Thermocouples are the most basic of all thermometers. They are the most inexpensive and the simplest to use.
Thermocouples consist of a wire with a tip that produces a small electric current when one end is heated, and the other end is cooled.
While thermocouples are widely used in industrial applications, they are also used in laboratories.
In this post, we’ll show you the three types of thermocouple and their uses.
Types of Thermocouples
Beaded Wire Thermocouple
This is the most basic type of thermocouples. They’ve been so well-received by customers because they offer a superb blend of versatility, high value and ease of use. The beaded thermocouple’s small design enables fast response times and outstanding adaptability in a wide range of conditions.
A beaded thermocouple comprises two pieces of thermocouple wire that have been soldered together to form a bead. As a result of the bead being exposed, there are various applications to which a beaded thermocouple is limited.
To avoid oxidation or corrosion of the thermocouple alloy, do not use the beaded wire thermocouple with liquids that are likely to react with it. Problems might arise with metal surfaces as well. Surfaces made of metal, particularly pipes, are frequently utilised as grounding electrodes in electrical systems. It is possible that the thermocouple measurement may be indirectly affected by the connection that is made to an electrical system. The most common use of beaded thermocouples is the measurement of gas temperatures.
Surface Probe Thermocouples
The term “surface probe” refers to a thermocouple probe with a flat and thin connection. The vast majority of temperature sensors are incapable of reliably measuring the temperature of a solid object. To receive accurate results from the measurements, the sensor’s entire measuring area must be in contact with the surface. Many difficulties arise while working with rigid sensors and hard surfaces.
Using thermocouples made of malleable metals, the junction can be moulded into a flat and thin surface such that it has as much contact with unyielding solid surfaces as possible. These thermocouples are an excellent choice for determining surface temperatures. The thermocouple can also be integrated into a mechanism that spins, making it appropriate for use in applications where the temperature of a surface in motion needs to be determined.
Depending on their design, surface probe thermocouples can measure temperatures ranging from below zero to more than 1200°C. They come in various forms, including clip and clamp-on thermocouples, adhesive patches, bolt-down washers and cement on. This type of thermocouple is often precise to within +/-1°C over a wide temperature range. However, accuracy can be affected by factors such as design quality, proper mounting and product application.
Thermocouple Probe
A thermocouple probe is nothing more than a thermocouple wire enclosed in a casing. The wall of the tube into which the probe is put is referred to as the sheath of the probe. Stainless steel and Inconel® are the common materials used for sheath.
The material used to construct the thermocouple probe’s sheath dictates the probe’s properties. A stainless-steel sheath, for example, results in a probe with little worries about chemical compatibility. On the other hand, Inconel can withstand far higher temperatures than stainless steel.
There are three distinct options for the thermocouple probe’s tip; grounded, ungrounded and exposed. An electrically grounded tip, also known as a tip that is in direct touch with the sheath wall, provides quick readings but is susceptible to electrical interference, which can lead to false readings. Electrical interference can be reduced by using an ungrounded or insulated tip, which is physically separated from the sheath. The most accurate sort of tip for monitoring air temperature is an exposed tip, also known as a tip that protrudes from the sheath. Thermocouple probes have one more advantage: some variants can be connected to computers via USB ports. This is a highly convenient feature.
So, What are the 3 Types of Thermocouples?
Thermocouples are wires with tips that produce an electric current when heated and cooled. There are 3 main thermocouples types: beaded wire thermocouple, surface probe thermocouples and thermocouple probe. A beaded wire thermocouple is the most common and popular thermocouple because it perfectly blends versatility, high value and ease of use. Surface probe thermocouples are used to measure the temperatures of flat surfaces.
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