Air filters are an essential part of air conditioning and ventilation systems, which not only keep the supply of clean air, but also protects the system itself.
Air Around Us
The polluted air consists of microscopic particles and it is found that in the case of a city, every cubic meter of air contains about 0.7Kg of dirt and in a rural area about 0.35kg.This indicates that the air is to be filtered before using it on air conditioning and ventilation systems.
Selecting the Right Filters
Filters remove the dirts from the air to certain extend. There are three different methods by which we can measure the quantity of dirt removed by a filter.
Method - 1 [by weight ]
This indicates the total weight of dust removed from the air.
Method - 2 [by count ]
This indicates the actual number of dust particles removed from the air.
Method - 3 [ by area ]
This measures the ability of the filter to reduce staining or clogging effect of the dirt from the air.
The air consists of different sizes of dust particles and most of these particles are microscopic. The larger particles count the weight of dust in the air. But in case of smaller particles it needs to measure the staining effect or count. The dust particles by weight count will have two entirely different views of ideas. The distribution of dust particles by weight and size are taken into account when filter efficiency tests are conducted.
The large paritcles of dust in the air are the cause for the weight in the air. The weight test (arrestance) measures the filter's ability to remove the larger particles. If it is of interest in removing heavy atmospheric dusts, one should go for a filter tested by the weight method.
But in the case of clean rooms, where the smaller particles of dust to be taken into account, one has to go for the particle count which will give the filter's effectiveness in removing these type of particles from the air. The area test gives how effective the filter is at reducing the air's ability to stain. It is directly connected to maintenance because staining affects the amount of cleaning and maintenance required.