| dc.description.abstract | Inherently Safer Design (ISD) concepts have been with us for over two decades since their elaboration by Trevor Kletz [ 1 ]. Interest has really taken off globally since the early nineties after several major mishaps occurred during the eighties (Bhopal, Mexico city, Piper- alfa, Philips Petroleum, to name a few). Academic and industrial research personnel have been actively involved into devising inherently safer ways of production. The regulatory bodies have also shown deep interest since ISD makes the production safer and hence their tasks easier. Research funding has also been forthcoming for new developments as well as for demonstration projects. A natural question that arises is as to how to measure ISD characteristics of a process? Several researchers have worked on this [2 - 4]. Many of the proposed methods are very elegant, yet too involved for easy adoption by the industry which is scared of yet another safety analysis regime. In a recent survey [5], companies desired a rather simple method to measure ISD. Simplification is also an important characteristic of ISD. It is therefore desirable to have a simple ISD measurement procedure. The proposed ISD measurement procedure can be used to differentiate between two or more processes for the same end product. The salient steps are: Consider each of the important parameters affecting the safety (e.g.: temperature, pressure, toxicity, flammability, etc.) and the range of possible values these parameters can have for all the processes under consideration for an end product. Plot these values for each step in each route and compare. No addition of values is being suggested to derive an overall ISD index value since that conceals the effects of different parameters. Further, addition of numbers with different units (C for temperature, atm./bars for pressure, tonnes for inventory, etc.) is inappropriate in scientific sense. These need to be made dimensionless before addition. The proposed approach has a major advantage of expanding consideration in future to incorporate economic, regulatory, pollution control and worker health aspects, as well as factors such as the experience one has or 'the comfort level' one feels with each of the processes underconsideration. Further, this would also guide the designers and decision makers into affecting specific changes in the processes to reduce some of the discomforting features. We demonstrate our simple approach by using the example of 6 routes to making methyl methacrylate as documented by Edwards and Lawrence [2, 6] and show that the decision could well have been different if addition of disparate hazards had not been done. | en |
