Temperature is one of the most critical parameters in industrial processes. Incorrect temperature measurement can lead to reduced product quality, energy inefficiency, and even serious safety risks. For this reason, temperature measurement systems and sensors are integral parts of process control.
PRINCIPLES OF TEMPERATURE MEASUREMENT
Temperature measurement is used to determine the energy state of fluids or solids. The fundamental formula is:
Q = m · c · ΔT
Where Q is heat energy (J), m is mass (kg), c is specific heat capacity (J/kgK), and ΔT is the temperature change (K).
Heat transfer mechanisms — conduction, convection, and radiation — must be considered when positioning temperature sensors.
TYPES OF TEMPERATURE SENSORS
• Thermocouples: Based on the Seebeck effect, suitable for a wide temperature range.
• RTDs (Resistance Temperature Detectors): Measure resistance changes, offering high accuracy.
• Thermistors: Provide very precise readings over a narrower temperature range.
• Infrared (IR) Sensors: Enable non-contact temperature measurement.
• Bimetal Thermometers: Simple mechanical devices operating on thermal expansion.
FACTORS AFFECTING MEASUREMENT ACCURACY
• Calibration of the sensor
• Immersion depth and sensor positioning
• Environmental conditions such as humidity, vibration, and electromagnetic interference
• Quality of insulation materials
If these factors are not considered, measurement errors may increase significantly.
STANDARDS AND CALIBRATION
• IEC 60751: International standard for RTD sensors.
• ASTM E230: Defines thermocouple classes and tolerances.
• ISO 17025: Accreditation standard for calibration laboratories.
APPLICATION AREAS
• Turbine and boiler temperature monitoring in power plants
• Reactor temperature measurement in chemical industries
• Pasteurization and cooking processes in the food industry
• Ambient temperature control in HVAC systems
CONCLUSION
Selecting the right sensor, performing regular calibration, and ensuring proper installation make temperature measurement systems indispensable for safety, efficiency, and product quality in industrial operations.