Operation process: Place the transmitter and standard platinum resistance thermometer in a constant temperature bath, simulate the temperature signal through a resistance box or millivolt signal generator, adjust the zero point (4mA) and full degree (20mA) potentiometers to make the output current consistent with the standard value.

Advantages: Stable environmental temperature field, minimal interference factors, suitable for high-precision measurement and type evaluation, high repeatability of calibration results.

Limitations: The equipment needs to be disassembled and transported to the laboratory, which takes a long time and cannot reflect the actual working conditions on site (such as vibration and electromagnetic interference).

On site calibration: a fast and flexible adaptive solution

On site calibration is designed for actual working conditions, emphasizing operational convenience and environmental adaptability.

Equipment configuration: Portable constant temperature bath, dry well furnace, and handheld calibrator are used. The temperature range is usually -20 ℃ to 300 ℃, with uniformity ≤ 0.3 ℃ and fluctuation ≤ 0.05 ℃/15min.

Operation process: Calibrate directly at the installation location of the equipment, adjust the output by simulating temperature signals, and observe the impact of actual operating conditions on the measurement results (such as pipeline temperature hysteresis).

Advantages: No need to disassemble equipment, saving time and cost, and can promptly detect and correct on-site errors (such as loose wiring and sensor aging).

Limitations: Environmental disturbances such as temperature fluctuations and vibrations may affect calibration results, and accuracy needs to be improved by taking the average of multiple measurements.

Comparative summary: Choose as needed, balance accuracy and efficiency

Laboratory calibration is suitable for new equipment acceptance, periodic verification, or high-precision measurement scenarios to ensure compliance with metrological regulations.

On site calibration is suitable for daily maintenance, troubleshooting, or scenarios where equipment cannot be disassembled, quickly verifying equipment performance.

Trend: With the improvement of portable device accuracy (such as ± 0.05 ℃ level dry well furnaces), the difference between on-site calibration results and laboratory results has narrowed (error ≤ 5.2 μ A, accounting for less than 7%), gradually becoming the mainstream choice.

In practical applications, it is recommended to combine the advantages of both: calibration and periodic verification are completed in the laboratory, and daily maintenance and troubleshooting are carried out through on-site calibration to balance accuracy, efficiency, and cost.