Pressure drop Velocities, chart

For banks of in-line tubes,/for isothermal flow is obtained from Fig. 6-43. Average deviation from available data is on the order of 15 percent. For tube spacings greater than 3D(, the charts of Gram, Mackey, and Monroe (Trans. ASME, 80, 25—35 [1958]) can be used. As an approximation, the pressure drop can be taken as 0.32 velocity head (based on V ) per row of tubes (Lapple, et al.. Fluid and Paiiicle Mechanics, University of Delaware, Newark, 1954). 

Chart, 204, 205, 207 Vortex, 190 Water hammer, 98 Wire mesh separators, 246, 247 Calculations, 247-254 Efficiency, 248, 250 Installation, 251-253 k-value for mesh, table, 249 Mesh patterns, 247 Pressure drop, 249, 251 Specifications form, 254 Vapor velocity, 247, 250 Wire mesh types, 248... 

Figure 13.38. Capacity and pressure drop in beds of pall ( ballast ) rings (Glitsch, Inc.), (a) Capacity chart for pall rings. Vs = vapor velocity (ft/sec). Example with 1 in. rings,...

The final drum diameter is determined by checking a particular manufacturer s chart for the vapor velocity, entrainment load and pressure drop through the particular mesh pattern chosen (see Figure 5-3). Should the pressure drop be too high or too low, the diameter would be adjusted until it is acceptable. 

The design chart can also be conveniently used for vapor line sizing in general. Frequently, pipe lines are sized on the basis of vapor velocity or pressure drop AP/Pi (or AP) per 100 feet. If the mass flow rate, molecular weight and temperature of the vapor are given, the proper line size can be readily selected by means of Figure 6-13, where velocity lines and lines for AP/Pi per 100 feet are included. 

You may verify that these give the same entry point on the abscissa. Reading at the intersection of this pressure drop and 500 ft /min(cfm), we find that the required pipe diameter is about 8.2 in and the velocity is about 1350ft/min = 22.5 ft/s. The practically perfect agreement with Example 6.5 simply shows that Fig. 6.14 was made up by using the standard friction factor plot. The small differences between the density and viscosity of air at 70 and 40°F do not affect the answer to chart-reading accuracy. ... 

The determination of the flooding velocity in structured packings is best carried out by using interpolation of the flooding and pressure drop charts for individual structured packings in Chapter 10 of Kister (1992). 

A final approach to the problem of estimating pressure drop for random packings should not be overlooked test data from the packing vendors. These data usually are based on air-water and are taken in the vendor laboratories. They are presented in charts such as that shown in Fig. 5.8-13. In the example shown, pressure drop is given as a Ainction of gas mass velocity. For gases other than air, the abscissa should be multiplied by the square root of the ratio, air density to the density of the gas under consideration ... 

Maximum superficial condensate velocities are about 25 m s . In a given line, the velocity increases as the pressure drops and more liquid vaporizes. Vendors of steam traps and condensate systems can provide guidance and line-sizing charts. Water lines usually have velocities up to 3ms . The designer must consider water hammer as well as velocity and pressure drop. Selection of valves and their closure time becomes important. Compressed air usually is transported at 5-8 m s. ... 

Figure22.14 Condensate line sizing chart where pressure at traps is above 4bar (SI units). 1. From pressure upstream of trap move horizontally to pressure in return line (A). 2. Drop vertically to condensate load in kg/h (B). 3. Follow curve to RFI scale and across to same return line pressure (C). 4. Move upward to return line flash velocity - say, 25 m/s maximum (D). 5. Read return line size.

---