In all over a dozen different filter impregnations are used on the filters listed in our chemical listing. The ability of a filter to function efficiently is dependent on a number of factors including Temperature, Humidity, Residence time, Age of filter, Evaporation Rate, Concentration. The temperature of the gas is very important because the higher the temperature, the lower will be the adsorption capacity, especially for a gas with a low boiling point. A relatively high temperature can even generate desorption, with the filter releasing previously adsorbed gas molecules. Generally temperature must be kept below 40 degrees Centigrade.
Relative humidity is an important factor that can affect the efficiency of the filter.
The molecules of gases with low boiling points will be less adsorbed, because the molecules of the water vapor will be absorped in their place, leaving less free surface in the pores for the gas molecules to impact the carbon. Residence time is the time needed by the air to cross the filter, during which it stays in contact with the carbon itself. Or, this is the time during which the molecules of gas can be adsorbed by the pores of the carbon, before leaving it. This time should be as long as possible. To maximize it, the thickness of the filter must be sufficient and the air speed crossing it must be kept to a minimum.