Pressure-temperature nomograph

The line drawn from point A to C intersects chart B to give the theoretical b.p. at 760 mm 

Line up point B figured in step 3 with another pressure (chart C) 

Extend the line BC through chart A to approximate the corresponding b.p. 

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DePriester, C. L. Light-Hydrocarbon Vapor-Liquid Distribution Coefficients, Pressure-Temperature-Composition Charts and Pressure-Temperature Nomographs Chem. Eng. Progress Symp. 1953, 7, 49. 

Many compounds decompose when heated to their boiling points so they cannot be distilled at atmospheric pressure. In this situation it may be possible to avoid thermal decomposition by carrying out the distillation at reduced pressure. The reduction in the boiling point will depend on the eduction in pressure and it can be estimated from a pressure-temperature nomograph (Fig. 11.11). 

The boiling point of a substance at various pressures can be estimated from a pressure-temperature nomograph such as the one shown in Fig. 10. If the boiling point of a substance at 760 mm Hg is known, e.g., 300°C (Column B), and the new pressure measured, e.g., 10 mm Hg (Column C), then a straight line connecting these values on Columns B and C when extended intersects Column A to give the observed bp of 160°C. Conversely, a substance observed to boil at 50°C (Column A) at 1.0 mm Hg (Column C) will boil at approximately 212°C at atmospheric pressure (Column B). 

An unknown carboxylic acid has a boiling point of 100 °C at 25 torr. Using the pressure-temperature nomograph on page 49, determine its boiling point at 760 torr. Identify the acid from the list in Appendix A, Table 9W.1. 

FIG. 10 Pressure-temperature OBSERVED nomograph. BOILING POINT... 

Pressure-temperature alignment nomograph. How to use the nomograph Assume a reported boiling point of 100°C (column A) at 1 mm. To determine the boiling point at 18 mm, connect 100°C (column A) to 1 mm (column C) with a transparent plastic rule and observe where this line intersects column B (about 280°C). 

Pressure-temperature alignment nomograph (dashed lines added for illustrative purposes). How to use the nomograph Assume a reported boiling point of 120 °C at 2 torr. 

Fig. 6 Dew-point nomograph that correlates pressure, temperature, and water content (As shown, at 1.0 atm tmd 0°C, the dew point is 6,(XX) ppm of water). (Reprinted from [72] with permission of ASM International)...

Viscosities of Gases Coordinates for Use with Fig. 2-32.. . . Nomograph for Determining a) Absolute Viscosity of a Gas as a Function of Temperature Near Ambient Pressure and (h) Relative Viscosity of a Gas Compared... 

FIG. 2-32 Nomograph for determining (n) absolute viseosity of a gas as a fnnotion of temperature near ambient pressure and (b] relative viseosity of a gas compared with air. For ooor-dinates see Table 2-.3G4. To oonvert poises to pasoal-seoonds, multiply by 0.1. [From Beennan Meas. Control, 154-157 (June 1982).]... 

Fauske [32] represented a nomograph for tempered reaetions as shown in Figure 12-35. This aeeounts for turbulent flashing flow and requires information about the rate of temperature rise at the relief set pressure. This approaeh also aeeounts for vapor disengagement and frietional effeets ineluding laminar and turbulent flow eonditions. For turbulent flow, the vent area is... 

In many laboratories, a nomograph (see Figure 5.7) is pinned to the wall behind a rotary evaporator. A nomograph allows for a simple estimate of the boiling temperature as a function of pressure. Typically, pressure is expressed in the old-fashioned units of atmospheres (atm) or millimetres of mercury (mmHg). 1 atm = 760 mmHg. (The curvature of the nomograph is a consequence of the mathematical nature of the way pressure and temperature are related see Section 5.2). 

Figure 5.7 A typical nomograph for estimating the temperature at which a pure liquid boils when the pressure is decreased...

SAQ 5.1 A liquid has a normal boiling temperature of 140°C. Use the nomograph to estimate the applied pressure needed to decrease the boiling temperature to 90°C. 

You ve found all the leaks and the pressure in your vacuum distillation setup is, say, 25 torr. Now you need to know the boiling point of your compound, 1-octanol, this time at 25 torr and not 760 torr. You realize it ll boil at a lower temperature, but just how low The handy nomographs in (Figs. 76 and 77) can help you estimate the new boiling point. 

The heats of vaponzution at the boiling points for bromo-benzene, chlorobenzene and fluorobcnzcnc are available The hem of vapori/iiiion of benzyl chloride at 2VC has hern drier mined Ironi vapor pressure duui 272 The data weie evtended over a wider temperature range by the Khurbaruto nomograph J... 

The true instrumental method of analysis requires no reduction of data to normal pressure and temperature, no corrections or computations, no reference to correction factors nor interpolation on nomographic charts. It indicates the desired information directly on a dial or counter and if it is desired to have the answer printed on paper—that can be had for the asking. (Muller, 1947, pp. 23A-24A)... 

The calculated sets of temperatures, flow rates, and compositions obtained by the calculational procedure developed below are presented in Tables 4-14 through 4-16. These results were obtained by use of the data of Cecchetti et al. for the K values and enthalpies of the pseudo components. Curve fits of these data are presented in Tables B-14 and B-16. The K values for water / = 35 was taken from nomographs given by Hadden and Grayson,12 and the enthalpies from the steam tables given by Smith and Van Ness.21 In the condenser, the was taken equal to its vapor pressure (as given in the steam tables) divided by the total pressure in the condenser. 

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