PREFACE

ISA's Independent Learning Modules

This book is an Independent Learning Module (ILM) as developed and published by the Instrument Society of America (ISA). The ILMs are the principal components of a major educational system designed primarily for independent self-study This comprehensive learning system has been custom designed and created for ISA to more fully educate people in the basic theories and technologies associated with applied instrumentation and control.

The ILM System is divided into several distinct sets of Modules on closely related topics; each such set of individually related Modules is called a Series. The ILM System is composed of:

• the ISA Series of Modules on Control Principles and Techniques;
• the ISA Series of Modules on Fundamental Instrumentation;
• the ISA Series of Modules on Unit Process and Unit Operation Control;
• the ISA Series of Modules for Professional Development;
• the ISA Series of Modules for Specific Industries; and
• the ISA Series of Modules on Software-Associated Topics.

The principal components of the Series are the individual ILMs (or Modules) such as this one. They are especially designed for independent self-study; no other text or references are required. The unique format, style, and teaching techniques employed in the ILMs make them a powerful addition to any library.

Most of the original ILMs were envisioned to be the more traditional or fundamental subjects in instrumentation and process control. With the publications planned over the next few years, the ILM Series will become much more involved in emerging technologies.

ISA has increased its commitment to the ILM Series and has set for itself a goal of publishing four ILMs each year. Obviously, this growing Series is part of a foundation for any professional library in instrumentation and control The individual practitioner will find them of value, of course, and they are a necessity in any institutional or corporate library.

There is obvious value in maintaining continuity within your personal set of ILMS; place a standing purchase order with ISA.

Paul W. Murrill
Consulting Editor, ILM Series

Comments about This Volume

My first impression of temperature control was that the dynamics and nonlinearities were too compicated and diverse for a general treatment of value to instrument engineers and technicians. However, after studying the literature, I realized there was a set of generic equations based on first principles that pointed to the problems and opportunities for a wide variety of temperature applications.

At the same time, I realized that the measurement error often exceeded the control error and that the user often was unaware the measurement system error was much larger than the sensor error. Furthermore, based on literature gathered in the last decade, it was evident that the installation effects that increased the system error could be reduced.

The possiblity of a common approach and the need to identify and correct the many sources of measurement system error combined with the importance of temperature control were the primary motivations for writing this book.

Due to the advanced nature of the material presented, the reader is encouraged to read the exercise problems at the end of each section and the solutions in Appendix B. The examples should show the practical utility of the equations and relationships.