Thermocouple Sensors

thermocouple sensorsWhat Is a Thermocouple Sensor? A thermocouple sensor is a specialized temperature measure that provides accurate readings in settings where normal thermometers can’t function well. Probes, beaded wire thermocouples, and surface probes are some of the most common types of thermocouple sensors, and their design reflects the type of measurements they can take. For example, we recommend using a probe when you need to check the air’s temperature.

How Do Thermocouples’ Temperature Sensors Work?

Thermocouples’ temperature sensors use two wires welded together to gauge a substance’s temperature. These wires are made of different metals and are only joined at one end. The difference in metals produces an electrical circuit when they encounter cold or hot substances, and the thermocouple’s thermometer converts the voltage into a temperature reading.

Different thermocouple sensors take their readings in different ways. Some probes’ sheaths can simply be removed to start measuring, while others must be submerged in the material in question. Similarly, the formula for turning voltage units into degrees varies.

Why Use Thermocouples?

Paper producers, pharmaceutical manufacturers, and mining operations rely on thermocouple sensors; so do many other industries that need to check temperatures regularly. Their widespread use is because they are inexpensive. Resistance temperature detectors perform similarly to thermocouples but generally cost twice as much. Also, thermocouples do not require power supplies, batteries, or specialized connectors, driving down their installation costs.

Thermocouples’ ability to withstand extreme temperatures also explains their popularity. These devices can easily measure substances that are hotter than 1,202 degrees Fahrenheit, which is magnesium’s melting point. They function well in cold environments, too, making them ideal for pharmaceutical manufacturing and information technology applications.

Finally, we recommend thermocouples to our customers because they last a long time. Their sheaths offer protection from chemicals and other corrosive materials, and we choose their wires’ material carefully to maximize their longevity.

How To Choose a Thermocouple

If you’re buying a thermocouple for the first time, start by thinking about the temperatures that the device must withstand. We optimize different thermocouple calibrations for different temperatures, and choosing the wrong calibration could lead to inaccurate measurements. For example, if you’re working with cryogenic environments, you need a type T thermocouple. If you’re using the same thermocouple for several substances, a K type thermocouple is better.

Next, consider the environment in which you’re going to use the instrument. Is the substance full of electrical activity? If so, we recommend an ungrounded thermocouple. Is the pressure extremely high, or is the substance full of hazardous materials? If so, an unexposed thermocouple is our top choice.

Your required response speed also affects your decision. Ungrounded thermocouples’ readings are the slowest. However, grounded thermocouples are not effective at preventing the thermocouple from forming an electric circuit with its sheath. Similarly, exposed thermocouples calculate temperatures the fastest, but without sheaths, they erode quickly in corrosive environments.

Finally, think about your plant’s current setup for thermocouples. If you want to mount your thermocouple on a wall already drilled with holes for the instrumentation, use those holes’ sizes to choose your sensor’s measurements. Similarly, if your team knows how to use one type of thermocouple, switching to another style may be difficult.

Common Types of Thermocouples

There are eight main types of thermocouples, but the K type thermocouple and the J type thermocouple are the most popular. K type sensors are effective across many temperatures, and they’re popular choices for hospitals and food production. We recommend using a J type thermocouple if you’re measuring the temperature of a reducing environment or a vacuum.

The K type, J type, along with type T and E are what are known as “Base Metal” thermocouples. The types depend on variables such as temperature range, durability, resistance to vibration, chemical resistance and more. Contact Hi-Watt Inc. to find out which type of thermocouple will suit your application.

Range of Applications

These industrial temperature sensors can be utilized for direct process insertion or with thermowell and protection tubes. A wide variety of design, sheath material and diameter selections are available to suit a comprehensive range of applications.

Mineral insulated thermocouples are rapid responders with intense temperature capacities and magnesium oxide insulation. Standard industrial thermocouples can feature Teflon and fiberglass insulated leads. They vary by temperature range and exterior diameter.

Hi-Watt supplies the most reliable temperature sensors from globally respected manufacturers. Our industrial temperature sensors and sensing instruments are available in general application (tube and wire), mineral insulated metal sheathed, high temperature, base metal, surface temperature and other thermocouple categories.

Thermocouple Accessories

Hi-Watt offers a full line of accessories to accommodate your varying sensor requirements such as thermocouple wire and more. These support products can be used to install and maintain your temperature sensor assemblies. Give us a call today for a quote.

  • Standard and Mini Connectors
  • Jack Panels
  • Connection Heads
  • Compression Fittings
  • Bayonet Adapters

Thermocouple Temperature Sensor for Processing

Our leading lines of thermocouple temperature sensors come with broad temperature range capabilities. Thermocouple devices are widely deployed for process and industry applications due to their measurement ranges and durable construction. Their specifications include various calibrations, with J type thermocouples and K type thermocouples commonly used. High temperature calibrations, such as R and S, are also available.

Factors to review in selecting a thermocouple include: temperature range, chemical resistance, system compatibility, and installation requirements. Specific calibrations coordinate with specific temperature ranges. Maximum temperatures are dictated by wire diameter. Call Hi-Watt in Detroit, Michigan to determine the unique advantages our sensors will bring to your company.


NTC Thermistor vs Thermocouple

Similar to a NTC thermistor, a thermocouple is an accurate way to measure resistance and temperature. Thermocouples use two dissimilar metals that are conductive and connected at a single point. This forms two electrical junctions: measuring and reference, also known as hot and cold.

K-type thermocouples use these junction points to maintain two different temperatures and produce low DC voltage that is temperature dependent. This thermo-electric voltage allows the sensor to measure the resistance, which is used to measure the temperature.

As an all-purpose sensor, thermocouples are capable of extreme temperatures ranging from -200 degrees Celsius to 1,250 degrees Celsius. Despite the larger temperature range, these sensors aren’t always as accurate due to calibration drift.

Compared to an NTC thermistor, thermocouples have a shorter and less predictable lifespan. Expect to replace a thermocouple more often, which results in higher costs.

Learn More About These Dynamic Sensors

At Hi-Watt, we carry the latest Watlow thermistors and reliable thermocouple options. Find out how we can assist you in choosing the best sensor option for your PCB and upgrade your temperature sensors to keep accurate information on hand for your technicians. Contact us today to learn more about the benefits of thermistors and thermocouples and compare leading options to choose the ideal sensor at a great price.

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