Safety engineering strategy

FIGURE 20.7 Comparison of measured and modeled HRR in room/corner test with wood lining materials. (Adapted from Carlsson, J., Computational strategies in flame-spread modelling involving wooden surfaces—An evaluation study, Lund University Department of Fire Safety Engineering, Lund, Sweden, Report 1028, 2003.)... 

In his book, Charles Perrow discusses the challenge of risks related to complex systems. An adverse event often results from a combination of little events. For some small events there is redundancy. There is an alternative so an event does not lead to a more serious consequence. In safety engineering there is a need to find redundancy in systems. Chapter 9 discussed redundancy as a preventive strategy. It introduced single-point failures, a lack of redundancy. 

Clearly novelty has an impact on safety case confidence. An argument approach that hasn t been seen before is more difficult to assess than an approach that has been successfully used. The historical approach to safety engineering has always included an element of fly and fix , whereby faults are removed once the system has been operated and accidents or incidents have occurred. The necessity for this type of approach (which is not ideal) is due to a lack of ability to assess novelty. Novelty occurs within safety cases due to the use of new technologies and new argument strategies. 

ACP.Sl. There is sufficient confidence that mitigating credible hazards will demonstrate that the insulin pump is adequately safe for routine use. Arguing over hazards is a widely accepted strategy in safety engineering, and this fragment of the confidence case is simple to construct. 

A general strategy for safety engineering appears in Figure 6.2. This strategy provides a sequence of choices in dealing with designs for safety and health. 

Although the primary role of safety engineering is to prevent unsafe conditions, it must reflect the hundreds of design standards for safety (enforcement) and reduce the opportunity for errors and unsafe acts by users through designs that reflect human limitations and capabilities 84 The Hazard Control Priority Tree provides an orderly strategy for selecting controls for hazards 85... 

Frank M.V., (1995) Choosing among Safety Improvement Strategies a Discussion with Example of Risk Assessment and Multi-Criteria Decision Approaches for NASA , Reliability Engineering Systems Safety, Vol. 49, No. 3, pp. 311-324. 

G. L. Elamm and R. G. Schwartz, Issues and Strategies in Risk Decision Making, International Process Safety Management Conference and Workshop, September 22-24, 1993, San Francisco, CA, 351-371, American Institute of Chemical Engineers, New York, NY, 1993. 

N.B. Hanes, and A.M. Rossignol, Comprehensive Occupational Safety and Health Engineering Aeadcmic Program Development Strategy, U.S. Department of Health and Human Services, Springfield, VA Nat. Tech. Info. PB 86-226453, 1984. 

The word safety used to mean the older strategy of accident prevention through the use of hard hats, safety shoes, and a variety of rules and regulations. The main emphasis was on worker safety. Much more recently, safety has been replaced by loss prevention. This term includes hazard identification, technical evaluation, and the design of new engineering features to prevent loss. The subj ect of this text is loss prevention, but for convenience, the words safety and loss prevention will be used synonymously throughout. 

These points are explained in detail in this chapter. In a first section, the general aspects of reaction engineering for batch reactors are briefly presented. The mass and heat balances are analysed and it is shown that a reliable temperature control is central to the safety of batch reactors. The different strategies of temperature control and their consequences on reactor safety are explained in the following sections. For each strategy, the design criteria and the safety assessment procedure are introduced. The chapter is closed by recommendations for the design of thermally safe batch reactions. 

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