Preface

Temperature is one of the most frequently measured physical quantities in industry. The accuracy and consistency of that measurement can directly influence product quality, process efficiency, raw material usage, and equipment life. Whether in process control, safety interlocks, energy optimization, or predictive maintenance, reliable temperature data underpins good decision-making.

Across all sectors, the demand for more accurate and repeatable temperature measurements is driving closer attention to the technologies and methods used. While many users are content to rely on pre-configured systems, a deeper understanding of how temperature sensing works can unlock real performance gains.

This guide offers a clear and practical introduction to the two most widely used technologies in industrial temperature measurement: thermocouples and resistance thermometers (RTDs). Together, these sensors meet the majority of temperature sensing needs — from cryogenic conditions below -200°C to extreme industrial environments exceeding +3,000°C.

Thermocouples are typically chosen for their ruggedness, wide range, and versatility. RTDs, while covering a narrower temperature span, are valued for their accuracy and long-term stability. Both technologies convert temperature into electrical signals, allowing them to integrate easily with modern control systems for display, logging, transmission, and diagnostics.

Advancements in materials and electronics continue to push the capabilities of both sensor types — from enhanced sheathing options to the rise of smart transmitters and self-diagnosing sensors.

This revised online edition maintains the technical clarity and depth the original printed guide was known for. It covers everything from sensor theory and international standards to material selection, installation practices, and practical tips for real-world applications. It is designed to be read from start to finish or referenced section-by-section, with links and cross-references throughout.

Whether you're specifying a new system or simply want to understand the tools you're working with, this guide remains an essential resource for engineers, technicians, and anyone involved in temperature measurement.