Orifice flow

Flow. The free flow of a powder through an orifice depends on the orifice which is standardized for the testing of the powder (14). Flow, therefore, depends not only on friction between powder particles, but also on friction between the particles and the wall of the orifice. Flow is usually expressed by the time necessary for a specific amount of powder (usually 50 g) to flow through the orifice. 

Sedimentation Tanks These tanks are an integral part of any activated-sludge system. It is essential to separate the suspended solids from the treated liquid if a high-quality effluent is to be produced. Circular sedimentation tanks with various types of hydraulic sludge collectors have become the standard secondary sedimentation system. Square tanks have been used with common-wall construc tion for compact design with multiple tanks. Most secondary sedimentation tanks use center-feed inlets and peripheral-weir outlets. Recently, efforts have been made to employ peripheral inlets with submerged-orifice flow controllers and either center-weir outlets or peripheral-weir outlets adjacent to the peripheral-inlet channel. 

As shown in Figs, 26-70 and 26-71, the orifice flow predic tions by the NEM (open points) are larger than those of the HEM, although still low compared with these particular data,... 

Calculations of Orifice Flow Area for Conventional Pressure Relieving Valves, and Flow is Critical (sonic) Through Part of Relieving System, i.e., backpressure is less than 55% of the absolute relieving pressure (including set pressure plus accumulation). See Figure 7-7A, use... 

Calculations of Orifice Flow Area using Pressure Relieving Balanced Bellows Valves, with Variable or Constant Back Pressure. Must be used when backpressure variation exceeds 10% of the set pressure of the valve. Flow may be critical or non-critical for balanced valves. All orifice areas. A, in sq in. [68]. The sizing procedure is the same as for conventional valves listed above (Equations 7-10 ff), but uses equations given below incorporating the correction factors K, and K,, . With variable backpressure, use maximum value for P9 [33a, 68]. 

Figure 13-6C. Effects of pulsation filter on orifice flow meter charts at 300 rpm compressor speed. (A) Before peak-to-peak differential pulsations were 160 psi, and (B) after installation of filter pulsation, levels dropped to 1.5 psi. (Used by permission von Nimitz, W. W., and O. Flanigan, Oil and Gas Journal, p. 60, Sept. 8, 1980. PennWell Publishing Company. All rights reserved.)...

Accounting, plant construction costs, 48 Cost accumulation, 49 Affinity laws, 201, 202, 203 Air Inleakage, vacuum systems, see vacuum systems Air pressure drop, table, 106 Chart, 114 Orifice flow, 107 Air, absolute viscosity, 132... 

NPSH (available from system, A), 160 NPSH (required by pump, R), 160 Operating pressure, 408 Operational check-list, safety relief, 428 Orifice areas, relief valves, 437 Sharp edge, 440 Orifice, flow, 82, 83, 119 Air, table, 107 Overpressure, 403 Causes, 427... 

An orifice flow configuration is more suitable for applications requiring intense cavitational conditions, whereas for milder processes (requiring collapse pressure pulses typically between 15 and 20 bar) and for transformations based on physical effects, a venturi configuration is more suitable and energy efficient. 

Yan Y, Thorpe RB, Pandit AB (1988) Cavitation noise and its suppression by air in orifice flow. In Proceedings of the International Symposium on Flow Induced Vibration and Noise, Chicago, ASME, pp 25 10... 

Pipe and Orifice Flow for Subcooled Liquids Since liquids are essentially incompressible, e is constant at e0, and de is zero in Eq. (23-42). Recognizing that r 0 and e0 are unity, we see that integration... 

The solution for orifice flow is a special case with N equal to unity (entrance losses only) and Zq equal to zero, giving... 

Numerical Solution for Orifice Flow With orifice flow, the last two terms of the momentum balance (line resistance and potential energy change) are negligible. The momentum balance, Eq. (23-40), reduces to... 

FIG. 23-34 Numerical solution of the momentum balance for orifice flow using Eqs. (23-56) and (23-59). 

The omega method HEM solution for orifice flow is plotted in Fig. 23-36. The solution for flashing liquids without noncondensables is to the right of = 1, and the solution for frozen flow with subcooled liquids plus noncondensables is to the left. The omega method HEM solution for horizontal pipe flow is plotted in Fig. 23-37 as the ratio ot pipe mass flux to orifice mass flux. 

For orifice flow, the definition of choked flow in terms of the backpressure ratio % is... 

FIG. 23-36 Omega method solution for orifice flow of flashing liquids and for noncondensable gas plus subcooled liquids. 

Sutherland (1975). Orifice flow rates are underpredicted by about the same factor with the energy balance method and with the NEM. Discharge predictions for short (0.2-m) pipes are overpredicted by the energy balance method. In this region, the assumption of homogeneous equilibrium is not justified. A model that takes slip velocity into account may improve predictions for short pipes. 

Gas flow through the sampling orifice is of interest since its volume rate of flow determines the size of vacuum pumps necessary for the mass spectrometer. In addition, orifice flow behaves as a first-order removal process that can lead to erroneous kinetics if it is too large. The perturbation of flow in the reactor has been discussed in Section IV.B. 

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