How is an electrical contact bimetal thermometer calibrated?

The contact bimetal thermometer uses two metal sheets with different coefficients of expansion bonded together, and when the temperature changes, the metal pieces bend due to different degrees of expansion, thereby driving the pointer to deflect and trigger the electrical contact action.

Why do we need to calibrate? In addition to the fact that calibration can eliminate measurement errors caused by long-term use or environmental changes, and regular calibration can help identify potential problems and avoid equipment damage, many industries have clear requirements for the frequency and accuracy of calibration of temperature measurement equipment, and regular calibration is a necessary step for compliance.

Here are the steps and precautions for calibration:

The calibration procedure is explained in detail

1. Preparation: Check the appearance of the thermometer to ensure that there is no physical damage or corrosion. Prepare standard temperature sources (e.g., thermostats) and measuring devices (e.g., multimeters).

2. Set the temperature source:Submerge the thermometer completely in the thermostat to ensure that it is in adequate contact with the temperature source. Set the thermostat to the temperature point you want to calibrate and wait for the temperature to stabilize.

3. Record & Compare:Use a multimeter to measure the resistance value of the thermometer and record the actual temperature of the thermostat. The measured values are compared with the calibration curve of the thermometer to determine if there are any deviations.

4. Adjustment and correction: If deviations are found, adjust the internal mechanical structure or electronic circuitry of the thermometer according to the instruction manual provided by the manufacturer. For the electrical contact function, a multimeter or light is used to detect whether the contact is normally turned on or off at the set temperature.

5. Repeat the test: Repeat the above steps at different temperature points to verify the accuracy of the thermometer over the entire operating range.

6. Record the results: Record the calibration data for each temperature point, and attach information such as date, calibrator, etc., for subsequent reference.

Calibration Considerations

2. Standard equipment: Use high-precision standard thermometers and thermostats to avoid equipment errors affecting calibration results.

3. Regular maintenance: Establish a reasonable calibration interval according to the manufacturer's recommendations, usually every 6 months to 1 year.

4. Professional support: If the user does not have the conditions or experience to calibrate, it is recommended to contact a professional body or manufacturer for calibration.

The calibration of the contact bimetal thermometer is an important step to ensure its measurement accuracy and functional stability. Through standardized calibration procedures and regular maintenance, users can significantly extend the service life of their equipment and ensure its reliability in industrial applications.