leaving the housing through the retentate outlet 26 if multiple modules are contained in one housing the retentate from the first becomes feed for the second and so on the permeated components 6 a permeate from the feed spacer 4 into the hydrophilic skin of the microporous hydrophobic membrane 18 then into the solvent 7 contained in the pores of the microporous support membrane a selective separation occurs which is based on the extractive characteristics of the solvent for the feed components from there the permeated components diffuse into the solvent in the solvent spacer 16 and then permeate through the pervaporation membrane 14 a second selective separation occurs in the pervaporation membrane based on its permselectivity for the components in the solvent the permeate spacer is under vacuum conditions the permeate exits the pervaporation membrane as a vapor which travels through the permeate spacer 12 and into the permeate collection tube 1 the permeate vapor exits the module through either permeate outlet 22 external to the module housing are one or more condensers not shown for condensing the permeate vapor followed by a vacuum pump the feed if a liquid is supplied to the module via a pump at relatively low pressures since small amounts of solvent will be lost via permeation either into the retentate or the permeate streams makeup solvent is supplied via the makeup solvent inlet 24 on the module the makeup solvent flows into the exposed edges of the solvent spacers 16 in the outer circumference of the module and spirals inwards within the spacers to replenish lost solvent in the supported liquid membrane generally this.