TABLE OF CONTENTS "Engineering responsibility should not require the stimulation that comes in the wake of catastrophe."
S. C. Florman
Safety interlock system, safety instrumented system, safety shutdown system, emergency shutdown system, protective instrument system the assorted names go on and on! Different companies within the process industry still use a variety of names for these systems. Within the ISA SP84 committee there was continual discussion (and constant changes) over the term used to describe these systems. The most generic term might be considered safety system, but this means different things to different people. For many chemical engineers, "safety systems" refer to management procedures and practices, not control systems. One very common term has been emergency shutdown system (ESD), but to electrical engineers ESD means electro-static discharge. Many don't want the word emergency in the name at all, as it tends to have a negative connotation. Others don't like the word safety shutdown system for the same reason. Anything appearing in print with the phrase safety draws immediate attention.
When the American Institute of Chemical Engineers, Center for Chemical Process Safety (AIChE CCPS) published "Guidelines for Safe Automation of Chemical Processes" in 1993, the term it used was safety interlock system SIS. Some members of the ISA SP84 committee felt that interlocks were only one subset of many different types of safety control systems.
The ISA committee settled on the term safety instrumented system in order to keep the same acronym...
