Safety related instrument systems for the process industries

Self acting mechanical devices or systems may not be adequate in all cases to prevent hazards on process plants or may not be economically viable. Under these circumstances non-self-acting systems may be used as the primary protection against dangers to personnel. The Health and Safety Executive in 1987 published general guidelines on programmable electronic systems in safety-related applications. The author describes how some of the principles in the H&SE Guidelines may be applied to the systems used in the process industry. The principles applied are those that have been outlined in the EMMUA publication No.160 `safety related instrument systems for the process industries´