Process analysers components

Naturally, the sampling of solids, liquids and gases requires different approaches. Often, noncontact spectroscopic probes are used for powders, tablets and thick slurries. Gases can often be sampled in the same way as liquids but may require some preconcentration prior to analysis, especially if levels of the analyte being examined are low. An example of a commercially available system for sampling gases is available from ABB. It is called the DRS2170 Dynamic Reflux Sampler and is used to couple with GC instruments, photometers and other process analysers. It conditions samples in situ. The condensable components are removed and are used to support particulate removal. The unit... 

Over the period of evolution of combinatorial and automated synthetic procedures we have moved from the analysis of combinatorial libraries (typically 100-500 components) to the semiquantitative analysis of single products synthesized simultaneously in a parallel process. Analyses of libraries previously involved lengthy HPLC or HPLC-MS assays as the aim was then to prove the existence, or otherwise, of all components of the library under exanunation (Fig. 2). Such assays required in excess of 30 min to complete with lengthy manual processing of the resulting data. 

Fig. 17.2 Typical arrangement of components of a dual beam NDIR process analyser.

Economically, cost-effective performance of valve maintenance means performing and bundling of all individual activities under the umbrella of an experienced service provider which act as a main contractor. The great advantage of such a contract for the customer is to order the complete maintenance service on a fixed price which is lower as the total cost obtained from a large number of individual services. Competent and reliable subcontractors which are familiar with special features of components are involved to ensure good quality of work. Under such conditions the mutual cooperation can preserve the maintenance competence and know-how to ensure the safety and availability as long as the nuclear power plant is in service. Effective improvements based on process analyses can also be implemented. 

The procedure for analysis will best be performed in a stepwise manner. In the screening process, candidate components for PIE sources should be identified. This screening process should be followed with due caution, and in case of doubt the component in question should not be excluded but rather put on the list of potential hazards that have to be analysed in more detail. Probabilistic safety assessment may be useful for this purpose. 

Components of the governing equations of the process can be decoupled to develop a solution scheme for a three-dimensional problem by combining one- and two-dimensional analyses. 

The critical characteristic on each component was analysed, calculated from the analysis and the value obtained was plotted against the process capability indices, Cpk and Cp, for the characteristic in question. See Appendix V for descriptions of the 21 components analysed, including the values of Cp and Cp from the SPC data supplied. Note that some components studied have a zero process capability index. This is a default value given if the process capability index calculated from the SPC data had a mean outside either one of the tolerance limits, which was the case for some of the components submitted. Although it is recognized that negative process capability indices are used for the aim of process improvement, they have little use in the analyses here. A correlation between positive values (or values which are at least within the tolerance limits) will yield a more deterministic relationship between design capability and estimated process capability. 

Note that the squared relationship which was initially used to model the degree of difficulty in obtaining more capable tolerances for a given manufacturing route and product design is being returned by the power law. Similarly, a relationship between the process capability index Cp and q for the components analysed is shown in... 

Tolerance stack analysis - Tolerances on components that are assembled together to achieve an overall design tolerance across an assembly can be individually analysed, their potential variability predicted and their combined effect on the overall conformance determined. The analysis can be used to optimize the design through the explorations of alternative tolerances, processes and materials with the goal of minimizing the costs of non-conformance. This topic is discussed in depth in Chapter 3. 

The link with FMEA brings into play the additional dimension of potential variability into the assessment of the failure modes and the effects on the customer. The Conformability Matrix also highlights those bought-in components and/or assemblies that have been analysed and found to have conformance problems and require further communication with the supplier. This will ultimately improve the supplier development process by highlighting problems up front. 

Figure 3.3 Empirical relationship between Cp and Cp showing degree of process shift expected for the components analysed...

This PSA construction process provides results but tends to obscure the interpretation of what led to these results. Sensitivity analyses are basically studies of the effect on risk due to small or large changes in system/component reliability or operability (see Section 2.8). 

---