I need to add a known amount of ethanol vapour to a gas mixture (He/Ar). To do that I let the mixture bubble in liquid ethanol kept at a known temperature (14 C).

The system is made of a large steel cylinder (d=20 cm; l=138cm) lying in horizontal position and half filled with liquid ethanol. the gas is bubbled trough the liquid on one side of the cylinder and extracted on the other side.

The gas-flow trough the system is usually pretty low (~100ml/min) but I would like to increase it to ~10l/min and I need to know if this leaves enough time for the ethanol vapour to approach its equilibrium vapour pressure.


1 Answer 1


Please note that I have never done this.

But are you sure that you want to rely on approximation/assumptions?

I realize that it needs additional changes to the experimental setup, but is measuring the ethanol concentration out of question? Gas sensors for ethanol are commercially available and a setup, in which they steer mass flow controllers is conceivable.

As a side note, you might be interested to see that ethanol sensors can be build in the lab:

A Novel Flexible Room Temperature Ethanol Gas Sensor Based on SnO2 Doped Poly-Diallyldimethylammonium Chloride.

  • 1
    $\begingroup$ Thanks for the reply! I would like to have at least an estimate, an upper limit on the maximum flux would be enough. I am also planning to measure the amount of evaporated ethanol after continuously flushing at high flux for a long time. For purity reasons, I would prefer not to use and ethanol sensor, but that it certainly a good idea. On the other hand if a rough calculation shows the bubbler is big enough I can save some money! :) $\endgroup$
    – muzzle
    Commented Feb 19, 2014 at 23:15
  • 1
    $\begingroup$ The article you linked is interesting, but building such a sensor is beyond the reach of my lab, unfortunately. $\endgroup$
    – muzzle
    Commented Feb 19, 2014 at 23:22

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