Methanol vapour transport

Table 4.3 Comparison of the transport properties of dichloromethane and methanol vapour in Hyflon AD80X at 25 °C...

This is the ratio between the molecular weight of the solvent and the molecular weight of air. Apart from methanol, which has the lowest vapour density of any liquid solvent, all organic solvents are appreciably denser. This means that spillages, whether on a small scale in the laboratory or on a large scale in transport or in an industrial plant, will give rise to vapour at a low level. Ventilation should therefore be designed to draw from this level and tests for flammable or toxic concentrations should be made at a low point. 

In this work preliminary vapour permeation measurements were carried out with two different species, the rather bulky dichloromethane (DCM) molecules and the much smaller methanol molecules. Two typical permeation curves are displayed in Figure 4.8. The transport parameters, determined on the basis of the tangent method and Equations (4.9)-(4.11), are listed in Table 4.3. It contains the parameters dehned above as well as solubility C in the membrane in equilibrium with the feed pressure of penetrants. 

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