Apr 1, 2014

Get A Reliable Type K Thermocouple

By Jaclyn Hurley


How does one measure temperatures that are too hot for humans to be near? A traditional thermometer would be used for temperatures of around 200 degrees Fahrenheit and would destroy them if exposed to anything higher. Electronic thermometers can handle heat inside a computer but not a furnace at over 2000 degrees. The only option would be to use a type K thermocouple.

The sensors have been specially developed to with stand extremely harsh environments. Whether it's probing a blob of lava or drilling a whole a mile under the ice, thermocouples are the work horse in the temperature measuring department. Developed using two different types of thermo conducting wire with two ends joined together to create a joint. They produce a voltage as the temperature rises or falls.

They require no external power to produce these voltages due to the thermal gradient the materials experience. Commercially they are not expensive and are easy produced. Accuracy of the measure meant is due to the materials being used to produce the couples and the instruments used to measure the changes in the voltages. The more expensive monitoring devices can compensate for the differences in that may occur.

A wide range of temperatures can be measured using these devices and some factors can influence the measurement. One of these is the environment they are to be used in. If it is a chemically harsh atmosphere the couple can erode and the life span of it can be drastically reduced. By shielding it by means of a sheath it can be protected and thus its life span extended.

Some couples are designed to only be used in dry environments and thus any moisture can render the accuracy of the devices useless. There are limitations on the accuracy of the measurement as it gets closer to values of less than one degree Celsius. Thus it is difficult to measure accurately at these values. More sensitive monitoring devices would be required below this value.

The voltage is produced when heat or cold is applied to a thermo conducting metal. This conductor is subjected to a thermal gradient which then produces a voltage. By adding a second thermal metal on the same end with a varying degree of thermal gradient the difference between these two voltages can be detected and calculated.

The diameter of the wires influences the response time of the joint. The smaller the wire the quicker the temperature can be measured, but a trade off on this is the temperature range it can handle. The thicker it is the more temperature in can handle but is very slow to respond to the changes.

These couples can be attached in a permanent manner or by attaching it to a hand held probe. The hand held types are for lower levels of heat. These types tend to be shield from corrosive environments as to prolong the life of the probe. From very large to extremely same couples no matter what the application the actual thermocouple will remain the most popular in any industry.




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