Good and bad design

Most factors affecting inherent safety are quite straightforward to estimate since they are e.g. based on the physical and chemical properties of the compounds present. An inherently safe process structure is not possible to define by explicit rules, but one has to rely on standards, recommendations and accident reports. This information is based on the experience gained in the operation practice of different processes (Lees, 1996). For example accident reports, which are made after accidents, give valuable information of the possible weaknesses in the different process solutions. Also extensive databases have been collected from accident reports (Anon, 1996). From this data a database of good and bad designs can be collected. 

Figure 6.6 Comparison between a good and bad design of a boiler tank173...

Other than the obvious considerations of proper facility design, sterilization validation, and sanitization procedures (all of which are discussed elsewhere in this encyclopedia), the focus of attention must be on the personnel and the activities which they must perform. These actions are broadly termed, aseptic technique, and like any other human activity they can be accomplished in a variety of ways. In order to better understand aseptic technique, some general guidance and examples of good and bad technique can be used to delineate what should and should not be permitted. 

Fig. 2. Representations of good and bad joint design. (Reproduced with permission from A J Kinloch, Adhesion and Adhesives Science and Technology, Chapman and Hall, London, 1987)...

Joint design - general C WATSON Flat and cylindrical joints good and bad practice... 

Experimental designs in transfer protocols should consider the use of good and bad batches in a comparison test, where criteria are the release specifications and not the intercompany outcomes of the validation, e.g. mean and variability. The USP [20] recommends that expired, aged, or spiked samples be carefully chosen and evaluated to identify potential problems related to differences in sample preparation equipment and to evaluate the impact of potential aberrant results on marketed products . 

Conditions where three-sided adhesion occurs leads to premature failure by subjecting the elastomer to triaxial stresses. A few examples of good and bad joint design can be seen in Fig. 32. Frequently, it is necessary to prevent adhesion on one or more surfaces in order to eliminate triaxial stress. 

Evolution is comparable to a soap box race. Entropy is the hill. Without the hill there is no race and thus no distinction between good or badly designed cars. Thermodynamics on the other hand describes the rules of the race. ... 

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