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HEPA Filters
Hepa filters are the most important component in the CRUMA laminar flow cabinets (CLFC), which have a wide range of applications in fields such as microelectronics, scientific and health research. Also known as “absolute” filters, they were developed during World War II to remove radioactive particles from the air in the nuclear industry. Since then, they have undergone continual advances to satisfy the ever-increasing demand for smaller particles.
A conventional HEPA filter consists of a continuous special fibreglass film pleated in a V with aluminium separators corrugated between the pleats. The technique with which the pleats are arranged is what makes these filters such efficient separators. The HEPA filters employed by CRUMA are EN-1822 Class H-14, with a minimum DOP test efficiency of 99.995% for 0.3-mm particles. The largest part of the CLFC filtering component are Class H-14 “minipleat” filters of the most advanced construction embedded in a rigid frame with a special polyurethane compound.
Thermoplastic displacers are also employed as efficient separators in the HEPA group. The next most efficient filter is the U-15, which is in the ULPA class filters (ultra efficient), used in very special applications. High-quality filters such as those in the 870-FL and 670-FL are tested to determine their efficiency with submicron particles as well as pressure drop (flow resistance). The most common method of finding efficiency is with the DOP test (as established in the EN-1822 Standard, as complied with by the 870-FL and 670-FL filters).
Classification of air purity
The classification of air purity that defines how clean the air is, in terms of the number of particles of a certain size by unit of volume that are found in it, has been developed and included in various international standards. US Federal Standard 209 was the first and, afterward, others such as the Australian AS1386 and the British BS5295 Standards were published up to the appearance of the most recent in 1999, for national and European application, EN-ISO-14644-1 which establishes the following classes:
This table shows the maximum concentration per m3 of particles with the same size or larger than given in the header of each column.
ISO 5 class air purity is precisely what the HEPA class H-14 (EN-1822) filter in CRUMA models 870-FL and 670-FL laminar flow cabinets provides.
air filtration. laminar flow
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Airborne contaminants
Our environment contains large amounts of both gaseous and solid (particles) contaminants. The "clean air" systems application, based on laminar air flow, and contaminant containment technologies are essential to approach the issue of particle contamination. Gaseous contaminants can be controlled by the use of ductless fume hoods with activated carbon filters, systems also manufactured and marketed by CRUMA.
Many critical applications in the field of science, industry or health require such environments as clean rooms, that are particle and/or germ-free. An adult wearing normal clothing emits around 9 million particles per minute ranging in size between 0.5 and 100 µm. People are therefore the greatest source of contamination in clean rooms, and are responsible for around 80% of particles in suspension.
Our environment contains large amounts of both gaseous and solid (particles) contaminants. The "clean air" systems application, based on laminar air flow, and contaminant containment technologies are essential to approach the issue of particle contamination. Gaseous contaminants can be controlled by the use of ductless fume hoods with activated carbon filters, systems also manufactured and marketed by CRUMA.
Many critical applications in the field of science, industry or health require such environments as clean rooms, that are particle and/or germ-free. An adult wearing normal clothing emits around 9 million particles per minute ranging in size between 0.5 and 100 µm. People are therefore the greatest source of contamination in clean rooms, and are responsible for around 80% of particles in suspension.
HEPA Filters
Hepa filters are the most important component in the CRUMA laminar flow cabinets (CLFC), which have a wide range of applications in fields such as microelectronics, scientific and health research. Also known as “absolute” filters, they were developed during World War II to remove radioactive particles from the air in the nuclear industry. Since then, they have undergone continual advances to satisfy the ever-increasing demand for smaller particles.
A conventional HEPA filter consists of a continuous special fibreglass film pleated in a V with aluminium separators corrugated between the pleats. The technique with which the pleats are arranged is what makes these filters such efficient separators. The HEPA filters employed by CRUMA are EN-1822 Class H-14, with a minimum DOP test efficiency of 99.995% for 0.3-mm particles. The largest part of the CLFC filtering component are Class H-14 “minipleat” filters of the most advanced construction embedded in a rigid frame with a special polyurethane compound.
Thermoplastic displacers are also employed as efficient separators in the HEPA group. The next most efficient filter is the U-15, which is in the ULPA class filters (ultra efficient), used in very special applications. High-quality filters such as those in the 870-FL and 670-FL are tested to determine their efficiency with submicron particles as well as pressure drop (flow resistance). The most common method of finding efficiency is with the DOP test (as established in the EN-1822 Standard, as complied with by the 870-FL and 670-FL filters).
Classification of air purity
The classification of air purity that defines how clean the air is, in terms of the number of particles of a certain size by unit of volume that are found in it, has been developed and included in various international standards. US Federal Standard 209 was the first and, afterward, others such as the Australian AS1386 and the British BS5295 Standards were published up to the appearance of the most recent in 1999, for national and European application, EN-ISO-14644-1 which establishes the following classes:
| ISO Classification | 0.1µm | 0.2µm | 0.3µm | 0.5µm | 1µm | 1µm |
| ISO Class 1 | 10 | 2 | 0 | 0 | 0 | 0 |
| ISO Class 2 | 100 | 24 | 10 | 4 | 0 | 0 |
| ISO Class 3 | 1.000 | 237 | 102 | 35 | 8 | 0 |
| ISO Class 4 | 10.000 | 2.370 | 1.020 | 352 | 83 | 0 |
| ISO Class 5 | 100.000 | 23.700 | 10.200 | 3.520 | 832 | 29 |
| ISO Class 6 | 1.000.000 | 237.000 | 102.000 | 35.200 | 8.320 | 293 |
| ISO Class 7 | 10.000.000 | 2.370.000 | 1.020.000 | 352.000 | 83.200 | 2.930 |
| ISO Class 8 | 100.000.000 | 23.700.000 | 10.200.000 | 3.520.000 | 832.000 | 29.300 |
| ISO Class 9 | 1.000.000.000 | 237.000.000 | 102.000.000 | 35.200.000 | 8.320.000 | 293.000 |
This table shows the maximum concentration per m3 of particles with the same size or larger than given in the header of each column.
ISO 5 class air purity is precisely what the HEPA class H-14 (EN-1822) filter in CRUMA models 870-FL and 670-FL laminar flow cabinets provides.
