Thermocouples are constantly secretly working all around you. But what are thermocouples and how do they work? In simple terms, a thermocouple is a sensor which measures temperature. It produces a unique voltage at a given temperature which can then be measured and interpreted by a thermocouple thermometer. They are used for a range of measurement and control tasks, widely used in science and the manufacturing industry.
Thermocouple thermometers are used for temperature measurement in kilns, diesel engines, ovens and industrial processes. Thermocouple works because of the thermoelectric effect, which is when a conductor generates a voltage when subjected to a thermal gradient. A thermocouple can be calibrated in a number of different ways, but there are four which are more common than others. These most common calibrations are referred to as calibration J, K, T and E. Each one has a different temperature range and environment that it is useful for.
The maximum temperature which a thermocouple will measure can be increased by making the wire thicker. When selecting a thermocouple, as with most products, it is best to follow a set of guidelines to ensure you purchase one to suit your needs. The first thing that you will want to do when selecting a thermocouple to use is to check the temperate range that it covers. The chemical resistance and sheath material, as well as the abrasion and vibration resistance, are factors which should be considered.
You may also want to make sure that you are aware of what installation requirements the thermocouple has, as it may be required to be compatible with existing equipment for example. The type of thermocouple is also a key. The three main sub-categories are Grounded, Ungrounded and Exposed thermocouples. A Grounded thermocouple has the wires physically attached to the inside of the probe wall which can help with the direct reading of temperatures. An Ungrounded thermocouple is isolated from the probe wall, which offers the benefit of electrical isolation.
An Exposed thermocouple protrudes out of the tip or the sheath and is therefore exposed to all of the surrounding environment. Depending on how and where you are trying to measure temperature will depend on what thermocouple is best for your needs as well as what metal combination and calibration that you will wish to use. Various different thermocouples will offer better or more accurate readings but only in certain conditions. Therefore it may be required to sacrifice response time or speed of reading due to the requirements of the environment in which you are measuring in.
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