Evaporation rate 3

[mereaux]

Hello Everybody,

I am working on powder deposition with a solvent which evaporates. I have to change the actual solvent by another, which evaporates slower.
I have datasheets of the two solvents, it is indicated the evaporation rate and also a reference BUOAC=1. I do not understand what it means, how I can compare the two solvents, and how is done this measurement. Anyone have an idea? Can I take this rates and just say that one is 40 (by comparaison of the given rate ) time slower to evaporate?

Thank you.

Mereaux

 

[owg]

The usual standard is butyl acetate = 1. That seems to be fairly close match to BUOAC. I would use a correlation which uses vapour pressure, temperature, wind or ventilation conditions, and possibly humidity, to determine the evaporation rates in #/min/sq ft or the units of your choice. However the 40:1 approach may be OK as a first approximation.

HAZOP at

http://www.curryhydrocarbons.ca

 

[mereaux]

OWG,

Thank you very much for your quick answer!
What do you mean by correlation? Do you know such correlation available for all solvent?
Could you explain me it?

thank you.

Mereaux

 

[mbeychok]

Mereaux:

You can find evaporation rate correlations you want by visiting either www.air-dispersion.com/msource.html (in metric units) or www.air-dispersion.com/usource.html (in the customary USA units).

For either of the above, select "Evaporation From A Non-boiling Pool" and you will find three alternative methods for the calculating the evaporation rate of liquid pools or liquids in roofless tanks. The key parameters are vapor pressure of the liquid, temperature of the liquid, and the velocity of air movement across the surface of the liquid.

Milton Beychok
(Contact me at www.air-dispersion.com)

 

[owg]

I agree with Milton. That USAF correlation is the one I would use. He has documented it better than I ever could.

HAZOP at

http://www.curryhydrocarbons.ca

 

[enviroq]

mbeychok,

Thanks for the reference, I was looking for a formula for an evaporation rate of a surface spill.

This should work out fine for me.

Thanks!

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