Preparation before Verification: Prepare a Class II standard thermocouple that has undergone metrological certification, a low-potential DC potentiometer with an accuracy of 0.02, and a high-precision digital thermometer. Confirm that all standard equipment is within its metrological validity period and has an accuracy greater than one-third of the allowed error of the thermocouple being evaluated.
Full-Temperature Range Standard Comparison Verified: Secure the hot junctions of the standard thermocouple and the Husky thermocouple to be calibrated, and insert them into the appropriate temperature detecting holes in the hot runner. Ensure that both sensor junctions are in the same temperature field and in full contact with the runner wall.
Choose three common hot runner temperature points: 20%, 50%, and 80% of the thermocouple's range. Gradually increase the temperature from low to high while keeping a consistent temperature at each position for 30 minutes. The temperature field change should be ≤0.2℃/min.
Cycle through the temperature data in a "standard-calibrated-standard" sequence, collecting at least four measurements at each temperature point. Record the conventional thermocouple's measured temperature and the Husky temperature controller's reported temperature, then calculate the indication error for each point.
The indication deviation at all test sites across the full temperature range shall be ≤ ±1℃, according to the permitted error range of the applicable national standard for the graduation number. This means that the static temperature measurement accuracy fulfils the criteria.
System Stability Verification: Heat the system to the standard production temperature and run it at that temperature for 2 hours. Examine the temperature curve on the temperature controller. If the temperature fluctuation is ≤ ±1℃ and there are no leaps or unidirectional drift, the system temperature measurement meets the criteria.
Verify the accuracy of cold junction correction by placing the module at three common room temperature points (20℃, 25℃, and 30℃). Consider the difference between the temperature displayed by the temperature controller and the standard temperature. If the cold junction compensation error is less than ±0.1℃, the component's accuracy meets the criterion.
The Heating-Deceleration Hysteresis Test involves taking two measurements at the same temperature point, one for heating and one for cooling. A variation of ≤±0.5℃ between two observations suggests the thermal hysteresis error is acceptable.
Verify auxiliary performance by retesting insulation resistance between thermocouple electrodes and exterior casing. The insulation resistance is proven to be ≥100MΩ, with no signal divergence due to leakage.
Dynamic Response Test: The thermocouple is rapidly heated to the desired temperature. The temperature display takes ≤15 seconds to reach 90% of its steady-state value, suggesting good dynamic response and no hysteresis-related temperature measurement variation.
This verification technique fully complies with industrial metrological calibration standards and can 100% certify that the calibrated Husky thermocouple's accuracy is compliant and satisfies the criteria.
