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"ventilation - Requirements For Accumulated Flammable Vapors"


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#1 Lawlor Vincent

Lawlor Vincent

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Posted 09 March 2012 - 05:27 AM

Dear people,

I have a question regarding the

"VENTILATION - requirements for accumulated flammable vapors"

ww.cheresources.com/flammable.pdf

A formula is provided in order to calculate the "rate of evaporation"

The problem I have is that two of the terms are not defined

"R g" and "T l"

I though that R g was the universal gas constent but regardless of the units none seem to fit. I am also not sure what T L should be. I tried solving in excel but no variations in order to provide the given answer fit.

Can anybody help

Many thanks

#2 Lawlor Vincent

Lawlor Vincent

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Posted 09 March 2012 - 07:51 AM

Might be the following

Computations made by the Evaporation Calculator

The calculator uses the following equation (Kawamura and Mackay 1985) to estimate evaporation rate:

E = A * Km * (Mw * Pv)/(R * T) (kg/s)

where E = evaporation rate, in kg/s, A = area of the evaporating puddle, in m^2, Km = mass transfer coefficient, in m/s, Mw = molecular weight of the selected chemical, in kg/kmol, Pv = vapor pressure, in Pa (from the partial pressure table for the selected chemical), R = the gas constant (8314 J/(kmol K)), and T = ambient temperature, in K. The evaporation of the fraction of the solution that is water is ignored since water isn't a hazardous chemical.

The units still don't fit the problem stated in:

ww.cheresources.com/flammable.pdf




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