How to use and precautions for junction thermometer

1. How to use the junction thermometer

The contact thermometer is the most widely used temperature sensing element in experiments. It often forms a complete temperature control system with a heater. In this system, the main function of the contact thermometer is to detect the temperature of the constant temperature medium and send the temperature information to the relay at any time to control the on and off of the heating switch. It is the sensing hub of the constant temperature bath and the key to improving the accuracy of the constant temperature bath. The use of the contact hygrometer is as follows:

1. Insert the junction thermometer into the thermostatic bath and connect the two wires to the relay terminals.

2. Loosen the fixing screw on the adjusting cap of the junction thermometer, rotate the adjusting cap, and adjust the standard iron to a temperature slightly lower than the temperature to be kept constant.

3. Switch on, the indicator light of the thermostat will light up (indicating the start of heating), turn on the stirrer and stir at medium speed. When the mercury is heated to the point of contact with the uranium wire, the indicator light will go out (indicating the end of heating), and then read the reading of the 1/10℃ thermometer. If it is lower than the desired constant temperature, slowly adjust the standard iron to rise until the desired constant temperature is reached. Then fix the adjusting nut.

2. Precautions for use

1. The junction thermometer can only be used as a temperature sensor, not as a temperature indicator (because the temperature scale of the junction thermometer is very rough). The temperature of the constant temperature bath must be indicated by a 1/10 degree Celsius thermometer.

2. When the junction thermometer is not in use, the temperature should be adjusted to above room temperature and stored.

3. Avoid sudden cooling or heating to prevent cracking.