Temperature Measurement and Control Equipment

Temperature Sensors – Thermocouples

Temperature sensors and thermocouples are sensing devices that convert the measured temperature into an electrical value that can be passed to a controller, a PLC or building automation. The category covers head-mounted and cable PT100 resistance thermometers, type J thermocouples and temperature transmitters with 4–20 mA output.

A PT100 element has a resistance of 100 Ω at 0 °C that increases as temperature rises; a thermocouple produces a small temperature-dependent voltage at the junction of two different metals. IEC 60751 resistance thermometers are made in classes B, A and AA, with 3, 6 or 8 mm measuring inserts and lengths of 100–1100 mm, as single or dual elements.

Pt100 / Pt1000resistance element

Class AA–BIEC 60751

−196…+600 °Csensor range

4–20 mAhead-mounted transmitter

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Main Applications

Passing boiler water temperature to the controller in boiler and burner automation
Flow and return measurement in building automation and HVAC systems
Recorded temperature monitoring in food, chemical and pharmaceutical processes
Measurement with thermocouples in furnace and heat treatment applications
Sending 4–20 mA signals to PLC and SCADA systems

Technical Data

Measuring element	Pt100 or Pt1000 resistance; type J thermocouple
Number of elements	Single or dual (2 × Pt100)
Connection method	2, 3 or 4-wire
Accuracy classes	B, A, AA (IEC 60751); A and AA not with 2-wire connection
Class B tolerance	±(0.30 + 0.0050 \|t\|) °C
Sensor range	−196…+600 °C (depending on element and class)
Measuring insert diameter	3, 6 or 8 mm
Insertion + neck length	100–1100 mm
Head protection	IP65 (IP40 without thermowell)
Ambient temperature	−40…+80 °C
Response time (Ø6 insert, water)	t0.5 = 3.8 s · t0.9 = 8.6 s
Transmitter output	Head-mounted 4–20 mA; HART option

Material Options

Part	Head-mounted PT100	Cable PT100	Type J thermocouple
Sensing element	Pt100 / Pt1000, single or dual	Pt100	Fe-CuNi thermocouple pair
Sheath	1.4571 or 316L measuring insert	Depending on model	Depending on model
Connection head	Aluminium, plastic or stainless (EN 50446)	No head; cable outlet	Depending on model
Neck tube	1.4571, standard 150 mm	Not applicable	Depending on model
Process connection	Threaded connection to thermowell	Depending on model	Depending on model

Note: Technical data are from the manufacturer data sheet of the head-mounted resistance thermometer; sheath material, cable type and temperature limit of cable sensors and type J thermocouples vary by model. For devices that process the sensor signal, see the process control devices page.

Advantages

Remote monitoring

The sensor signal is carried to a panel, PLC or SCADA system.
Measured values can be recorded.

Accuracy classes

Select between B, A and AA to suit the application.
Class AA tolerance is ±(0.10 + 0.0017 |t|) °C.

Dual element

On 2 × PT100 types one element is used for control, the other for recording or as a spare.
Two separate devices are fed from one measuring point.

Fast response

A Ø3 mm insert responds in water with t0.5 = 2.8 s.
Thin inserts are an advantage in fast-changing processes.

Construction and Design Features

Pt100 / Pt1000 or thermocouple measuring element
Measuring insert with 1.4571 or 316L sheath
EN 50446 aluminium, plastic or stainless connection head
4–20 mA transmitter that fits inside the head
1.4571 neck tube and thermowell connection

Send us the element type, class, number of wires, length and head or cable preference via the Request a Quote form and we will prepare the sensor together with its thermowell.

How to Choose?

Check the input typeChoose the element according to the input accepted by the device (PT100, PT1000, type J or K).
Choose the number of wiresUse 3 or 4-wire connection for long cables or when class A or AA is required.
Calculate the lengthThe measuring insert is sized to the thermowell, and the thermowell to the pipe diameter.
Head or cablePrefer head-mounted types for field installation and cable types in tight spaces inside equipment.
Define the signal needFor long distances and PLC connection, choose a type with a head-mounted 4–20 mA transmitter.