What is the principle of Vapour pressure thermometer?

What is the principle of Vapour pressure thermometer?

In vapour pressure thermometers a highly volatile liquid is used, but only partially occupies the thermometer volume. The liquid begins to vaporize and fills the rest of the volume with steam. As a result, the pressure rises until an equilibrium between the liquid phase and the gas phase is reached.

What is the principle of bimetallic thermometer?

A bimetallic thermometer works by using two basic properties of metal: The thermal expansion property of the metal. The coefficient of thermal expansion of different metals is different for the same temperature.

What is a vapor thermometer?

Definition of vapor-pressure thermometer : a thermometer in which the variable saturated vapor pressure of a volatile liquid is used as a measure of the temperature and which thus has the advantage over some other types of thermometers of being free from errors due to bulb expansion.

How does the thermometer work?

When the tip of the mercury thermometer touches the material it is measuring, the material conducts heat energy to the mercury. Then the mercury expands as it turns into a liquid and begins to rise up the tube. The place where the mercury stops on the scale is where you can take the reading of the temperature.

Which liquid is used in Vapour pressure thermometer?

21.3. 4 Vapor Pressure Thermometers

What is the range of Vapour pressure thermometer?

These thermometers are very sensitive but the scale is not linear. The measurement accuracy is 1%. The typical temperature range is from – 20° C to 280° C depending on the nature of the gaz (Butane propane, ammonia…).

What is the working principle of thermocouple?

The operating principle of the thermocouple is based on the Peltier effect. The thermocouple circuit consists of two metals joined together to form two junctions of different temperatures. A Peltier emf is generated due to the difference in temperatures of the two junctions of the circuit.

What is the principle of bimetallic strip?

Definition: A bimetallic strip works on the principle of thermal expansion, which is defined as the change in volume of metal with the change in temperature.

What is the working principle of a mercury thermometer?

Mercury thermometers are based on the principle that liquids expand when heated and contract when cooled. So, when the temperature increases, the mercury expands and rises up the tube and when the temperature decreases it contracts and does the opposite.

How is a thermocouple used?

A thermocouple is a device for measuring temperature. It comprises two dissimilar metallic wires joined together to form a junction. When the junction is heated or cooled, a small voltage is generated in the electrical circuit of the thermocouple which can be measured, and this corresponds to temperature.

What is the name of temperature measuring instrument Vapour pressure thermometer?

Pressure Gauge Thermometer. It is temperature measuring device whose operation is based on thermal expansion of a liquid. These are also called as fluid-expansion thermometers. Liquid filled thermometers have range from -30° C to 250° C.

What is the working principle of a vapour pressure thermometer?

Vapour pressure thermometer. Operating Range: up to 300°C. Method used: Expansion of Liquids. If temperature increases, liquid expands in volume. This change in volume of liquid is directly proportional to change in temperature. Liquid in glass type thermometer is a thick-walled glass tube casing.

Why is the scale of a vapour pressure thermometer not subdivided?

Since the vapour pressure curves are not linear, the scale for vapour pressure thermometers is not evenly subdivided. Due to the exponentially increasing vapour pressure curves, the scale distances increase with higher temperature, so that the measurement sensitivity and accuracy increases as a result.

What is a pressure thermometer made of?

Liquid-in-metal or pressure thermometers consist of a sensitive bulb, an interconnected capillary tube and a pressure measuring device such as a Bourdon tube. They follow an equation similar to the Eqn (11.1), which has been discussed for liquid-in-glass thermometers, i.e.

What is the accuracy of a press pressure thermometer?

Pressure thermometers can be used to measure temperatures in the range between −250 °C and +2000 °C and their typical inaccuracy is ±0.5% of full-scale reading. However, the instrument response has a particularly long time constant.