A thermocouple is a special thermoelectric device that accurately measures temperatures. It consists of two dissimilar metals linked so that the potential difference created between the contact points gives the temperature. The principle involved is that when the junction is either heated or cooled a voltage is generated which is the correlated back to temperature. These devices are used to measure or control temperature for different appliances. There are many thermocouple types which are used in different applications.
A number of the thermocouples sold in the market are interchangeable and are easily affordable. They are usually accompanied with standard connectors. These devices can be used for different temperature ranges and have proved to be the most efficient sensors. The main disadvantage of these devices is their limited accuracy since the errors usually involve several degrees Celsius.
There are many combinations of alloys that can be adopted in the formation of the conductors. The selection of the combinations is determined by various factors such as availability, cost, chemical properties, convenience, stability, output and melting point. The various types of thermocouples are suited for different uses. The main consideration made in the selection of a specific kind is sensitivity required and the range of the temperature to be measured. It is also important to consider the inertness and the magnetic properties of the thermocouple material.
There are four different categories of all possible combinations and are represented by capital letters. These classifications are the upper crust, home body, exotic and rarified class. The home body mainly consists of standard metals while the upper crust is made up of all platinum combinations. The exotic class consists of special rare metals which are intended for special applications. The rarified is made up of refractory metals and has no alpha codes associated with it since it less frequently used.
There are a variety of standard thermocouples each with its own unique specifications that adapt it for a specific application. The widely known is the type K thermocouple which is used for multiple uses. It consists of two electrodes, the positive being chromel while the negative is made of alumel. The values obtained are very accurate and it is dependable. It is efficient for temperatures not exceeding 1260 degrees Celsius. There are several precautions that have to be taken when using them. They should be protected from damage and kept clean at all times.
Type E thermocouples are suitable for use in a vacuum or in oxidizing and inert atmospheres. The recommended temperature for its operation is 900 degrees Celsius. It is characterized by a very high electromotive force output. The thermocouples under class J do not need protection although it is recommended for cleanliness purposes. This category is used at 760 degrees. Type N is constructed with nickel conductors and can withstand temperatures as high as 1260 degrees Celsius. This kind is durable and offers more resistance in oxidizing atmospheres. The thermocouples that fall under category T is suitable for measuring low temperatures.
The conductors of the B, R and S types are made of platinum or a rhodium and platinum alloy. They have the highest degree of stability but their sensitivity is very limited. Their limited sensitivity and high costs makes them suitable for the measurement of very high temperatures.
The various thermocouple types are widely applied in industry and science. They are used to measure temperature in diesel engines, gas turbine, kilns and in industrial processes. They are not suitable in situations involving small temperature differences which require greater accuracy. In these applications it is appropriate to use thermistors, resistance temperature detectors and special silicon temperature sensors.
A number of the thermocouples sold in the market are interchangeable and are easily affordable. They are usually accompanied with standard connectors. These devices can be used for different temperature ranges and have proved to be the most efficient sensors. The main disadvantage of these devices is their limited accuracy since the errors usually involve several degrees Celsius.
There are many combinations of alloys that can be adopted in the formation of the conductors. The selection of the combinations is determined by various factors such as availability, cost, chemical properties, convenience, stability, output and melting point. The various types of thermocouples are suited for different uses. The main consideration made in the selection of a specific kind is sensitivity required and the range of the temperature to be measured. It is also important to consider the inertness and the magnetic properties of the thermocouple material.
There are four different categories of all possible combinations and are represented by capital letters. These classifications are the upper crust, home body, exotic and rarified class. The home body mainly consists of standard metals while the upper crust is made up of all platinum combinations. The exotic class consists of special rare metals which are intended for special applications. The rarified is made up of refractory metals and has no alpha codes associated with it since it less frequently used.
There are a variety of standard thermocouples each with its own unique specifications that adapt it for a specific application. The widely known is the type K thermocouple which is used for multiple uses. It consists of two electrodes, the positive being chromel while the negative is made of alumel. The values obtained are very accurate and it is dependable. It is efficient for temperatures not exceeding 1260 degrees Celsius. There are several precautions that have to be taken when using them. They should be protected from damage and kept clean at all times.
Type E thermocouples are suitable for use in a vacuum or in oxidizing and inert atmospheres. The recommended temperature for its operation is 900 degrees Celsius. It is characterized by a very high electromotive force output. The thermocouples under class J do not need protection although it is recommended for cleanliness purposes. This category is used at 760 degrees. Type N is constructed with nickel conductors and can withstand temperatures as high as 1260 degrees Celsius. This kind is durable and offers more resistance in oxidizing atmospheres. The thermocouples that fall under category T is suitable for measuring low temperatures.
The conductors of the B, R and S types are made of platinum or a rhodium and platinum alloy. They have the highest degree of stability but their sensitivity is very limited. Their limited sensitivity and high costs makes them suitable for the measurement of very high temperatures.
The various thermocouple types are widely applied in industry and science. They are used to measure temperature in diesel engines, gas turbine, kilns and in industrial processes. They are not suitable in situations involving small temperature differences which require greater accuracy. In these applications it is appropriate to use thermistors, resistance temperature detectors and special silicon temperature sensors.
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