Selection of Flow Path

Selection of Flow Path In selecting the flow path for two fluids through an exchanger, several general approaches are used. The tube-side fluid is more corrosive or dirtier or at a higher pressure. The shell-side fluid is a liquid of high viscosity or a gas. 

In catalytic processes, such as CO conversion (CO + H20 —> C02 + H2), selective methanisation (CO + 3 H2 —> CH4 + H20) or selective CO oxidation (CO + Vi 02 —> C02), the achievable efficiencies depend on reaction parameters, such as temperature, pressure, volume flow, raw gas concentration and catalyst material. These are capable of achieving contamination levels from 1 % down to a few ppm. The selection of different reaction paths is based on the use of different types of catalyst. 

The equivalent circuit corresponding to this resistive network is shown in Fig. 7.8. The current that carries the information about the analyte flows through the path of the lowest resistance. This seemingly trivial circuit can help us to design the best strategy for selectivity of amperometric sensors. 

In order to achieve highest sensitivity of VitD metabolites detection, the efforts for method development were focused on three components of the analytical flow path (1) the selective SPE extraction procedure, (2) the ionization and SRM method for MS/MS, and (3) the pLC loading and separation method. 

When operating conditions cannot be changed, one can select a valve with a treacherous flow path, either of the multiple-port or multiple-flow-path variety. Valves that are most likely to cavitate are the high-recovery valves (ball, butterfly, gate) having low FL and Fc coefficients (Table 2.67). Therefore, if cavitation is anticipated, low recovery valves with high Fc and FL coeffi-... 

The resolution achievable by a system depends upon the number of theoretical plates generated by that system and upon the selectivity of the system. The number of theoretical plates can be varied widely with separation path length, flow conditions, field strength, etc., and is thus highly variable. However, selectivity 1s a more Intrinsic property of the fractionation method and serves as a basis of comparison of the different systems. 

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