HCN & NH3 in Air

Seriously, would any CR4 reader confess if it were over these limits?

Why are these materials going up the stack when they have significant commercial application? It sounds as though there might be a containment problem somewhere.

Interesting response. It is fascinating to note the assumptions that minds come to when cyanide compounds are mentioned in particular. What most people do not realise is that hydrogen cyanide is a common product of combustion for example in cigarette smoke.

The objective here is to establish a global view on ELVs applied to these compounds in Industrial stack gas emissions where available.

Hmmm, The math says these are relatively low levels.

Cyanide: 1M^3= 1000 liters. 5 mg / liter is 5 ppm; in a cubic meter its 5 ppb. This study used .5ppm cyanide and did not show damage to lungs and vascular tissues in rabbits.

http://www.springerlink.com/content/v1qx8u5863214v4v/

I remember somewhere reading that the dosage is more important than the specie per se.

Ammonia: 20 ppm is a recommended standard for animal husbandry (Its present in urines) 10 ppb is way below the levels tested in this study:

http://www.ehsrc.uiowa.edu/CAFOstudy/CAFO_6-2.pdf

So the question remains is ammonia levels of 10ppb in a factory stack more "dangerous" than the <100ppm levels typical in the barn that farmers work in to raise our meat?

Interesting question.

The Occupational exposures for ammonia are:

Airborne Exposure Limits:
For Ammonia:
- OSHA Permissible Exposure Limit (PEL) -
50 ppm (TWA)
- ACGIH Threshold Limit Value (TLV)
25 ppm (TWA), 35 ppm (STEL).

And you are at 10ppb?

Any one who could do the math would call your stack "fresh air" compared to these exposure limits.

My normal take is always "protect the customer." But expecting some huge expense to get from 5ppb or 10 ppb to ZERO, my thoughtful response would be I'd live downwind of this before i would a hog barn.

milo

"Cyanide: 1M^3= 1000 liters. 5 mg / liter is 5 ppm; in a cubic meter its 5 ppb." Am I missing something here. Not to nit pic, but the conversion equation is as follows:

ppm=(mg/m³)(24.45)/(gram-molecular weight)

MW = 27.03. Therefore, ppm = (5 mg/m³ x 24.45) / 27.03 = 4.5 ppm (admittably close to 5). SGL reports 5 mg/m³, not per liter, so we are still considering significant ppm levels. Did I neglect something in my math?

HCN may be regulated by EPA as a hazardous air pollutant (cyanide compounds). The actual emission limits, if any, may be listed based on your industry. Check this EPA website and see if any of the classifications work for you. Please let me know if you find what your looking for.

http://www.epa.gov/ttn/atw/mactfnlalph.html

No problem, I see I was using "aquatic" rather than Gas methodology.

Interestingly the epa doesn't want mass per volume for ppm calculations either , they want volume to volume conversions:(ppmV or ppbV)

http://www.epa.gov/Athens/learn2model/part-two/onsite/ia_unit_conversion_detail.htm

At 5 ppm Calculated as you did, that is still just one half the occupational PEL.

http://www.osha.gov/SLTC/healthguidelines/hydrogencyanide/recognition.html

So I guess I'd want to move a little bit farther away.

Still waiting to see if anyone posts any actual permit data. Thanks for your the clarification.

milo

You're kidding, right ? HCN is hydrogen cyanide, the gas used in gas chambers, while NH₃ is ammonia . These two gases are extremely toxic . Should you have a temperature inversion in the region, these gases can quickly build up to lethal levels .

Install proper scrubbers to remove them instead of simply discharging them into the atmosphere .

Of course you are right. These are hazardous substances and need to be controlled. However they are normal combustion product of organic compounds and are therefore regulated under ELV conditions in permits issued by EPA et al.

The reason for the original questions is to see where the limits are set in the US and Europe.