Mastering Industrial Temperature Measurement: Your Complete FAQ Guide
30 September 2026
Temperature is one of the most commonly measured process variables across industry. From monitoring boilers and steam systems to controlling food and beverage processes, chemical production, pharmaceuticals and oil and gas applications, accurate temperature measurement is essential for process control, product quality, energy efficiency and equipment protection.
But with so many different sensors, thermometers, transmitters and installation options available, selecting the right temperature measurement solution isn’t always straightforward.
In this guide, we answer some of the most frequently asked questions about industrial temperature measurement instrumentation and explain what to consider when choosing the right solution for your process.
What is temperature measurement instrumentation?
Temperature measurement instrumentation is used to measure, monitor and control the temperature of a process, product, gas, liquid, solid or piece of equipment.
Depending on the application, this could include:
- Resistance temperature detectors (RTDs)
- Thermocouples
- Infrared temperature sensors and pyrometers
- Bimetal thermometers
- Digital temperature transmitters
- Temperature switches
- Thermowells
- Clamp-on temperature sensors
- Remote or wireless temperature sensors
The appropriate technology depends on factors such as the required temperature range, accuracy, process conditions, installation requirements and whether the measurement needs to be continuous or occasional.
Process Instrument Solutions provides temperature measurement solutions for gases, liquids and solids, with instrumentation suitable for a wide range of industrial applications.
What are the main types of temperature sensors?
There are several different technologies used for industrial temperature measurement.
RTDs
Resistance Temperature Detectors (RTDs) measure temperature by monitoring the change in electrical resistance of a sensing element.
RTDs are widely used where good accuracy and stability are required, particularly within relatively moderate temperature ranges.
Thermocouples
Thermocouples use two different metals joined together to generate a voltage that changes with temperature.
They are available in different types, including Type J, K, N, E, R and S, with each type offering different temperature ranges and characteristics.
Thermocouples are particularly useful for higher-temperature applications and processes where a robust sensor is required.
Check out our helpful Thermocouples Colour Chart for more information.
Infrared temperature sensors
Infrared sensors measure temperature without needing to make physical contact with the surface being measured.
This makes them useful for applications where contact measurement is difficult, impractical or could interfere with the process.
Process Instrument Solutions offers infrared temperature sensors and pyrometers for applications including temperature measurement of solids and other challenging processes.
Mechanical thermometers
Bimetal and gas expansion thermometers provide a straightforward way of displaying temperature locally.
These can be useful where a simple visual indication is required without necessarily requiring a digital control signal.
What is the difference between an RTD and a thermocouple?
Both RTDs and thermocouples are commonly used for industrial temperature measurement, but they operate differently.
RTDs measure temperature based on electrical resistance, while thermocouples generate a voltage related to the temperature difference between the measurement junction and reference junction.
However, there is no universal “better” option. The correct choice depends on the process.
How accurate does my temperature measurement need to be?
The required accuracy depends on what you’re trying to achieve.
For example, a small temperature error might have little consequence for general equipment monitoring but could be significant in a tightly controlled manufacturing process.
When determining the required accuracy, consider:
- The acceptable process tolerance
- Product quality requirements
- Safety requirements
- Control system requirements
- Energy efficiency targets
- Regulatory or industry requirements
- The accuracy of the complete measurement chain
It’s also important to remember that sensor accuracy is only one part of overall measurement accuracy.
The installation, transmitter, cabling, calibration, process conditions and location of the sensor can all influence the final measurement.
Why is sensor location important?
A temperature sensor only measures the temperature at the point where it is installed.
If the sensor is positioned incorrectly, it may not represent the actual process temperature.
For example, a sensor installed too close to a pipe wall may be influenced by the surrounding environment rather than accurately measuring the process medium.
When selecting an installation point, consider:
- Process flow
- Mixing and temperature gradients
- Pipe diameter
- Sensor insertion depth
- Heat transfer
- Ambient conditions
- Potential vibration
- Accessibility for maintenance and calibration
Good sensor positioning can be just as important as choosing the right sensor technology.
What is a thermowell and why is it used?
A thermowell is a protective tube installed around a temperature sensor.
It allows the temperature sensor to be protected from the process while also allowing the sensor to be removed for inspection, maintenance or replacement without necessarily interrupting the process.
Thermowells can be particularly useful in applications involving:
- High pressures
- High temperatures
- Corrosive media
- High flow velocities
- Abrasive processes
However, thermowell design needs to take the process conditions into account. Incorrect selection can affect response time and measurement performance, so factors such as material, insertion length, process pressure, temperature and flow should be considered.
Process Instrument Solutions supplies temperature sensors and thermowells for continuous process measurement applications.
What does a temperature transmitter do?
A temperature transmitter converts the signal from a temperature sensor into a standardised output that can be transmitted to a control system, PLC, DCS or other monitoring equipment.
For example, a transmitter can take the signal from an RTD and convert it into a 4–20 mA output.
Modern transmitters may also support communication protocols such as HART, allowing additional information and configuration capabilities to be accessed.
Process Instrument Solutions supplies temperature transmitters including Siemens and Labom solutions.
What is the difference between a temperature sensor and a temperature transmitter?
The terms are sometimes used interchangeably, but they perform different functions.
A temperature sensor detects the temperature.
A temperature transmitter processes the sensor’s signal and converts it into an output suitable for a control or monitoring system.
In a typical installation:
Process → Temperature Sensor → Transmitter → Control System → Operator
Some instruments combine these functions into a single assembly.
What is a 4–20 mA temperature signal?
4–20 mA is a common analogue signal used in industrial automation.
The temperature measurement is represented by a current between 4 mA and 20 mA.
