When heat or thermal energy is applied to a substance, molecules within that attain kinetic motion. Due to the motion molecules get kinetic energy and temperature is the measure of average molecular kinetic energy within a substance.
Temperature Sensors: For a particular application or process, sensors are individually selected as per the requirement.
1. Nonelectric Temperature Sensors:
- Bimetallic Thermometers
- Filled System Thermometers
2. Electronic Temperature Sensors:
- Resistance Temperature Detectors (RTD)
- Thermocouples
- Thermistors
- Radiation Pyrometers
- Thermal imagery
Installation Considerations
There are two traditional methods of measurement to get process readings for monitoring and control systems. One method is to utilize sensor extension wires to carry the low-level signals (Ω or mV) generated by field-mounted RTD or TC sensors. Another method is to install temperature transmitters at or near the measurement point.
Approvals for Hazardous Areas
Devices installed or mounted in hazardous and explosive environments follow rules or guidelines provided by recognized certification agencies (FM, UL, CSA, and ATEX). These agencies tests equipment and certifies to use of the equipment in a specific area.
Safety Standards
Functional safety is a general concern in industrial applications. To maximize reliability and availability of devices, follow safety standards or guidance provided by organizations like American National Standards Institute/Instrumentation, Systems, and Automation Society, International Electrotechnical Commission, etc.
Instrumentation Basics 