Temperature measurement of sanitary ball valve < / a >:

1. According to the operating conditions, glass tube liquid thermometer, bimetal thermometer, resistance thermometer or thermocouple can be used for temperature measurement. All the above thermometers can be inserted directly into the pipe or into the casing, except that the glass tube liquid thermometer must be inserted inside and outside the casing. When the temperature is lower than 150 ℃, the temperature measuring device should be directly inserted into the pipeline without additional casing.

2. When making any temperature measurement, the following measures shall be taken:

1. Except for the measured medium, there should be no large heat transfer between the temperature measuring device and the outside due to radiation or conduction.

2. The adjacent part of the insertion point and the exposed part of the temperature measuring device shall be insulated.

3. For small diameter pipes, the temperature measuring device shall pass through the center line of the pipe; when the pipe diameter exceeds 300 mm, it shall be inserted into the medium flow at least 150 mm depth.

4. On pipelines conveying compressible fluid, the temperature measuring device shall be installed at the place where the maximum medium velocity does not exceed 30 m / s for any flow measurement. If this installation is not possible, it may be necessary to correct the temperature reading to the appropriate static or full temperature.

5. The temperature measuring device shall be inserted in such a way that the measured temperature can represent the temperature of the flowing medium as described in the test arrangement.

3. When a glass tube mercury thermometer is used to measure temperature, the thermometer shall have a graduated rod. When the difference between the measured temperature and the ambient temperature is greater than 5 ° and the mercury is exposed, the exposure rod correction should be made or the exposed rod thermometer should be used.

4. When thermowells are used, they should be thin-walled and their diameter should be as small as possible. There should be no corrosion or debris on the surface of the casing, and appropriate fluid should be filled in the casing, but mercury should not be used. Because the evaporation pressure of mercury is very low, it will bring serious harm to people's health. Of course, if mercury is used for this purpose, appropriate precautions must be taken.

5. If thermocouples are used, they shall have welded hot ends and shall be calibrated with their external leads for the intended range of use. The thermocouple shall be made of materials suitable for the temperature and medium to be measured. The electromotive force should be measured by potentiometer or millivoltmeter. The cold end of the thermocouple shall be made up of an ice bath (reference standard) or by adding a compensation circuit to the potentiometer.