Qualitative techniques

Chisel. Chisel testing is a quick, qualitative technique that is widely used to determine the soundness of explosion-welded metal interfaces. A chisel is driven into and along the weld interface, and the abiUty of the interface to resist the separating force of the chisel provides an excellent quaUtative measure of weld ductihty and strength. 

Hazard and Operability Study (HAZOP) A systematic qualitative technique to identify process hazards and potential operating problems using a series of guide words to study process deviations. 

Process Hazard Analysis (PHA) An organized effort to identify and evaluate hazards associated with chemical processes and operations to enable their control. This review normally involves the use of qualitative techniques to identify and assess the significance of hazards. Conclusions and appropriate rec-... 

The purpose of this chapter is to show that improvements in safety, quality, and productivity are possible by applying some of the ideas and techniques described in this book. The fact that error reduction approaches have not yet been widely adopted in the CPI, together with questions of confidentiality, has meant that it has not been possible to provide examples of all the techniques described in the book. However, the examples provided in this chapter illustrate some of the most generally useful qualitative techniques. Case studies of quantitative techniques are provided separately in the quantification section (Chapter 5). The first two case studies illustrate the use of incident analysis techniques (Chapter 6). 

The Chemical Process Industry (CPI) uses various quantitative and qualitative techniques to assess the reliability and risk of process equipment, process systems, and chemical manufacturing operations. These techniques identify the interactions of equipment, systems, and persons that have potentially undesirable consequences. In the case of reliability analyses, the undesirable consequences (e.g., plant shutdown, excessive downtime, or production of off-specification product) are those incidents which reduce system profitability through loss of production and increased maintenance costs. In the case of risk analyses, the primary concerns are human injuries, environmental impacts, and system damage caused by occurrence of fires, explosions, toxic material releases, and related hazards. Quantification of risk in terms of the severity of the consequences and the likelihood of occurrence provides the manager of the system with an important decisionmaking tool. By using the results of a quantitative risk analysis, we are better able to answer such questions as, Which of several candidate systems poses the least risk Are risk reduction modifications necessary and What modifications would be most effective in reducing risk ... 

While tlris qualitative technique is most commonly applied to operating process plants, it is also applicable to pilot plants, laboratories, storage facilities, or support functions. This comprehensive review is intended to complement other safety efforts and routine visual inspections. It should be treated as a cooperative effort to improve the overall safety and performance of the plant rather than as a dreaded intciference vvitli normal operations. Cooperation is essential. People tne likely to become defensive unless considerable effort is made to present the review as a benefit to each participant. 

Two-dimensional separations in planar chromatography are rather trivial to perform. All unidimensional multiple development techniques employ successive repeated development of the layer in the same direction, with removal of the mobile phase between developments. The main variants are multiple chromatography and incremental multiple development. The basis for automated multiple development (AMD) is the automation of unidimensional, incremental, multiple development with a reverse solvent strength gradient [998]. 2D TLC finds limited use, and is mainly a qualitative technique. 

A wide range of analytical techniques are today available for identifying and characterizing materials (Hancock 2000). Some, known as qualitative techniques, are designed to provide information only on the nature of the components of materials, that is, which components, elements, and/or compounds, make up a material (Masterton and Slowinski 1986). Most often, however, it is also essential to disclose precisely how much of each particular component there is in a material, and thus to reveal its exact composition. Such information is derived using quantitative techniques (Harris 2002 Jeffery et al. 1989). 

Mattson and Mark [55,56] reported some criticism of Kawahara s technique. They claim that evaporation of the solvent chloroform by infrared heating removes volatiles and causes large changes in the ratios. An oil sample was shown to suffer such alteration by the infrared during repeated analysis. The absorption of all bands decreased nonuniformly between 20 and 100% over a period of 30 min. They propose the application of internal reflection spectrometry as a rapid, direct qualitative technique requiring no sample pretreatment. 

This is considered to be largely a qualitative technique. Difficulties that arise in obtaining reproducible quantitative data are similar to those encountered in thin-layer chromatography. In addition, adsorption characteristics of dyes on macromolecules are so variable that only semiquantitative comparisons can be made. These are, however, still very useful... 

Potentially applicable to a wide range of organic materials. Most use has been made in the analysis of polymers and oils. Essentially a qualitative technique with poor precision for quantitative measurements. 

Hazard evaluation— The analysis of hazardous situations associated with a process or activity, using qualitative techniques to identify weaknesses in design and operation. 

Definition 7 An expert system is a computer program that manipulates large amounts of symbolic knowledge using qualitative techniques, to solve problems that can otherwise be solved only by expert human problem solvers. Expert systems capture the human problem solvers expertise in the form of domain-specific knowledge and domain-independent problem-solving strategies. 

Definition 2 Knowledge-based systems are computer programs that encode symbolic knowledge about domains and tasks, and solve problems by manipulating this knowledge using qualitative techniques. 

Acrylic Crosslinkers. Butanediol diacrylate (IV) (BDDA) is a popular crosslinker used in the preparation of many polymers used for inks, paints, and plastics. Low-levels of impurities can adversely affect product properties. As previously discussed, K+IDS provides a powerful qualitative technique, but yields poor quantitative data when analyzing volatile chemicals. BDDA is amenable to analysis by GC, unfortunately any higher-molecular-weight adducts exceed the volatility range amenable to GC. Moreover, BDDA is not chromophoric thereby HPLC characterization is also difficult. 

Fig. 10.11 Representation of hybrid approach in which Kohonen maps, neural nets, multiple component analysis, and pattern recognition are combined to create a complex data evaluation cascade. Within this cascade supervised (quantitative) and unsupervised (qualitative) techniques are combined (Hierlemann et al., 1996)...

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