The core of sensor calibration is “Preparation, Calibration, and Verification”. The key steps must strictly follow the following process:
1. Preparation before Calibration – Confirm Calibration Environment: Maintain stable environmental parameters such as temperature, humidity, and atmospheric pressure (e.g., temperature controlled at 23±2°C), avoiding vibration and electromagnetic interference.
– Check Equipment Status: Ensure the sensor is undamaged, and that the connection cables and interfaces are normal; the standard instruments for calibration (such as standard resistors and signal generators) must be within their validity period and have an accuracy at least three times higher than that of the sensor being calibrated.
– Preheat and Stabilize: Preheat the sensor and standard instruments as per the manual requirements (e.g., preheat for 30 minutes) to ensure the equipment reaches a stable operating state.
2. Calibration Execution – Connect Devices: Correctly connect the sensor and standard instruments according to the calibration plan, ensuring accurate signal transmission (e.g., voltage signals connected to the corresponding range channel).
– Apply Standard Signals: Sequentially apply at least five standard points (including zero and full scale) from the lower limit to the upper limit of the range, recording the sensor’s output value after each point stabilizes.
– Reverse Calibration Verification: Repeat the application of standard signals from the upper limit to the lower limit, recording the output values again to avoid the influence of sensor hysteresis errors on the results.
3. Data Processing and Verification – Calculate Errors: Compare the “Standard Value” of each standard point with the “Sensor Output Value”, calculating indicators such as display error, repeatability, and linearity, which must meet the sensor’s accuracy requirements (e.g., error ≤ ±0.5% FS). – Calibration Records: Fully document the calibration date, environmental parameters, standard instrument information, data for each point, and error results to form a calibration report.
4. Post-Calibration Confirmation – Restore Installation: Install the sensor back to its original position and connection method, ensuring it is securely fixed and wired correctly.
– On-Site Verification: Apply typical signals from actual work conditions to confirm the sensor output is normal and consistent with the calibration results.
– Cycle Planning: Based on the sensor’s usage frequency and accuracy requirements, set the next calibration cycle (e.g., 3 months, 6 months).
