THE AIR WE BREATHE
Air is a mixture of gases composed of approximately 21% oxygen, 78% nitrogen, 1% argon, and traces of other gases. The air we breathe also includes particulate material and gases generated by nature, by man, and by industrial processes as seen in the Figure.
EFFECT OF MEASURING METHOD
Work done under the sponsorship of ASHRAE and private organizations such as filter manufacturers showed that the percentage distribution of particle sizes in the atmosphere depended significantly on the method of measurement.
MECHANISM OF AIR FILTER
The total efficiency of a filter is the sum of the four filtration effects. Under certain conditions, total efficiency will have a certain minimum value
The use of HEPA filters used in air conditioning systems in clean rooms is increasing day by day in pharma, food and hospitals.
Airborne pollution sources are various which can be from natural sources like volcanos, thermal sources, pollens, sand storms and from industrial life like factories, automobile emissions, jet fuels, garbage dumps etc.
HEPA/ULPA FILTER TEST SYSTEMS
CEN standards in Europe, IEST and MIL standards in the US are used for HEPA and ULPA filters. HEPA / ULPA filters are individually tested and certified in accordance with both standards in Ulpatek.
ISO 16890 standard is the new standard that has replaced the EN779: 2012. This standard covers Coarse filters (Class G), Medium filters (Class M) and Fine filters (Class F) and eliminate the insufficient points of the old standard.
Efficient air filters (EPA), high efficiency air filters (HEPA) and ultra low penetration air filters (ULPA) are classified and tested according to EN 1822 standard for ventilation and air conditioning systems such as cleanroom applications.
EN ISO 14644-1
ISO 14644-1 defines the classification of air cleanliness in cleanrooms and associated controlled environments exclusively in terms of concentration of airborne particles. Only particle populations having cumulative distributions based on threshold (lower limit) particle sizes ranging from 0,1 μm to 5 μm are considered for classification purposes.