For laboratory filters the machines may be as small as 50 cm width. The filter papers may also be treated with reagents or impregnation to get the right properties.
The main application for air filters are combustion air to engines.
For high quality filters, dissolving pulp and mercerised pulp are used.
Most filter papers are made on small paper machines.
This grade of filter paper requires more filtration time than Grade 1 filter paper.
This filter paper is used for monitoring specific contaminants in the atmosphere and soil testing.Generally, filter papers are used with laboratory techniques such as gravity or vacuum filtration.Qualitative filter paper is used in qualitative analytical techniques to determine materials.Chromatography is a method chemists use to separate compounds.This type of filter paper has specific water flow rate and absorption speed to maximize the result of paper chromatography.There are different grades of qualitative filter paper according to different pore size.There are total 13 different grades of qualitative filter paper.The largest pore size is grade 4; the smallest pore size is grade 602 h; the most commonly used grades are grade 1 to grade 4.Grade 1 qualitative filter paper has the pore size of 11 μm.The filter papers are transformed into filter cartridges, which then is fitted to a holder.The construction of the cartridges mostly requires that the paper is stiff enough to be self-supporting.