control change of temperature indicators (in other words, the thermometer) is required in the laboratory or chemical research, to comply with the process technology in the production or maintenance of safety products.
logical to assume that the technology used in production, are not suitable for domestic purposes.Become acquainted with devices allowing measurements in various conditions.
Of course, the most common devices, allowing for temperature measurement, it thermometers.They include meteorological and laboratory, medical and electric-technical and Barometric, special and signaling.The total number of modifications of a few dozen.
Methods and apparatus for determining the temperature
thermometers familiar to us - only a small fraction of all existing in our time instruments or devices that are used in situations where you want the temperature measurement.Determination of thermal indicators may be carried out by several methods.The principle of operation of each unit is a specific parameter of the substance or body.Depending on the range in which the temperature measurement should be performed, using various devices.
- pressure.It allows you to monitor changes in temperature variations in the range of -160 degrees to +60.Devices called gauges.
- electrical resistance.It is the main principle of the electrical and semiconductor thermometers measure the resistance.The difference in the testimony of a semiconductor device allows to carry out measurements in the range from -90 to +180 degrees.Electrical devices capable of capturing from -200 to +500 degrees.
- thermoelectric effect is a leading property standardized or special thermocouples.Devices provide a definition of the type of standardized temperature range of -50 to 1600 ° C.Specialized devices are designed to work with critical high rates.Their working range - from 1300 to 2500 degrees.
- thermal expansion.Used in liquid thermometers, allowing them to determine the temperature range from -190 to +600.
- Thermal radiation.It underlies the operation of various types of pyrometers.Depending on the type of device, and varies the temperature range.Particular attention should be paid to the fact that these devices are only suitable for measuring high positive readings.In color pyrometer operating temperature limits up 1400 - 2800 degrees.For radiation devices, these figures will be equal to 20 - 3000 degrees.Photovoltaic devices record the temperature of 600 - 4000, and an optical pyrometer appreciate reading is within 700 - 6000 degrees.
Naturally, the question arises of how the physical properties allow for temperature measurement of air or hot metal.The gauges take a basis of the gas pressure or force of the liquid at certain temperatures.Thermometers and thermal imagers allow us to estimate the temperature of the surface of the object, seeing him coming from the thermal radiation (pyrometers show data in digital form, the imager provides a "picture" of the object and its temperature).Using the thermoelectric effect is the design of the thermocouple.By and large, the thermocouple is a closed electrical path of the two different conductors.Certain temperature exposure causes a certain tension.A similar principle is used in thermometers and resistance.
In general, methods of measuring temperature can be divided into contact and non-contact.Most expanse example method of contact - medical thermometer, non-contact - thermal imager.