A Way of Thinking

What do we mean when we speak of an inherently safer chemical process Inherent has been defined as existing in something as a permanent and inseparable element, quality, or attribute (American College Dictionary, 1967). A chemical manufacturing process is inherently safer if it reduces or eliminates the hazards associated with materials and operations used in the process, and this reduction or elimination is permanent and inseparable. To appreciate this definition fully, it is essential to understand the precise meaning of the word hazard. A hazard is defined as a physical or chemical characteristic that has the potential for causing harm to people, the environment, or property (adapted from CCPS, 1992). The key to this definition is that the hazard is intrinsic to the material, or to its conditions of storage or use. Some specific examples of hazards include  

These hazards cannot be changed—they are basic properties of the materials and the conditions of usage. The inherently safer approach is to reduce the hazard by reducing the quantity of hazardous material or energy, or by completely eliminating the hazardous agent. 

Growl and Louvar (1990) describe a three-step process which most accidents follow  

Inherently safer strategies can impact the accident process at any of the three stages. The most effective strategies will prevent initiation of the accident. Inherently safer design can also reduce the potential for propagating an accident, or provide an early termination of the accident sequence before there are major impacts on people, property, or the environment. 

The approach of imposing barriers between a hazard and potentially impacted people, property, and environment has significant disadvantages  

Process safety is fundamental to the basic practice of chemical engineering thus, the concepts of inherently safer processes should be instilled in chemical engineering students at an early stage. Practicing engineers should be encouraged to adopt the concepts. 

There is work to be done to improve the tools available for the application of inherently safer concepts. Chapter 8 discusses some opportunities for future research. 

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The same G N Lewis who gave us electron dot formulas also suggested a way of think mg about acids and bases that is more general than the Brpnsted-Lowry approach Where Brpnsted and Lowry viewed acids and bases as donors and acceptors of protons (positively charged) Lewis took the opposite view and focused on electron pairs (negatively charged) According to Lewis an acid is an electron pair acceptor and a base is an electron pair donor... 

The Maxwell and Voigt models of the last two sections have been investigated in all sorts of combinations. For our purposes, it is sufficient that they provide us with a way of thinking about relaxation and creep experiments. Probably one of the reasons that the various combinations of springs and dash-pots have been so popular as a way of representing viscoelastic phenomena is the fact that simple and direct comparison is possible between mechanical and electrical networks, as shown in Table 3.3. In this parallel, the compliance of a spring is equivalent to the capacitance of a condenser and the viscosity of a dashpot is equivalent to the resistance of a resistor. The analogy is complete... 

It emphasises the need to research quantitative evaluation risk models and thus to provide for the reader means to define a level of danger, in a rigorous fashion, taking into account in his own way work already carried out in this domain. The model proposed ought to be considered as a route and a clue to a way of thinking and not necessarily as definitive. 

Health economics is the application of the discipline of economics to the topic of health. When viewed in this light, health economics becomes first and foremost a way of thinking based on the principles of scarcity and the need for choice. Although the techniques of economic appraisal (to be discussed later in this chapter) are the principal ways in which the discipline is applied, they are merely the toolkit. The use of these tools without a proper understanding of the principles upon which they are based can be both ineffective and misleading. ... 

CHMP (2005) Guidance on the Choice of Non-Inferiority Margin This much awaited guideline provided some general considerations for the choice of the non-inferiority margin. These considerations were not specific, but nonetheless have given us a way of thinking about the choice (see Section 12.7). 

As a way of thinking, we have to resort to the conceptual knock-down experiments, for examples those outlined in the work by Luisi et al. (2002) and Islas et al. (2004) - a simplification that also corresponds to a movement towards the early cell. 

This book is about making molecules. Or rather it is to help you design your own syntheses by logical and sensible thinking. This is not a matter of guesswork but requires a way of thinking backwards that we call the disconnection approach. 

Marketing as a way of thinking and operating can be summarized in the following concepts ... 

More than anything else, our goal has been to introduce the reader to a way of thinking about problems in photophysics and photochemistry. Although many additional organic photochemical processes could be added to Chapter 7, we have chosen not to do so. Instead, we hope that the reader will be able to apply the understanding of the material that we have chosen to present as he or she approaches the study of additional reactions. 

Quality assurance is not just a process it is a way of thinking. All staff should be well trained and motivated and be working to a common goal the production of a pharmaceutical product of a quality that is safe for the patient. The procedures should not be seen as a chore or burden to make work more difficult, but essential steps in the production of a safe, satisfactory product. Self-inspection and external audit of procedures are important processes in maintaining standards of cleanliness. Even after manufacture and distribution it is vital that the products are used properly, especially multi-use containers that are subject to potential in-use contamination. 

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