Evaporation numbers

For the purpose of polymer/additive analysis it is useful to rank solvents according to their boiling point ranges into low boilers (b.p. <100°C), medium boilers (b.p. 100-150°C) and high boilers (b.p. >150°C). Based on their evaporation numbers, solvents can be subdivided into four groups high volatility (< 10), moderate volatility (10-35), low volatility (35-50) and very low volatility (>50). 

The results are termed evaporation numbers (Table 9) and are referred to diethyl ether = 1. Evaporation numbers are listed in Table 23. 

Solvents can be subdivided into four groups on the basis of their evaporation numbers ... 

Solvent Time, h Evaporation number (diethyl ether = 1)... 

Diethyl ether [60-29-7] (DEE, ethoxyethane, ether) is a clear, colorless, highly mobile liquid with a low boiling point and a characteristic pleasant odor. It is miscible in all proportions with common organic solvents such as alcohols, ketones, hydrocarbons, esters, and ethereal oils. Diethyl ether has an evaporation number of 1. 

The boiling-point rise can be considered negligible as well as the heat of solution. Each evaporator has a 1000-ft surface area and the heat-transfer coefficients are Ui = 500 and U2 = 700 btu/h ft °F. The feed enters evaporator number 2 and steam at 100 psia is fed to number 1. The pressure in the vapor space of evaporator number 2 is 0.98 psia. Assume that the heat capacity of all liquid solutions is that of liquid water. Calculate the feed rate F and the product rate Z, of a solution containing 25% solids. Hint Assume a feed rate of, say, F = 1000 Ib /h. Calculate the area. Then calculate the actual feed rate by multiplying 1000 by 1000/calculated area.)... 

The results relative to diethyl ether = 1 are termed evaporation number (EN), which is more commonly used in Europe. On the basis of these numbers, solvents are classified into four categories high volatility (EN < 10), medium volatility (EN 10 to 35), low volatility (EN 35 to 50) and very low volatility (EN > 50). In the United States, the volatility of a solvent is normally evaluated relative to butyl acetate = 1, and is classified as Class 1 (rapid evaporation, E > 3.0), Class 2 (moderate evaporation, 0.8 < E < 3.0) and Class 3 (slow evaporation, E < 0.8). 

Type of solvents Mol. Mass Boiling point/ region [°C] Density at 20° C [g/cm ] Refractive index at 20°C Evaporation number Vapor pressure at 20°C [hPa] Flash point [°C] Ignition temperature [°C] Explosion limit [Vol%]... 

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