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Partial flow ratio

The partial flow concept is usually used in making the connection of a helium leak detector to vacuum systems with multi-stage vacuum pump sets. When considering where to best make the connection, it must be kept in mind that these are usually small, portable units which have only a low pumping speed at the connection flange (often less than 1 l/s). This makes it all the more important to estimate - based on the partial flow ratio to be... [Pg.121]

Partial flow ratio = Fraction of the overall flow to the leak detector... [Pg.121]

FIG. 8. (a) The total and partial pressures p and (b) the partial pressure ratio of silane and hydrogen in a silane-hydrogen mixture, at different flow ratios The total flow rate is 30 seem. (Adapted from E. A. G. Hamers. Ph.D. Thesis. Universiteit Utrecht. Utrecht, the Netherlands. 1998. with permission.)... [Pg.26]

For a completely homogeneous mixture, sc = 0 and thus v=0. Usually, two partial flows are combined in a mixing process. The volumetric flow ratio of the side stream with respect to the main stream is defined as ... [Pg.174]

In initial studies in which substance P was administered to subjects by intravenous infusion, no effect on airway caliber could be demonstrated. It is possible that potent cardiovascular side effects resulted in homeostatic reflexes with secondary effects on the airways that masked the effects of substance P (Fuller et al., 1987). However, when changes in the partial flow volume curve, a highly sensitive index of airway caliber, were used as the index of airway obstruction, inhaled NkA - and, to a lesser extent, inhaled substance P - caused airway obstruction in healthy people (Joos et al., 1987). NkA is approximately 10-100 times more potent as a bronchocon-strictor in asthmatic than in non-asthmatic subjects (Cheung et al., 1992, 1993) this ratio of potency is similar to that observed for other agonists. [Pg.127]

In an attempt to unravel the kinetics of the SiH2Cl2/WF6 chemistry, Srinivas et al.237, set up their experimental conditions such that the reactant conversion would be less than 10%. In this situation one can assume that the reactor is gradientless and inlet partial pressures (calculated from inlet flow ratios and the pressure) will be close to true wafer surface partial pressures. In calculating the conversion degree, however, one should keep... [Pg.195]

Figure 6. Axial partial pressure profiles in the maternal channel for various maternal to fetal volumetric flow ratios. Maternal volumetric flow rate held... Figure 6. Axial partial pressure profiles in the maternal channel for various maternal to fetal volumetric flow ratios. Maternal volumetric flow rate held...
Note that in the above formulation both extensive and intensive variables are included, in contrast with the phase rule, where only intensive variables are considered Typical Ny variables are temperatures and pressures, partial flows, specific enthalpies, chemical potential or fugacities of components, heat duty and mechanical work, recycle ratios and split fractions. Be careful not to include in the list interdependent variables. [Pg.81]

The detectable threshold leakage rate Qt resh results from the ratio of pumping speeds of the respective system vacuum pump Sp p and the helium leak detector pump Spo (partial flow factor) multiplied by the minimum detectable leakage rate... [Pg.179]

The axial distributions of parameters for two study cases are shown on Figs. 3, 4. In the first case particles are absolutely elastic. In the second case they are partially inelastic and lose k=5% of the energy of chaotic motion at each collision. The solids/gas mass flow ratios... [Pg.695]

Fig. 4. Axial distributions of parameters of the gas of partially inelastic particles for various particle diameters. Solids/gas mass flow ratio p = 10. Fig. 4. Axial distributions of parameters of the gas of partially inelastic particles for various particle diameters. Solids/gas mass flow ratio p = 10.
For the case where the steam valve is manipulated by some variable other than flow or flow ratio, we may need to account for reboiler dynamics to calculate qr- Referring to Figure 15.8, we may make a partial s al flow diagram as shown on Figure 17.4 where ... [Pg.406]

It is normal practice to consider a partially full gravity flow pipeline as a full flow pipeline of a smaller, equivalent diameter. The equivalent diameter matches all the hydraulic characteristics of the larger, partial flow gravity pipeline. The velocity, GPM flow rate and slope are identical in each case. The equivalent diameter is four times the hydraulic radius. The hydraulic radius for partial flow gravity pipelines is defined as the ratio of the cross-sectional flow area divided by the wetted perimeter. [Pg.73]

Because back pressure is more than the critical pressme, the flow will be subcritical. Nonflashing and flashing partial pressme ratios are estimated using Equahon 4.81 and Equahon 4.82. [Pg.330]

Detection limit. The detection limit of an instrument should be differentiated from its sensitivity. The detection limit reflects the smallest flow of sample or the lowest partial pressure that gives a signal that can be distinguished from the background noise. One must specify the experimental conditions used and give the value of signal-to-noise ratio corresponding to the detection limit. [Pg.436]

