Measurement, troubleshooting problems

When a troubleshooting problem has been identified, the first measures are often to apply a patch to the process. Patches are temporary measures that may be instituted to raise the quality of a product or intermediate. A patch may involve a recrystallization to eliminate or reduce the levels of impurities generated in the isolated material it may involve recrystallizing the intermediate producing this material. Often measures to develop patches are begun immediately after a problem has been identified, particularly when the problem arises in a manufacturing operation. 

There are several lessons to be learned from this process troubleshooting problem. As discussed earlier in this chapter, it is inportant not to focus on one possible solution to the exclusion of others. It is inportant to consider as many alternatives as possible. Several possible causes were presented here for the observed process upsets. Wthout detailed measurements and/or simulations, which take more time to perform, the other possibilities could not be ruled out. They would cause the same qualitative trends, but different quantitative values for the upset parameters. 

Measurement Selection The identification of which measurements to make is an often overlooked aspect of plant-performance analysis. The end use of the data interpretation must be understood (i.e., the purpose for which the data, the parameters, or the resultant model will be used). For example, building a mathematical model of the process to explore other regions of operation is an end use. Another is to use the data to troubleshoot an operating problem. The level of data accuracy, the amount of data, and the sophistication of the interpretation depends upon the accuracy with which the result of the analysis needs to oe known. Daily measurements to a great extent and special plant measurements to a lesser extent are rarelv planned with the end use in mind. The result is typically too little data of too low accuracy or an inordinate amount with the resultant misuse in resources. 

The activities under interpretation are divided into four categories. Troubleshooting is a procedure to identify and solve a problem in the unit. Hypothesized causes for the observed problems are developed and then tested with appropriate measurements or identification of changes in operating conditions. 

Troubleshooting is described by suggesting possible causes of the more common problems and discussing corrective measures. 

Here is a problems checklist for troubleshooting measurement Table 1 Common Measurement Problems ... 

Common problems for pH measurements include potential or temperature drift, breakage of the electrode when it is handled, sluggish pH response, low value for the slope, and so on. Most pH meter manufacturers have provided quite intensive troubleshooting instructions in their instrument manual. Table 15.2 is a summary of some common solutions. 

Anticipated problems and counter measures for the listed protocols have been included in individual steps of the basic protocols. In addition, a detailed troubleshooting section for particle size analysis can be found in unit d.u however, the difficulty of properly conducting accelerated tests should again be stressed. While the method is extremely useful, as it can drastically reduce the required time for the overall test, results may not accurately reflect... 

The final component we need to consider is the instrumentation and control system (Figure 14-10). Good instrumentation is vital to ensure that an extrusion line is operating efficiently and to troubleshoot extrusion problems. Because we cannot see inside the extruder, nor would we leam much even if we could, instrumentation serves as a window onto the process. Monitoring an extrusion system has been compared to monitoring a patient in the hospital you always need to measure vital signs, like blood pressure and body temperature. Likewise, an extrusion line that is not properly monitored can... 

The primary factors that affect the flowability of the final blend (or almost any powder), such as moisture content, particle shape/size/distribution, temperature/humidity and others, are discussed in more detail later in this chapter. Note that the measurement of flow properties and the design parameters they provide can also be applied to troubleshooting and developing corrective actions for flow problems in the preblending steps. 

Troubleshoot the reaction system to deduce the problems for an exothermic and an endothennic reaction. Next, suggest measures to correct the problem. You can change, and along with T, and Ty... 

Initially, look at an experimental to determine whether the 2° antibody labeling is as expected. Next, examine the 2° antibody control section to confirm no labeling. Finally, determine that there are no other labeling problems (e.g., background labeling) and that the level of labeling is acceptable. If there are problems with these conditions, then repeat the experiment with corrective measures (Chapter 14, Troubleshooting). Otherwise proceed to evaluate the results of the experiment and determine if the results meet your scientific expectations. 

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