Air Purifier

You can easily obtain air purifier of HEPA, ionizer or activated carbon type. But what does these air conditioning system offer you in return? Continue reading...

By Simon Thompson

An air purifying equipment is a device which removes contaminants including dust, pollen, pet dander, mould spores, dust mite faeces (which can act as allergens) and smoke particles from the air.

These equipment are particularly beneficial you are allergic (especially if you have hay fever), asthmatics, and at reducing tobacco smoke in air.

Air purifying equipment are used primarily for the following purposes:

  • Removing odours, e.g. from pets, cooking, tobacco,

  • Removing mould, mildew and pollen,

  • Removing chemical gases and paint fumes,

  • Removing bacteria, viruses and fungi,

  • Removing dust and smoke particles,

  • Returning clean air,

  • Ionising the air you breathe,

It will also reduce the need for frequent household cleaning and very energy efficient.

There are different processes with varying degrees of effectiveness for purifying your air.

Different processes can remove different contaminants, so there can be an advantage in using more than one process for your equipment.

The most common air purifying processes are:

  1. Filter based (normally HEPA) system.

    These trap airborne particles by size exclusion. Air is forced through a filter and particles are physically captured by the filter.

    HEPA filter specification requires removal of at least 99.97% of 0.3 micrometers.

    It is effective down to 0.01 micrometers in many cases, but become less effective for particles smaller than 0.01 micrometer.

    HEPA purifiers which filter all the air going into a clean room must be arranged so that no air bypasses the HEPA filter.

    In dusty environments, a HEPA filter may be fitted in conjunction with an easily cleaned conventional filter (pre filter), which removes coarser impurities such that the HEPA filter does not need to be changed or cleaned frequently.

  2. Activated carbon filtration.

    Activated carbon is a highly porous material that can absorb volatile chemicals on a molecular basis, but does not remove larger particles.

    Activated carbon is a process of changing contaminants from gaseous to solid phase. Activated carbon can be used at room temperature and has a long history of commercial use.

    It is normally used in conjunction with other air purifier, especially with HEPA.

  3. Ionizer purifiers.

    Uses charged electrical surfaces or needles to generate electrically charged ions. Ions attach to airborne particles which are then electrostatically attracted to a charged collector plate.

    This mechanism produces trace amounts of ozone and other oxidants as by product. Most ionizers produce less than 0.05 ppm of ozone - an industrial safety standard.

    There are two major subdivisions for ionizers, namely fan-less ionizer and fan based ionizer.

    Fan-less ionizers are noiseless and use little power, but are less efficient at air purification.

    Fan based ionizers clean and distribute air much quicker. Permanently mounted home and industrial ionizer purifiers are called electrostatic precipitators.

Factors to consider when purchasing an air puriying equipment

Frequency of filter replacement and electrical consumption are the only operation costs for any purifier.

There are many different types of filters. Some can be cleaned by water, by hand or by vacuum cleaner, while others need to be replaced every few months or years.

Some are certified as energy star and are energy efficient.

Other factors to consider when purchasing the equipment are,

  • coverage area,

  • Air Changes Per Hour, which indicates how frequently the equipment can exchange all the air in a given room,

  • Clean Air Delivery Rate, which determines how well air has been purified,

  • energy usage

  • and the cost of the replacement filters

Simon Thompson,
Located in Stockport, UK,© Copyright is owned by the author

His site provides information and products on air purifying equipment and air conditioning

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