For example, if a transmitter is configured for a range of 0–100°C:
- 4 mA = 0°C
- 12 mA = 50°C
- 20 mA = 100°C
The exact measurement range can be configured according to the application and transmitter capabilities. Siemens temperature instrumentation, for example, allows the lower and upper range values to be assigned to the current output.
Why is temperature calibration important?
Even high-quality temperature instruments can experience measurement drift over time.
Calibration compares the instrument’s measurement against a known reference to determine whether it is operating within the required accuracy.
Regular calibration can help:
- Maintain measurement accuracy
- Identify sensor drift
- Support quality assurance
- Prevent incorrect process decisions
- Improve confidence in process data
- Identify potential instrumentation problems before they affect production
Calibration intervals should be determined based on the application, instrument performance, criticality of the measurement and your site’s procedures.
Process Instrument Solutions also provides instrumentation services including calibration, installation, commissioning and troubleshooting.
What causes inaccurate temperature readings?
There are many potential causes of inaccurate temperature measurements.
Common issues include:
Incorrect sensor selection
The sensor may not be suitable for the process temperature, pressure, medium or environment.
Poor installation
Incorrect insertion depth or sensor positioning can result in a measurement that does not accurately represent the process.
Sensor ageing or drift
Sensors can change characteristics over time, particularly when exposed to demanding process conditions.
Electrical interference
Signal cables and electrical installation can affect the measurement signal.
Damaged sensors
Mechanical damage, corrosion or excessive temperature exposure can affect sensor performance.
Incorrect transmitter configuration
An incorrectly configured measurement range, sensor type or output can result in incorrect readings.
Troubleshooting should therefore consider the complete measurement chain, rather than simply replacing the sensor.
Can temperature be measured without contact?
Yes.
Non-contact temperature measurement is commonly achieved using infrared technology.
Infrared sensors detect the infrared energy emitted by a surface and use it to determine temperature.
This can be advantageous when:
- The process is moving
- The material is inaccessible
- Contact could contaminate the product
- The material is extremely hot
- The sensor could be damaged by the process
- The surface is difficult to access
However, infrared measurement has its own considerations, including surface characteristics, measurement distance, field of view and environmental conditions.
What temperature instrumentation is suitable for hazardous areas?
Where temperature measurement is required in a potentially explosive atmosphere, the instrumentation must be suitable for the hazardous-area classification and application.
This may require appropriately certified equipment, such as ATEX-certified or intrinsically safe temperature instrumentation.
The correct certification depends on the hazardous area, gas or dust classification and installation requirements.
Our temperature portfolio includes instrumentation with certifications such as ATEX and other industry approvals, depending on the product.
For hazardous-area applications, the complete installation should be assessed to ensure that the selected instrumentation and associated equipment meet the relevant requirements.
Can temperature sensors be used in food and beverage applications?
Yes, temperature measurement is an important part of many food and beverage processes.
Applications can include:
- Brewing
- Dairy processing
- CIP systems
- Pasteurisation
- Product storage
- Water and steam systems
- Refrigeration
- Process heating and cooling
For hygienic applications, sensor construction, materials, connections, cleanability and installation are important considerations.
The sensor must be appropriate for the process and the required hygiene standards.
What should I consider when selecting a temperature instrument?
Rather than selecting a temperature sensor based solely on measurement range or price, consider the complete application.
Ask:
- What is the process medium?
Gas, liquid or solid? - What temperature range needs to be measured?
- What level of accuracy is required?
- Is continuous or local measurement required?
- Does the sensor need to be contact or non-contact?
- What are the process pressure and flow conditions?
- Is the process corrosive or abrasive?
- Is a thermowell required?
- What output does the control system require?
- Is hazardous-area certification required?
- How frequently will the instrument need to be calibrated or maintained?
- How accessible is the sensor for inspection and replacement?
Taking these factors into account at the specification stage can help prevent measurement problems later.
When should I use a temperature transmitter?
A transmitter is particularly useful when the temperature measurement needs to be integrated into a wider control or monitoring system.
For example, a transmitter can allow temperature information to be sent to a PLC or DCS for:
- Process control
- Alarms
- Trending
- Data logging
- Remote monitoring
- Energy management
- Predictive maintenance
Modern temperature transmitters can also provide additional diagnostic and configuration information, helping operators and engineers understand the condition of the measurement system.
How can temperature measurement improve process efficiency?
Temperature measurement isn’t simply about knowing how hot or cold something is.
Accurate temperature data can support better process decisions.
For example, it can help operators:
- Optimise heating and cooling systems
- Reduce energy consumption
- Maintain consistent product quality
- Detect abnormal operating conditions
- Protect equipment
- Improve process control
- Identify potential maintenance issues
- Reduce waste and production losses
In energy-intensive processes, even relatively small improvements in temperature control can contribute to improved overall efficiency.
What temperature measurement solution do I need?
There isn’t one temperature instrument that is suitable for every application.
The best solution depends on the process, measurement requirements and operating environment.
At Process Instrument Solutions, our temperature measurement portfolio includes temperature sensors, RTDs, thermocouples, transmitters, thermometers, temperature switches, infrared sensors and thermowells, with solutions for gases, liquids and solids.
Our team can also support customers beyond product supply, including instrumentation design, installation, commissioning, calibration and servicing.
Need help selecting the right temperature instrument?
Choosing the right temperature measurement technology starts with understanding the application.
If you’re experiencing unreliable temperature readings, replacing obsolete instrumentation or specifying temperature measurement for a new process, our team can help identify a suitable solution.
Get in touch with Process Instrument Solutions to discuss your temperature measurement requirements.