Air filtration is very important part of any ventilation system. Every year, level of environmental pollution is growing and the need for quality filtration is also increasing.
|Our company develops projects and installs ventilation systems with maximum degree of air purification for objects such as laboratories, pharmaceutical enterprises, surgical rooms and other facilities where “clean rooms” are needed.|
Classification of air filters is very difficult to understand for a simple person. In this article, we will try to tell you about it as simply and easily as possible.
Classification of air filters
Action effectiveness, air filters are divided into 3 or 4 categories, depending on their filtering abilities.
1. Filters for rough cleaning. Used in rooms with low requirements for clean air or as one of the stages of air purification – air pre-purification. Such filters capture large particles with a size of 10 microns.
|! Μicron is a measure of small distances length, 1 micron = 0.001 mm = 0.0001 sm = 0.000001 m. For example, the erythrocyte diameter is 7 microns, atmospheric particles mostly have a diameter from 0.1 to 5 microns.|
1. Fine air purification filters. They are used practically in all areas of industry or in everyday life, as a rule they are installed as a second stage of air purification. Different particles larger than 1 micron are trapped.
2. Absolute air purification filters or HEPA filters. Such filters are used to create “clean rooms” in pharmaceutical companies, operating companies, electronics industry and other areas where a high level of filtration and particle size removes from 0.3 micron is required. Until now, these filters were the most effective filters.
3. ULTRA filters – are the fourth kind of filters which has not become a separate type of filtration yet, someone still divides all filters into three types, classifying Ultra filters as absolute air purification class, and somebody allocates ultrahigh-purity filters to a separate class. These are final air purification filters and are used exclusively in specialized rooms in which the most effective air filtration is needed.
Filters marking depending on filtration class
Each of the above categories has several classes of cleaning. Which are called differently depending on standard.
Table 1 shows marking of filters, depending on the class of their effectiveness.
|Level of cleaning||Type of cleaning||Cleaning efficiency, %|
|DIN 24184 DIN 24185||State standard Р 51251-99||EN 779||EN 1822||State standard Р 51251-99||EN 1822|
|According to test methods*|
|High efficiency (НЕРА)||H10||H10||85|
|Table 1. Classification and marking of air filters. Note: EN779 and EN1882 are Russian standards for raw, fine and ultra fine filters, respectively.|