Feature
Freudenberg Filtration
The composition of air : Size comparison of solid and gaseous substances in the ambient air .
Freudenberg Filtration you have to ask yourself is how many systems conform to the regulations in this regard ? “ Engineers design based on criteria and requirements inside of a building which may not require such intense air filtration or which is just not necessary for the particular application ,” says Hennie Verster , marketing manager at Freudenberg Filtration .
Part of the air filtration design process is also the establishment of positive or negative room pressures , as in some instances you want to avoid certain particles entering a space but then you may not want particles to leave a space – this is particularly important in testing laboratories , medical facilities and even production lines where cross contamination can occur between different products in powder forms .
It is important to then understand the types of particles ‘ in the air ’ that are required to ( or you wish to ) be filtered out , which include natural sources as well as sources of human origin ( not limited to ):
NATURAL SOURCES – ORGANIC AND INORGANIC – GENERALLY 1 – 10 μm
• Organic debris such as leaves or seeds
• Pollens
• Fungal spores
An example of an air handling unit ( AHU ) indicating , pocket filter , cassette filter and HEPA filter .
• Hair and skin cells
• Bacteria
• Viruses
• Sandstorms
• Landscape fires
• Volcanic activity
• Erosion
• Salts
MAN-MADE SOURCES – OUTDOOR AND INDOOR – GENERALLY LESS THAN 1 μm
• Combusion process in engines
• Domestic heating
• Tyre fumes
• Air traffic / dumped fuels
• Gases produced by industrial processes
• Agricultural pesticides
• Clothing and carpet particles
• Mineral fibres
• Emissions from laser printing machines
• Cigarette smoke , candles , incense
• Cleaning products
Again , the starting point of your design would come down to the application and desired outcome . The lists above indicate the types of particles that can be found in an ‘ air sample ’ to be considered in air quality , however another particular element in filtration in the HVAC sector is the protection of components that may be as important on a site where corrosion is a factor , where sands can penetrate mechanical units or dust can cause short circuiting of electronic components .
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www . hvacronline . co . za RACA Journal I November 2020 13