# Need some Air Quality help



## FusionWhite (Aug 23, 2006)

Im working on with a client who is doing a research project on a new for of Soil Vapor Extractor. Im working on the air permit and am trying to get a handle on the emissions of VOC's out of the stack. The person who had previously done the calculations sent me a massive spreadsheet in which he came up with a flow rate of VOC's out of the stack at 4.5 lbs/hour.

Well heres the tricky part when I grabbed an air sample and had it sent off to the lab I got this data:

Concentration: 5000 ppm VOC's

Flow Rate: 350 ACFM

Molecular Weight of Contaminents: 242.70

The calculation I used was PPM*10^-6*MW*CFM*1440/386 (1440 and 386 are conversions for minutes per day and lb-moles/cubic foot respectively)

I ended up with 1.5 lbs/DAY. Much lower then the first guy. Well now we're in a pissing contest about whos right.

Long story short someone help me figure out the emissions of VOC's from the above numbers. I have more data but all the books Ive referenced say this is all I need to get a number close enough for an air permit.


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## RIP - VTEnviro (Aug 24, 2006)

Yes, this is a job for Super VTE!

I'll try the calc myself at some point when I get a chance today. It's basically a manipulation of the ideal gas law.

Is that concentration in ppmv? That's what I'm assuming.


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## RIP - VTEnviro (Aug 24, 2006)

orly I ran it quickly and got 1560 lb/day. I bet I messed up a conversion factor of 10^3 somewhere, because if you divide by 10^3 you get 1.5, which is the number you got.


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## FusionWhite (Aug 25, 2006)

After doing some research I found out that A) the MW of the contaminants was wrong and B) ppmv does not have to be corrected for temperature and pressure.

The ppmv part for correcting for temperature and pressure makes sense because your not worried about the state of 1mm particles your only worried about how many their are and it doesnt matter if they're at 1000 psi or 14.7 psi. After changing the MW in my spreadsheet I came up with 0.76 lbs/day which is still way below what the other guy calculated. The bad news is he has PhD and assumes Im a dumb ass and Im going on the theory he doesnt want to be proven wrong by some random guy at a consulting company.


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