A thermocouple is an apparatus that utilizes two different metal alloys to generate a voltage based on the temperature difference between the conductors. As a result, a thermocouple acts as a temperature sensor. It is made up of two different metal wires welded at one end and connected to a specific device at the other. When properly configured, they can display measurements in various temperatures.
Here are five advantages of thermocouple sensors in comparison to thermistors and thermometers:
The temperature scale of a Type K thermocouple temperature probe can be very wide depending on its design and materials. Some probes can measure temperatures as high as 2,200°F and as low as -58°F to 572°F.
In contrast, most thermistor and thermometer sensors have a limited range. Although some thermistors now have an upper limit of 572°F, their accuracy diminishes considerably above 300°F. Furthermore, a thermistor is damaged more quickly and irreparably at temperatures exceeding its stated limit.
As a thermocouple sensor is made by joining two different metals, it has more mechanical design options than other sensors. For tiny sensor assemblies, extremely fine gauge wire can be utilized.
Surface thermocouples are frequently made of flat wire. Heavy gauge wire can be used for extremely high-temperature probes or highly rugged assemblies. Thermocouple beads can also be used as fast-responding gas or air sensors. In comparison, other sensors are usually more constrained in terms of design and specifications.
In many applications, a quick response is essential. The mass or size of a temperature sensor has a direct impact on its speed. The larger the probe assembly or the sensor, the more the lag in the reading.
Due to technological advances, thermistors can be quite small. Yet, in comparison, a thermocouple can be made even smaller than the smallest thermistors. After all, a thermocouple sensor is composed of two wires, whereas a thermistor includes a coating and some carbon.
The sensing bead of the thermocouple can also fit inside a very thin tube, like a hypodermic needle. Even in a tube of 1/16″ diameter, a thermocouple bead can be directed further up into the tip of the probe than a thermistor. Due to this, a thermocouple sensor can equilibrate your goal temperature more quickly than a thermistor.
Compared to a standard industrial temperature probe, thermocouple sensors tend to be cost-effective. However, thermocouple sensors may be a little more expensive than some thermistors. This can be attributed to the higher cost of sturdier industrial-grade thermocouple probe materials.
However, some low-cost thermocouple options are also available. Thermocouple manufacturers may use low-grade wire to reduce costs, resulting in faster wire degradation and lower accuracy.
The thermocouple is more accurate than the thermistor. A thermistor contains lead, which diminishes its accuracy. Thermocouple accuracy can be further enhanced by permanently connecting the thermocouple probe assembly to the electronic circuit and calibrating it alongside the electronics in a “system calibration.” This process eliminates the interchangeability error of a thermocouple. As a result, increasing the overall measurement accuracy.
Thermocouple sensors can detect a vast range of temperatures, making them suitable for diverse applications. However, you must carefully read the specification claims before selecting a sensor.