Carbon Filter Capacity: Calculate This!
How effective is carbon filtration and how can I know, beforehand, how long my filters will last?
Science and scientists are plagued by calculations; this is both a blessing and a curse. At your fingertips are the tools to get theoretical results with simple, but often long, formulas. Carbon filtration is no different.
Here is the information you need:
* Specific Gravity of Chemical – in grams/mL.
* % Filter Capacity
– The percent by weight in grams that a filter can hold of a given chemical.
* Filter weight – in grams.
* Evaporation Rate of chemical – in mL/min
Here is the simplified calculation:
Theoretical Filter Life (min) =[(total Filter weight (g) x % Filter Capacity) / Specific Gravity (g/mL)] Evaporation rate (mL/min)
Divide the solution by 60 minutes to convert Theoretical Filter life into Hours.
As discussed in the paper “Carbon Filter Capacity: Is my filter half full, or half empty?”
filter life in the real world is approximately 1/3 that of the theoretical or calculated value. Other factors (such as humidity, chemical mixtures and evaporative concentration) can reduce or increase expected filter life (Garrett).
Many companies that offer application chemical assessment services
can perform these calculations for you, if provided the required information. Before relying on carbon filtration, consult with your chemical hygienist or safety officer.
Garrett, Brian. "Carbon Filter Capacity: Is my filter half full, or half empty?" Labconco General Chemistry eNewsletter August 2012. e-Newsletter.
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These enclosures use carbon filters and, in some cases HEPA filters, to protect users from exposure to hazardous fumes. No ducting is required.