Study of capillary condensation of butane in a Vycor glass membrane

Differences between the gas flux (at both sides of the membrane the butane is in the gas phase) and the liquid butane flux (on the high pressure side of the membrane is liquid, on the opposite side is gas) were observed for the same pressure gradients across the membrane. The differences between these fluxes decrease with decreasing pressure gradients. For a pressure gradient higher than 2 bar the flux of the liquid butane is approximately two times higher, for a pressure gradient of 1.3 bar the ratio of liquid and gas fluxes decreases to 1.7. No difference between liquid and gas fluxes was registered for the lowest pressure gradient investigated (pressures on the two sides of the membrane: 2.22 and 1.91 bar). From the results obtained it can be concluded that the condensation of butane in pores occurs at high pressures on both sides if simultaneously the pressure difference is small.