Design of Technical Measures

There are also other forms of containment to consider. The first is mechanical protection in the sense that it protects the environment from missiles or flying debris when the reactor bursts, for example, by placing the equipment in a bunker. This approach is often used for high-pressure laboratory equipment, but in principle, may also be used for industrial equipment. The bunker is generally open to a safe place, where nobody can be harmed. 

A tight closed room can also be used as a containment area, providing enough volume for the effluent to be contained, giving time for the subsequent treatment of relieved material by, for example, a scrubber system. These types of measures should only be considered as a last resort, since they are linked with heavy damage to the equipment. An alternative is the safe-bag retention system, proposed by Siemens [38]. 

The choice and design of technical protection measures against runaway is in accordance with the risk level. This means that the consequences and controllability of the commencing runaway must be assessed. The criticality classes, based on four characteristic temperatures, are at the root of this assessment and serve in the design of protection measures. 

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Thus, a reliable technical measure is required. It may be designed in the same way as for class 3, but the additional heat release rate due to the secondary reaction has also to be taken into account. The use of thermal characteristics of the scenario in the design of technical measures is presented in detail in Chapter 10. 

The first measure is to use the evaporative cooling or controlled depressurisation to keep the reaction mass under control. The distillation system must be designed for such a purpose and has to function, even in the case of failure of utilities. A backup cooling system, dumping of the reaction mass, or quenching could also be used. Alternatively, a pressure relief system may be used, but this must be designed for two-phase flow that may occur, and a catch pot must be installed in order to avoid any dispersion of the reaction mass outside the equipment. Of course, all these measures must be designed for such a purpose and must be ready to work immediately after the failure occurs. The use of thermal characteristics of the scenario for the choice of technical measures is presented in detail in Chapter 10. 

This has essential consequences for the design of emergency measures. A technical measure to prevent a runaway could be a temperature alarm set at, for example, 10 K above the process temperature. This works well with nth-order reactions, where the alarm is activated at approximately half of the TMRld. However, autocatalytic reactions are not only accelerated by temperature, but also by time. This can lead to a sharp temperature increase. In the case shown in Figure 12.2, a temperature alarm is not effective, because there is no time left to take measures in the example given, only a few minutes are left before runaway. Therefore, it is important to know if a decomposition reaction is of autocatalytic nature or not that is, the safety measures must be adapted to this type of reaction. 

Noise reduction may be realized by means of a variety of technical measures. The measures include source noise reduction (e.g. noise generated by machines, woiking processes and procedures), noise reduction by noise absorption (e.g. by nsing shields, screens, absorbing panelling), noise reduction on designated locations (e.g. soundproof cabins, personal ear-protective equipment). 

Viscosity is a measure of a fluid s resistance to flow. The knowledge of viscosity is needed for proper design of required temperatures for storage, pumping, or injection of hazardous fluids. Define the viscosity terminologies, and provide technical data of typical liquid pollutants for illustration. 

McGowen, J.M. and McDaniel, B.W. "The Effects of Fluid Preconditioning and Test Cell Design on the Measurement of Dynamic Fluid Loss Data," SPE paper 18212, 1988 SPE Annual Technical Conference and Exhibition, Houston, October 2-5. 

For products in Class I, the manufacturer must have specified technical documentation on the design of the product showing that it conforms to the essential requirements manufacturing aspects are not covered and a notified body is not involved imless there is a measuring function and/or the product is sterilised. (Annex VII EC declaration of conformity.)... 

Automation of experiments in process development groups, particularly in combination with design of experiments (DOE), have been the focus of extensive work, including a special section in the journal Organic Product Research and Development,16 but a preponderance of the published work in this field still cites near-line or off-line HPLC for analysis. A number of application notes and technical reports that describe on-line spectroscopic measurements can be found at some of the automation vendors sites, such as Mettler Autochem and Argonaut.17... 

This example shows that the design of protection systems must be careful and thought through, to be efficient in any emergency. Further, it also enhances the fact that technical measures may fail. Absolute reliability can never be guaranteed. 

Similar to HRQL surveys, patient satisfaction instruments are designed to be general or specific instruments. One of the most commonly used instruments is the Patient Satisfaction Questionnaire (PSQ). This survey measures global satisfaction, as well as the specific domains of technical quality, interpersonal manner, communication, financial aspects, time spent with the doctor, and accessibility of care (Fincham and Wertheimer, 1987 Larson and MacKeigan, 1994 MacKeigan and Larson, 1989). 

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