Monday, July 1, 2013

The Type J Thermocouple Offers Many Benefits

By Claudette Lambert


There are several kinds of thermocouples available on the market today; these are all distinguished by means of charts and color coding. However there are four common calibrations, namely; K, J, E and T. Each one of these calibrations has a specific temperature range suited to their requirements and usage. The type J thermocouple is specifically used for any legacy temperature recordings and mainly found on control equipment.

Uses for J-thermocouples range from general functions to immersion in fluid and exposure to both air as well as gas. This product may also be custom made for usage in malleable solid infiltration and exterior or air temperature levels. As with the majority of thermocouples, these j-types could additionally be fitted inside connectors of either standard or miniature sizes.

These j-type connectors are not as popular as the k-type due to the fact that they have a much smaller temperature measurement range of between 750 degrees Centigrade, to -40. Additionally, they are more prone to corrosion as a result of the fact that they have iron based elements. Generally these couplets have a positive iron wire and then a copper-nickel alloy negative wire, this makes them relatively inexpensive and easy to find.

One critical aspect to keep in mind whenever dealing with thermo coupled instrumentation, is to make doubly sure that only the correct wiring is installed that is designed for that specific junction and functionality. To prevent any serious mistakes from occurring one must never splice J and K wires together as the wires inside the couplers are all polarity based or sensitive. Even though in the J and K type gauges the red wire found is negative but this does not mean that they can be joined as only like wires in both color and design can be safely joined.

Careful attention should also be paid to any outside sources of errors that will possibly impact their overall measurements or reading accuracy. Output signals are in milli- volt measurements and generally one will find they have small voltage to temperature sensitivity. Therefore the foremost sources of error for defined measurements to allow for are thermocouple malfunctions, noise errors and gain errors, accuracy balance as well as cold-junction return.

These small temperature gauges are manufactured from two dissimilar metals that are welded together and generate electromotive forces (EMF) caused by temperature fluctuations at the point of connection. Essentially, this process is known as the Seebeck effect or thermoelectric effect. It is one of the widest used means by which temperature of this sort is measured.

In order to eliminate possible errors the manufacturers have a configuration guide that will ensure that all components are used for the correct application. Furthermore, they also offer technical support from expert engineers for any clients. Guidelines seem to be similar but there may be slight differences between manufacturers.

Specific thermocouples should have exclusive control programs designed to ensure all readings are truthful. Recalibration does occur when the thermocouple material is altered during any type of magnetic sway or really high temperatures. It must be stipulated that type j thermocouple is not suitable for any type of application where temperatures exceed 760 degrees C.




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