Thermocouples Manufacturing and Engineering

Not just everyone discusses thermocouples with their friends, coworkers and associates. But if you're in an industry where regular temperature measurement is critical, suddenly these fancy little temperature sensor devices become interesting. If you're involved in manufacturing or engineering, chances are that you recognize the importance of a high performance thermocouple.

Without measuring temperatures accurately, thousands of dollars worth of product can be ruined. This is where thermocouples come in. They are used frequently in manufacturing and engineering industries. Other temperature measurement devices and accessories often used (either alongside thermocouples or instead of them) include thermo wells, transmitters, RTD sensors, temperature transmitters, sensor accessories, and connection heads.

Dozens of industries, from engineering to manufacturing, use thermocouples regularly. Without these inexpensive devices, manufacturing as we know it would not exist. Plastics, metals, cosmetics, food manufacturing, glass, pharmaceuticals, chemical production … these items are all very temperature sensitive during the manufacturing process. By indicating temperature read outs, Thermocouples standardize the manufacturing process, increase safety during manufacturing, and allow various products to be made to uniform quality specifications.

Types of Thermocouples

If you are selecting a thermocouple for use or purchase, you should consider 3 main things. First, decide whether you need a bare wire "bead" thermocouple or a built in thermocouple probes. Secondly, you must consider the probe construction and the thermocouple's insulation. Third (which many people regard as the most important), you must decide on which the "type" of thermocouple would be optimal for the use you need it for. The various "types" of a thermocouple are made up of different metals, and each has different temperature measurement abilities and/or limitations.

Thermocouples come in many different varieties, called "types." Among the types, 8 standard ones are the most popular. These are: Type B (Platinum and Rhodium), Type E (Chromel and Constantan), Type J (Iron and Constantan), Type K (Chromel and Alumel), Type R (Platinum and Rhodium), and Type S (Platinum and Rhodium), and Type T (Copper and Constantan).

Usually the Type R (Platinum and Rhodium), and Type S (Platinum and Rhodium), and Type B (Platinum and Rhodium) Thermocouples are grouped together, because they are all considered "noble" metal Thermocouples and share a lot of similarities.

In the following paragraphs, you will find some useful information on each of the 8 most common types of Thermocouples.

Type B Thermocouples (Platinum and Rhodium)

This type of thermocouple is among the most stable of Thermocouples. Type B is Platinum and Rhodium, like the other 2 "noble" Thermocouples. However, due to certain limitations in sensitivity, this type of thermocouple is most commonly employed to measure fairly high temperatures (above 300 degrees Celsius). Some of the noble Thermocouples give identical readings for temperatures between 0 degrees Celsius and 42 degrees Celsius, so they are obviously not at all useful for lower temperatures.

Type E Thermocouples (Chromel and Constantan)

This is a very high output thermocouple—among the highest of Thermocouples. It is less stable than the "noble" Thermocouples (which are made of Platinum and Rhodium, and perform poorly at low temperatures), but has many advantages. Type E Thermocouples (made of Chromel and Constantan) can be used at low temperatures. Their range of accuracy is generally accepted as -270 degrees Celsius to +1100 degrees Celsius. However, keep in mind that if you use a Type E at temperatures above 800 degrees Celsius, it will wear out faster and have a greater margin for error. Type E Thermocouples are also useful for their non-magnetic quality. The positive leg on a Type E thermocouple is Chromel and the negative leg is Constantan. The Type E Thermocouples are often used for cryogenic applications, chemical applications, pharmaceutical applications and manufacturing, and to drive analog meters.

Type J Thermocouples (Iron and Constantan)

Type J Thermocouples have a more limited range than some of the Thermocouples (-40 degrees Celsius to +750 degrees Celsius). They are inexpensive and easy to read, with good thermal sensitivity, and are generally known to be good for medium temperatures. Many people recommend only using Type J Thermocouples up to temperatures of 350 degrees Celsius. Type J aren't as popular as the similar Type K. Type J Thermocouples are most commonly used with old types of equipment that don't work with more updated types of Thermocouples (such as Type K). Type J Thermocouples are made of Iron and Constantan.

Type K Thermocouples (Chromel and Alumel)

Often called the "all purpose" thermocouple, the Type K Thermocouple is cheap, efficient, and widely available. It's good for reading a wide medium-range of temperatures, from -200 degrees Celsius to +1200 degrees Celsius. Experts recommend using a Type K thermocouple unless you absolutely must get another Type. Type K is made up of Chromel and Alumel.

Type R Thermocouples (Platinum and Rhodium)

This type of thermocouple is among the most stable of Thermocouples. Type R is comprised of Platinum and Rhodium, like the other 2 "noble" Thermocouples. However, due to certain limitations in sensitivity, this type of thermocouple is most commonly employed to measure fairly high temperatures (above 300 degrees Celsius). Some of the noble Thermocouples give identical readings for temperatures between 0 degrees Celsius and 42 degrees Celsius, so they are obviously not at all useful for lower temperatures.

Type S Thermocouples (Platinum and Rhodium)

This type of thermocouple is among the most stable of Thermocouples. Type S is a junction of Platinum and Rhodium, like the other 2 "noble" Thermocouples. However, due to certain limitations in sensitivity, this type of thermocouple is most commonly employed to measure fairly high temperatures (above 300 degrees Celsius). Some of the noble Thermocouples give identical readings for temperatures between 0 degrees Celsius and 42 degrees Celsius, so they are obviously not at all useful for lower temperatures.

If you are looking for premium quality RTD Sensors and Thermocouples at affordable prices, take a look at what Pyromation has to offer. Pyromation offers a full range of products, ranging from durable industrial thermocouples to highly precise RTDs, at affordable prices. Other good companies that sell quality thermocouple and RTD Sensors include Nanmac and Omega.


More by this Author


Comments

No comments yet.

    Sign in or sign up and post using a HubPages Network account.

    0 of 8192 characters used
    Post Comment

    No HTML is allowed in comments, but URLs will be hyperlinked. Comments are not for promoting your articles or other sites.


    Click to Rate This Article
    working