For many years, WIKA has been among the leading manufacturers of high-quality industrial temperature measuring instruments. Our experience and know-how in the construction of temperature probes sets us apart.
What is a temperature probe?
The term temperature probe, with electrical thermometers, describes a unit from one or more temperature probe elements and a usage-specific armour, which can consist of, for example, connection head, neck tube, thermowell or a hand grip. The sensor element built into the temperature probe takes the actual measurement and converts the measured temperature into an electrical signal.
With WIKA, temperature probes in industrial temperature measurement are essentially divided between the following groups:
What are temperature probes with thermocouples?
Temperature probes with thermocouples are suitable for the measurement of high temperatures of up to +1,700 °C.
Thermocouples consist of two different metals which are bound together to form the 'thermocouple'. The connection point (hot junction) represents the actual measuring point of the temperature probe, the wire ends are designated as the cold junction. When there is a temperature change at the measuring point of the temperature probe, due to the different electron densities of the metals and the temperature difference, a voltage is generated between the hot and cold junctions. This is approximately proportional to the temperature of the measuring point (Seebeck effect).
The low diameter of the sheathed thermocouple of a temperature probe enables a response time that is faster than is possible with a resistance thermometer.
What are temperature probes with resistance thermometers?
A resistance thermometer has its strengths in the low and medium temperature ranges of -200 … +600 °C. In industry, mainly Pt100 or Pt1000 measuring resistors are used. If the sensor of the temperature probe detects an increase in temperature, then its resistance also increases (positive temperature coefficient). The resistance of a Pt100 resistance thermometer at 0 °C is 100 Ohm, for a Pt1000 resistance thermometer it is 1,000 Ohm.
Basically there are two types of measuring resistors differentiated in temperature probes: Thin-film measuring resistors and wire-wound measuring resistors. The advantages of thin-film measuring resistors are their small overall size and high vibration resistance with the appropriate construction of the temperature probe. Thin-film measuring resistors have come to represent the standard sensor design, provided that they are not ruled out as a result of their temperature range (measuring ranges for accuracy class B temperature probes: Thin-film measuring resistors -50 … +500 °C, wire-wound measuring resistors -200 … +600 °C).
Which surface thermometers can be used for containers and pipelines?
Surface thermometers are suitable for the contactless measurement of temperature on surfaces of containers or pipes. They are designed as resistance thermometers (TR50) or thermocouples (TC50).
The latter allow an exact measurement of extreme temperatures between -40 and +1,200 °C. Both versions are also available with explosion protection.
Surface thermometers are characterized by their easy installation without a protection tube. They are attached to vessels by means of a welded or screwed-on contact block containing the temperature sensor. A variant with a tension band is suitable for mounting on pipelines. Centrically drilled washers or metallic welded-on plates are available as further process connections.
For special ambient conditions, the connection lines of the surface thermometers are supplied with special insulation materials. The cable end is available ready for connection either with mounted plug (optional) or with field housing.
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