Carbon Filter Capacity: Is My Filter Half Full, Or Half Empty?

By Brian Garrett, LEED Green Associate & Product Specialist, Labconco Corporation

Activated and Impregnated Carbon materials can be effective at filtering contaminants out of liquid or air streams. This process is called adsorption. Like any filter in today’s laboratory, significant energy is spent replacing used carbon filters. Is it then critical to understand how long your filters should last?

Filter manufacturers typically have dedicated catalog numbers for filters, and those filters have standard sizes. A filter’s capacity is often expressed as a volume for a specific chemical that filter has the capacity to hold. (For example, a filter is rated to hold 250mLs of xylene, then the theoretical volume capacity of that filter for xylene is 250mLs.)

Carbon and Filter manufacturers often choose to express a filter’s capacity for any given chemical by providing a percentage. This is a “capacity by weight” ratio that can be used to calculate volume based on filter size. (For example, a carbon filter has a filter weight capacity for xylene of 27.6%. If you had 100 grams of carbon, you could theoretically trap 27.6 grams of xylene.)