Common Calibration Methods for Precision Digital Thermometers
Precision digital thermometers usually use platinum resistance as the temperature-sensing element. It is an international trend to replace standard mercury thermometers with corresponding platinum resistance sensors for such precision digital thermometers. Therefore, it is necessary to study its calibration methods.
Resistance Measurement Calibration Method Calibration Method
1. Preparation before calibration
If the thermometer has a calibration function, set its working mode to calibration mode before turning on the machine, and then connect the first-class standard resistance in the constant temperature bath to the thermometer according to the range of the thermometer, then turn it on, and wait for the temperature to be measured. After the meter is stable, input the value in the standard resistance verification certificate into the thermometer, and then turn it off after it is stable; set the working mode of the thermometer to the measurement mode, and turn it on to prepare for calibration. Start the machine and input and store the relevant data in the platinum resistance thermometer certificate as required.
2. Selection of calibration points
Generally, 25Ω and 100Ω measurement points are selected, and other measurement values can be selected as required.
3. Calibration
According to the measuring range of the thermometer, connect the standard resistance to the thermometer respectively, and read the resistance value of the thermometer after the thermometer is stable.
4. Calibration method
Use the fixed-point method or the comparison method. When using the comparison method to calibrate, insert the standard platinum resistance thermometer and the sensor of the thermometer to be calibrated into the constant temperature bath, and start reading the readings of the standard thermometer and the thermometer to be calibrated after the temperature is stable, and then read again at intervals of 1 to 2 minutes. 2 times in total.
