Selection procedures

To select the number of corrugations required, the induced angular rotation must be determined. The moment required to rotate the joint must be calculated, if end-moments and forces (transmitted to sensitive equipment nozzles) are required. 

Angular Rotation. Generally, the angular rotation be obtained as follows  

Applying the above to the initial point E, we obtain the following  

This relationship can easily be proved geometrically. Assuming that the maximum allowable 0 for one corrugation is known from manufacturer s data, the number of corrugations required per joint can now be determined. 

The moment M, required to rotate the joint, can also be computed provided M ax is known  

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Magnetic Content of Feed Solids. The magnetic content of the soHds is typically >60%. Conventional selection procedures can be used in such cases. When the magnetic content of the soHds falls below 60% the feed volume should be reduced and multidmm separators considered in order to maintain higher magnetic recovery. 

Feasibility Analysis The selection procedure is performed by an evaluation or technical and economic considerations. The technical evaluation determines whether a given option will work as planned. Some typical considerations follow ... 

In this section a selection procedure will be developed for injection moulding, since this process is used for the widest range of materials. The choice available for other processes such as, for example, compression moulding, filament winding and vacuum forming, is much more restricted. The approach described will be less mechanistic than the systems described in the two previous sections, requiring the prospective user to be aware of the properties of the various materials available. Because the approach is somewhat different, it would be instructive to run it parallel to the above processes and compare the results. 

However, in general these fabrication and performance advantages are common to all plastics and so a decision has to be made in regard to which plastic would be best for a particular application. Rather than compare the basic raw material costs it is better to use a cost index on the basis of the cost to achieve a certain performance. Consider again the material selection procedures illustrated in Section 1.4.1 in relation to strength and stiffness. 

In the bibliography to ISO/TS 16949 there is only one customer reference manual mentioned the QS-9000 Measurement Systems Analysis Manual. This provides excellent guidelines for selecting procedures to assess the quality of a measurement system. It includes an introduction to measurement systems, explains the factors that cause variation in a measurement system, has guidance for preparing for a measurement system study, and includes step-by-step procedures for determining the degree of each type of variation present in a measurement system. 

The initial aim of the procedure is to generate a reasonable base case design that can be used for preliminary economic evaluation of the process. This can subsequently be optimized and/or compared with any process alternatives that are identified. The complete process is always considered at each decision level, but additional fine detail is added to the structure of the flowsheet at any stage. Established heuristics and equipment selection procedures are used together with new process synthesis insights to guide each flowsheet decision. 

A probable selection procedure could take the following form ... 

The materials selection procedure for new or replacement plant is crucial to the safe and economic operation of that plant. There is no one correct way to select the appropriate construction material, since for small plant handling toxic or inflammable products the integrity of the plant is high in priority, whereas large plant producing bulk material in a competitive market is more likely to be made of cheaper constructional materials, and the occasional leak or failure may have fewer safety implications. 

The materials selection procedure should take into account the commissioning requirements of all parts of the plant in order not to include any materials that cannot safely be degreased or chemically cleaned. 

During the materials selection procedure isothermal corrosion testing may indicate the suitability of a material for handling a corrosive process fluid. In many cases where heat transfer is involved the metal wall temperature experienced in service is higher than the bulk process fluid temperature. This, and the actual heat transfer through the material, must be taken into account since both factors can increase corrosion rates significantly. 

The corrosion conditions can be different at the fluid line from the bulk condition. Aqueous liquids have a concave meniscus, which creates a thin film of liquid on the vessel wall immediately above the liquid line. Some corrosion processes, particularly the diffusion of dissolved gases, are more rapid in these conditions. Additionally, the concentration of dissolved gases is highest near the liquid surface, especially when agitation is poor. Locally high corrosion rates can therefore occur at the liquid line, leading to thinning in a line around the vessel. This effect is reduced if the liquid level in the vessel varies with time. Any corrosion tests undertaken as part of the materials selection procedure should take this effect into account. 

Plastics are families of materials each with their own special advantages. The major consideration for a designer is to analyze what is required as regards to performances and develop a logical selection procedure from what is available. 

Installation arrangements, 351 Pump-down time, 380 Selection procedure, 374 Specification form, 377 Specifications, 373 Steam jet comparison, 356 Types of loads, 359 Ejectors, 346 Applications, 353 Barometric condenser, 249, 376 Booster, 370 Calculations Actual air capacity, 362 Air equivalent, 360... 

The selected procedure has to comply with good manufactoring practice (GMP) rules and must be fully validated. 

The previous sections have summarized the basic techniques available for searching chemical databases for specific types of query. Another important database application is compound selection, the ability to select a subset of a database for submission to a biological testing program. The selection procedure can be applied to in-house databases, to externally available compound collections, or to virtual libraries, that is, sets of compounds that could potentially be synthesized. 

From this one ancestral fungus each penicillin manufacturer has evolved a particular production strain by a series of mutagenic treatments, each followed by the selection of improved variants. These selected variants have proved capable of producing amounts of penicillin far greater than those produced by the wild strain, especially when fermented on media under particular control conditions developed in parallel with the strains. These strain selection procedures have become a fundamental feature of industrial biotechnology. 

In any catalyst selection procedure the first step will be the search for an active phase, be it a. solid or complexes in a. solution. For heterogeneous catalysis the. second step is also deeisive for the success of process development the choice of the optimal particle morphology. The choice of catalyst morphology (size, shape, porous texture, activity distribution, etc.) depends on intrinsic reaction kinetics as well as on diffusion rates of reactants and products. The catalyst cannot be cho.sen independently of the reactor type, because different reactor types place different demands on the catalyst. For instance, fixed-bed reactors require relatively large particles to minimize the pressure drop, while in fluidized-bed reactors relatively small particles must be used. However, an optimal choice is possible within the limits set by the reactor type. 

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