Calibration of exhaust emission test devices

Preparation:

• Clean Equipment: Make sure the test equipment is clean and free of any contamination that might affect the results.
• Warm-Up: Allow the test devices to warm up to their operating temperatures as specified by the manufacturer.

Check Calibration Standards:

• Use certified calibration gases with known concentrations of the pollutants being measured (e.g., CO, CO?, NOx, HC). These gases should be traceable to national or international standards.

Perform Zero Calibration:

• Introduce a zero gas (usually nitrogen or air) to the system to ensure the device reads zero for all pollutants. Adjust the device if necessary to correct any drift.

Span Calibration:

• Introduce calibration gases with known concentrations of the target pollutants. Adjust the device settings to ensure it accurately reads the known concentrations. This process might involve adjusting the calibration coefficients or settings on the device.

Check for Linearity:

• Verify that the device can accurately measure across the entire range of expected pollutant concentrations. This involves testing at multiple concentrations to ensure the device responds proportionally.

Document Calibration:

• Record all calibration data, including the concentration of calibration gases, test conditions, and any adjustments made. This documentation is important for compliance with regulations and for troubleshooting any issues that arise later.

Perform Quality Control Checks:

• Regularly check the device with calibration gases to ensure ongoing accuracy. Implement a routine maintenance schedule to address any potential drift or performance issues.

Review and Verify:

• Cross-check calibration results with other instruments or standards if available, and verify that the device meets regulatory requirements and performance standards.

Recalibration Schedule:

• Follow a regular calibration schedule as recommended by the device manufacturer or regulatory authorities. This might involve daily, weekly, or monthly checks depending on the device and its usage.