, it is not recommended for environments like greenhouses, farms, or refrigerators where automatic calibration may be undesirable. In such cases, the automatic calibration function should be disabled, and users should perform zero detection and calibration regularly, either by command or manually.

8. Notes

• 8.1 Please avoid applying pressure to the gilded plastic chamber from any direction during welding, installation, and use.
• 8.2 When placing the sensor in a small space, ensure the area is well-ventilated, especially for diffusion through windows.
• 8.3 The sensor should be kept away from heat sources and direct sunlight or other heat radiation.
• 8.4 Avoid using the sensor in high-dust environments for extended periods.
• 8.5 To ensure normal operation, the power supply must be within the 4.5V~5.5V DC range, and the power current must be not less than 150mA. Deviations from this range may lead to sensor failure (e.g., low concentration output or inability to function).
• 8.6 During manual zero point calibration, the sensor must operate in a stable gas environment (400ppm) for over 20 minutes. Connect the HD pin to a low level (0V) for over 7 seconds.