Filters can be hung
using a chain and suitably anchored hooks or may be placed off the floor where
convenient.
How does activated carbon
work?
Picture yourself a sponge with ‘holes or entries’ of different diameter and you
have a fair idea of what activated carbon looks like under a microscope. Based
on the size of the molecules of the compounds to be removed, it is important to
select a type of activated carbon offering just the right amount of pores to
adsorb those molecules.
Adsorption mainly takes place
in the smaller (micro) pores. The amount, in which activated carbon is capable
of binding the molecules of a certain compound, is called adsorption
capacity or affinity. The adsorption capacity is
determined mainly by the molecular structure of the compound: e.g. benzene
(C6H6) is very well adsorbed, while carbon monoxide (CO) is not adsorbed at all.
The larger (meso/macro) pores transport the molecules to
their final destination: the micro pores.
Highly activated carbon may
offer an extremely large total surface area (sometimes over 1.250 m² per gram!)
but have a relatively small amount of micro pores. Such carbons are very
suitable to treat large volumes of saturated gas streams.
Gas streams having lower
concentrations of impurities are best treated with lesser activated carbon
grades offering a more balanced pore size distribution.