Other techniques include oxidative, steam atmosphere (33), and molten salt (34) pyrolyses. In a partial-air atmosphere, mbber pyrolysis is an exothermic reaction. The reaction rate and ratio of pyrolytic filler to ok products are controlled by the oxygen flow rate. Pyrolysis in a steam atmosphere gives a cleaner char with a greater surface area than char pyroly2ed in an inert atmosphere however, the physical properties of the cured compounded mbber are inferior. Because of the greater surface area, this pyrolytic filler could be used as activated carbon, but production costs are prohibitive. Molten salt baths produce pyroly2ed char and ok products from tine chips. The product characteristics and quantities depend on the salt used. Recovery of char from the molten salt is difficult. [Pg.15]

An important characteristic of solvents is rate of evaporation. Rates of solvent loss are controUed by the vapor pressure of the solvent(s) and temperature, partial pressure of the solvent over the surface, and thus the air-flow rate over the surface, and the ratio of surface area to volume. Tables of relative evaporation rates, in which -butyl acetate is the standard, are widely used in selecting solvents. These relative rates are deterrnined experimentally by comparing the times required to evaporate 90% of a weighed amount of solvent from filter paper under standard conditions as compared to the time for -butyl acetate. The rates are dependent on the standard conditions selected (6). Most tables of relative evaporation rates are said to be at 25°C. This, however, means that the air temperature was 25°C, not that the temperature of the evaporating solvent was 25°C. As solvents evaporate, temperature drops and the drop in temperature is greatest for solvents that evaporate most rapidly. [Pg.342]

Example 8 Calculation of Rate-Based Distillation The separation of 655 lb mol/h of a bubble-point mixture of 16 mol % toluene, 9.5 mol % methanol, 53.3 mol % styrene, and 21.2 mol % ethylbenzene is to be earned out in a 9.84-ft diameter sieve-tray column having 40 sieve trays with 2-inch high weirs and on 24-inch tray spacing. The column is equipped with a total condenser and a partial reboiler. The feed wiU enter the column on the 21st tray from the top, where the column pressure will be 93 kPa, The bottom-tray pressure is 101 kPa and the top-tray pressure is 86 kPa. The distillate rate wiU be set at 167 lb mol/h in an attempt to obtain a sharp separation between toluene-methanol, which will tend to accumulate in the distillate, and styrene and ethylbenzene. A reflux ratio of 4.8 wiU be used. Plug flow of vapor and complete mixing of liquid wiU be assumed on each tray. K values will be computed from the UNIFAC activity-coefficient method and the Chan-Fair correlation will be used to estimate mass-transfer coefficients. Predict, with a rate-based model, the separation that will be achieved and back-calciilate from the computed tray compositions, the component vapor-phase Miirphree-tray efficiencies. [Pg.1292]

Figure 1 Is a flow sheet showing some significant aspects of the Iterative analysis. The first step In the program Is to Input data for about 50 physical, chemical and kinetic properties of the reactants. Each loop of this analysis Is conducted at a specified solution temperature T K. Some of the variables computed In each loop are the monomer conversion, polymer concentration, monomer and polymer volume fractions, effective polymer molecular weight, cumulative number average molecular weight, cumulative weight average molecular weight, solution viscosity, polymerization rate, ratio of polymerization rates between the current and previous steps, the total pressure and the partial pressures of the monomer, the solvent, and the nitrogen. Figure 1 Is a flow sheet showing some significant aspects of the Iterative analysis. The first step In the program Is to Input data for about 50 physical, chemical and kinetic properties of the reactants. Each loop of this analysis Is conducted at a specified solution temperature T K. Some of the variables computed In each loop are the monomer conversion, polymer concentration, monomer and polymer volume fractions, effective polymer molecular weight, cumulative number average molecular weight, cumulative weight average molecular weight, solution viscosity, polymerization rate, ratio of polymerization rates between the current and previous steps, the total pressure and the partial pressures of the monomer, the solvent, and the nitrogen.
Recycling of partially reacted feed streams is usually carried out after the product is separated and recovered. Unreacted feedstock can be separated and recycled to (ultimate) extinction. Figure 4.2 shows a different situation. It is a loop reactor where some of the reaction mass is returned to the inlet without separation. Internal recycle exists in every stirred tank reactor. An external recycle loop as shown in Figure 4.2 is less common, but is used, particularly in large plants where a conventional stirred tank would have heat transfer limitations. The net throughput for the system is Q = but an amount q is recycled back to the reactor inlet so that the flow through the reactor is Qin + q- Performance of this loop reactor system depends on the recycle ratio qlQin and on the type of reactor that is in the loop. Fast external recycle has... [Pg.139]


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See also in sourсe #XX -- [ Pg.121 ]




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