Intrinsic safety comparison

The basic idea is to simplify techniques which have proved successful in the field of intrinsic safety in such a way that they will comply with the risks of zone 2. In comparison with intrinsic safety - i -, the fault assessment can be dropped and the reference curves (Figs 6.162-6.167) are applied with a safety factor of 1.0 (i.e. voltage and current values do not have to be reduced additionally in comparison with those given in the reference curves). Other requirements relevant for intrinsic safety - i - are still applicable, e.g. the two-thirds rating of components on which the type of protection depends. 

The intrinsic safety effect of this equipment was estimated through study of comparisons of actual crashes and through study of simulated crashes in laboratories. 

Many causality algorithms and categorisation systems have been proposed but none has gained universal acceptance, and the value of assessing this for each individual report of a suspected ADR now seems to be doubtful. It is certainly much more efficient to reserve such assessment for a series of cases which might represent a new and/or important safety issue. Systematic assessment of causality in individual cases occurring in clinical trials is intrinsically a weaker approach to assessing causality than comparison of numerical cormts. 

Berry, T. D., Geller, E. S., Calef, R. S., and Calef, R. A., Moderating effects of social assistance on verbal interventions to promote safety belt-use an analysis of weak plys. Environ. Behav., 24,653,1992. Boyce, T. E. and Geller, E. S., Attempts to increase prosocial behavior a comparison of reinforcement and intrinsic motivation theory. Environ. Behav. in press. 

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