2. Pressure thermometer: A pressure thermometer uses liquid, gas or saturated steam in a closed container to generate volume expansion or pressure change after being heated as a measuring signal. Its basic structure consists of three parts: temperature bag, capillary and indicator. It is one of the earliest methods applied to temperature control in production process. When the temperature is between -80℃ and 400℃, the heat loss is large and the response time is slow.
3. Mercury thermometer: It is an expansion thermometer. The freezing point of mercury is -38.87℃ and the boiling point is 356.7℃. Used to measure the temperature in the range of 0- 150℃ or 500℃. Can only be used as a tool for local supervision. Using it to measure temperature is not only simple and intuitive, but also can avoid the error of external remote thermometer.
Extended data:
Matters needing attention
1, first observe the range, dividing value and 0 point, and the measured liquid temperature cannot exceed the range.
2. All the glass bubbles of the thermometer are immersed in the measured liquid and do not touch the bottom or wall of the container.
3. The thermometer has thermal inertia and should be read after the thermometer reaches a stable state. When reading, you should read in the highest tangent direction of the temperature convex meniscus and look straight.
4. Immerse the glass bulb of the thermometer in the liquid to be measured, wait for a period of time, and then read after the pointer of the thermometer is stable.
5. When reading, the glass ball of the thermometer should be kept in liquid, and the line of sight should be flush with the upper surface of the liquid column in the thermometer.
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