How Air Filtering systems Work?

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Castellex offers a range of the finest Air Filtering Systems  on the market, but questions we often hear include ‘What exactly are they for?’, ‘How do they work?’, ‘Which System is best for me?’

Good questions, what indeed do Air Filtering Systems do? At the simplest level, the answer is easy – they provide a guaranteed supply of clean filtered air free of dust and contaminants. However, with many types of filter on the market, some better than others for particular needs, the question of what exactly they do becomes ever more important.  Especially so for asthma sufferers and persons with bronchial conditions, hay fever or other allergies, the choice of the correct air filter is critical. For these groups, a good filtering system is going to be a godsend – removing up to 99.9% of particles in the air, the resultant rise in air quality can lead to immediate improvements in health and day to day living.

Depending on the size of the unit, an Air Filtering System can be used for an entire building or for a single room. All in cases though, with the many types of Air Filtering System available, not only in terms of physical size and capacity, but  also type of filter, it is important to know which kind best suits you and what each does.

Of the filtering systems available on the market, the main types are:

HEPA Filters. The HEPA filter is the most commonly seen in households. Using a cloth filter and a fan to circulate air through the system, this type of filter is particularly effective, trapping about 99.9% of particles that are 0.3 microns or larger in size. For asthma sufferers and persons with allergies, this type of air filtration is particularity recommended, significantly reducing airborne allergens such as dust, pollen, animal allergens and mould spores.  It is important to ensure that the filter has a CADR (clean air delivery rate) that matches the size of the room where you plan to use it. If your home or office has central heating, ventilation or air conditioning  systems, these types of filters can be attached to create a “whole house” filtration system, capturing particles without impeding airflow. In all cases,  whether an integrated system or a stand alone Air Filtration System, the filter can be replaced as required.

A HEPA Air Filtration System is very effective, but does use a lot of energy.

Carbon Air Filters.

The second most common type of Air Filtration System, Carbon Air Filters are very effective in removing dust and odours. The carbon air filter contains small pores that are very absorbent and as odour particles pass through the purifier, they attach to the carbon and are absorbed. Please note however that this kind of filter does not work against allergens or micro-organisms and are thus not very effective for people suffering from asthma or allergies.

Ozone filters. Ozone is a reactive oxidant that can destroy some chemicals and bacteria. When it reacts with certain substances in the air, those substances are broken down into materials that are pollutants. While an ozone purifier fights those pollutants, and is also very effective in fighting odours, it does not work against allergens.

Ionic air filters. This type of filtering system ionizes air, causing particles to gain either a positive or negative charge. The ionic air purifier has a collection of plates that contain an opposite charge to that of the air particles and, therefore, attract the particles to the plates.  An ionic air purifier is able to remove very fine particles in the air such as dust particles, even from several feet away, but it does not work on odours or many allergens.


Of these different types of filter, Castellex specializes in HEPA filters and produces a full range of systems suitable for both domestic and commercial application. Recognising the challenge of finding the perfect Air Filtration System for your needs, we remain at your service to offer advice and recommendation. Our goal is to offer you the best possible Air Filtration System to ensure ultimate customer satisfaction.


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Castellex has vast experience in designing and manufacturing NBC (Nuclear Biological Chemical) Air Filtration/ Air supply stations for different applications. It’s widely used across the Globe by military, hospitals, private individuals. No nuclear bunker or survival shelter is completed without the state of the art Castellex NBC air filtration station.
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