Common methods used to calibrate precision digital thermometers
Precision digital thermometers usually use platinum resistors as temperature sensing elements. It is an international trend to replace standard mercury thermometers with corresponding platinum resistance sensors for such precision digital thermometers. Therefore, research on their calibration methods is necessary.
Calibration methods for resistance measurement calibration methods
1, Preparation work before calibration
If the thermometer has calibration function, set its working mode to calibration mode before starting up. Then, connect the first-class standard resistance in the constant temperature bath to the thermometer according to the range of the thermometer, and turn on the thermometer. After the thermometer stabilizes, input the value in the standard resistance calibration certificate into the thermometer. After stabilizing, shut down the thermometer; Set the working mode of the thermometer to measurement mode and prepare for calibration upon startup. Turn on the device and input and store the relevant data from the platinum resistance thermometer certificate as required.
2, Selection of calibration points
Generally, 25 Ω and 100 Ω measurement points are selected, and other measurement values can be selected as needed.
3, Calibration
Connect standard resistors to the thermometer according to its range, and read the resistance value of the thermometer after it stabilizes.
4, Calibration method
Using fixed-point or comparative methods. When using the comparative method for calibration, insert the standard platinum resistance thermometer and the temperature sensor of the calibrated thermometer into the constant temperature bath. After the temperature stabilizes, start reading the readings of the standard thermometer and the calibrated thermometer, and repeat the reading every 1 to 2 minutes, a total of 2 times before and after.
