Valve interactions

Kunadian, B. et al.. Should the tricuspid valve be replaced with a mechanical or biological valve Interact Cardiovasc Thorac Surg, 2007. 6(4) p. 551-7. 

For a better understanding of the interactions between parameters, it is often helpful to calculate the effective bubble rise velocity from measurea valves of for example, the data of Mersmann (loc. cit.) indicated = 0.6 for = 0.05 iti/s, giving U, = 0.083 m/s, which agrees with the data reported in Fig. 14-43 for the rise velocity of bubble clouds. The rise velocity of single bubbles, for d - 2 mm, is about 0.3 m/s, for liquids with viscosities not too different from water. Using this value in Eq. (14-220) and comparing with Fig. 14-104, one finds that at low values of the rise velocity of the bubbles... 

It is not a bad idea for the process engineer to familiarize himself with compressor surge controls. The interaction of the compressor surge controls with downstream process control valves can become a problem area later, and this study phase is not too early to put such items on a checklist. An LNG plant example comes to mind where such an operating problem existed. 

For the purpose of this chapter, instrumentation will be considered everything from the primary element monitoring the controlled variable through the control valve performing the throttling action. The process equipment interacts with the instrumentation to provide the process... 

Its unique design suggests several accident scenarios that could not occur at other reactors. For example, failure to supply ECC to 1/16 of the core due to the failure of an ECC inlet valve. On the other hand, some phenomena of concern to other types of reactors seem impossible (e.g., core-concrete interactions). The list of phenomena for consideration came from previous studies, comments of an external review group and from literature review. From this, came the issues selected for the accident progression event tree (APET) according to uncertainty and point estimates. 

Interactions refers to any jobs, tasks, or operations carried out by people who could directly or indirectly cause the hazard to be released. Direct interactions with the plant might involve breaking open pipework, opening reactors, etc. Indirect interactions would include remote activation of valves from a control room, or the performance of maintenance on critical plant items. Errors that might occur during these interactions could allow the harm potential to be released. This could occur directly (for example, a worker could be overcome by a chlorine release if an incorrect valve line-up was made) or indirectly (for example, if a pump bearing in a critical cooling circuit was not lubricated, as in the example in Chapter 1). The procedure as described above... 

Purely electrical models of the heart are only a start. Combined electromechanical finite-element models of the heart take into account the close relationship that exists between the electrical and mechanical properties of individual heart cells. The mechanical operation of the heart is also influenced by the fluid-structure interactions between the blood and the blood vessels, heart walls, and valves. All of these interactions would need to be included in a complete description of heart contraction. 

In the case of suspension products of this type, the function should be considered based on the particle size of the active ingredient. The combination of active ingredient, propellant, co-solvent, and surfactant should be investigated. Potential for extraction and other interactions with the container system parts (including the valve mechanism) should be reported. 

Some general guidelines for the application of the proper valve characteristic are shown in Fig. 10-14. These are rules of thumb and the proper valve can be determined only by a complete analysis of the system in which the valve is to be used [see also Baumann (1991) for simplified guidelines]. We will illustrate how the valve trim characteristic interacts with the pump and system characteristics to affect the flow rate in the system and how to use this information to select the most appropriate valve trim. 

The apparatus and techniques of ion cyclotron resonance spectroscopy have been described in detail elsewhere. Ions are formed, either by electron impact from a volatile precursor, or by laser evaporation and ionization of a solid metal target (14), and allowed to interact with neutral reactants. Freiser and co-workers have refined this experimental methodology with the use of elegant collision induced dissociation experiments for reactant preparation and the selective introduction of neutral reactants using pulsed gas valves (15). Irradiation of the ions with either lasers or conventional light sources during selected portions of the trapped ion cycle makes it possible to study ion photochemical processes... 

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