Termometer Air Raksa

Mercury thermometer function
The thermometer is a device for measuring temperature. Thermometer analog thermometer can also be called as a manual, because the way the reading

still manual. The use of mercury as the main ingredient thermometer because the mercury expansion coefficient relatively constant so that changes in volume due to increase or decrease in temperature is almost always the same. But there are also some families thermometer contains alcohol with the addition of red dye. Thermometer is safer and easier to read.]

A special type of mercury thermometers, called a maximum thermometer, working with the valve on the neck of the tube near the bulb. When the temperature rises, the mercury is pushed upwards by the force through the expansion valve. When the temperature drops of mercury retained in the valve and can not return to the bulb to keep the mercury in the tube. The reader can then read the maximum temperature for a predetermined time. To restore its function, the thermometer should be swung hard. This thermometer medical thermometer-like design.

Mercury will freeze at a temperature of -38.83 ° C (-37.89 ° F) and can only be used at temperatures above it. Mercury, unlike water, does not expand when frozen so it does not break the glass tube, making it difficult to observe when it freezes. If the thermometer contains nitrogen, the gas may flow down into the column and trapped there when the temperature rises. If this happens the thermometer can not be used to return to the initial conditions. To avoid this, the mercury thermometer should be put in a warm place at temperatures below -37 ° C (-34.6 ° F). In the area where the maximum temperature is expected to rise above - 38.83 ° C (-37.89 ° F) thermometer that uses a mixture of mercury and thallium may be used. This thermometer has a freezing point of -61.1 ° C (-78 ° F).

Measurement of Mercury Thermometers

Generally use a mercury thermometer scale Celsius temperature and Fahrenhait. Celsius used two important points on the scale: the temperature when the ice melts and the water evaporation temperature. Ice melt at the same calibration mark on the thermometer in the steam of boiling water. When the thermometer out of water vapor, the height of the mercury down slowly. This relates to the rate of cooling (and the expansion of the glass tube). So pegukuran celsius temperature using the temperature of melting and freezing temperatures are not.

Celsius is the boiling point of 0 ° C (212 ° F) and freezing at 100 ° C (32 ° F). But other researchers, Frenchman Jean Pierre Cristin proposed version of the reverse-Celsius scale the freezing point at 0 ° C (32 ° F) and boiling at 100 ° C (212 ° F). He named it Centrigade.

The workings of Mercury Thermometers

This device consists of a capillary tube using a glass material containing mercury at the lower end. For measurement purposes, the pipe is made in such a way that the vacuum. If the temperature increases, the mercury will expand up to the top of the pipe and provide clues about the temperature gauge in accordance with a predetermined scale. The general way of working is as follows;

Prior to the change in temperature, the volume of mercury is in the initial conditions.
Temperature changes in the environment around the mercury thermometer responded with volume changes.
The volume of mercury will expand if the temperature increases and will shrink when the temperature decreases.
The scale of the thermometer will indicate the temperature corresponding state of the environment.

Calibration Mercury Thermometers

Calibration is the process of verifying that an accuracy of measuring instruments in accordance with the design. Calibration is usually done by comparing a standard that is connected with national and international standards and certified reference materials.

Thermometer calibration process include:

Place the thermometer in the water cylinder is being melted and check points around the thermometer when the liquid water entirely. This point is the freezing point of water.
In the same way, mark the point when the thermometer throughout the entire boiling water when heated.
For the length of the above two points into one hundred equal parts.