Thermocouples consist of two dissimilar metal wires joined at a hot junction; as temperature changes, a millivolt signal is generated. The most common alloy combinations are known as type J and type K thermocouples (ANSI/IEC code). Advantages of thermocouple sensors include low cost, small size, wide temperature ranges and faster response (than RTDs). Many installation styles are available.
Thermocouples have two dissimilar metal wires joined at the hot junction. As temperature changes, a millivolt signal is read at the cold junction. The most common types of temperature thermocouples are type J thermocouples and type K thermocouples. Advantages of thermocouple sensors include: low cost, small size, wider temperature ranges and faster response than RTDs. The disadvantages of using temperature thermocouples include: they are less linear and accurate than RTDs, a matching extension wire is needed, and thermocouples are sensitive to electrical noise.
Resistance Temperature Detectors (RTDs) have a linear increase in resistance as temperature rises. RTDs come in 2-,3- or 4-wire versions. A 2-wire RTD signal is affected by the distance to the controller. 3-wire or 4-wire RTDs can compensate for line losses.
AutomationDirect offers a variety of industrial thermocouple temperature sensors:
For more thermocouple products, see the Temperature Sensors & Transmitters Category:
Thermocouple probes with IP66 NEMA 4X connection heads offer measuring ranges from 32 to 2100 degrees F.
Spring-loaded probes ensure tip contact in thermowells for highly accurate temperature readings with measuring ranges from 32 to 1700 degrees F.
Heat Trace probes measure the surface temperature of process pipes to detect freeze-up or help maintain a viscosity level to ensure proper flow of the medium inside.
Thermocouple probes with hex nipples allow easy probe replacement and connection to a junction box.
Spring-loaded thermocouple probes with hex nipples ensure tip contact in thermowells and allow easy probe replacement and connection to a junction box.
Probes with an attached plug allow for quick and easy plug-in connections and provide measurements down to -328 degrees F
Probes with heavy-duty 6 ft. lead wire transitions allow easy connection to thermocouple extension wire and feature a wide measuring range from -328 to 2100 degrees F.
Flange mount probes are ideal for use with ovens, freezers, ducts, or any application where through-the-wall temperature sensing is required.
Probes with cuttable lengths provide utmost flexibility and can be trimmed to the required length of a specific application.
Melt-bolt probes measure the melt temperature of plastic as it moves down the barrel of an extruder or injection molding machine.
Immersion thermocouples are designed to be inserted into the medium being measured. Used throughout all industries but ideal for the plastics processing industry.
Bolt-on thermocouples feature a ring terminal or washer and are bolt or screw mounted for surface temperature measurements.
Threaded bolt sensors are thread-mounted and feature a 1/4-28 UNF threaded stainless steel rotating bolt for easy installation .
Wall-mount room temperature sensors (indoor ambient air temperature sensor) are appropriate for indoor use in offices, warehouses, manufacturing plant floor space, and walk-in freezers
Sensors with a spade tip have a thermocouple sandwiched between two thin shims of stainless steel or sealed in epoxy between two layers of polyimide tape. Tip can be formed and secured to the outside of various size tubes, pipes, or nozzles.
Magnetic-mount sensors measure the surface temperature of ferrous and are affixed with a convenient and non-destructive magnetic attachment.