Air Filter Ratings
There are many types of air filters, but any filter that is labeled "HEPA" has a very specific rating. The HEPA standard states that a HEPA air filter must trap 99.97% of all airborne contaminants that are 0.3 microns.
This means that for every 10,000 air particles that are 0.3 microns, the HEPA filter will only allow 3 of them to pass through.
How Big is a Micron?
A micron is 1 millionth of a meter, or about 0.00003937 inches, which means there are 25,400 microns in an inch. This dot (.) on your computer screen is about 615 microns.
The human eye can see particles as small as 10 microns, and an optical microscope allows us to see things as small as 0.1 micron. Electron microscopes allow us to see things as small as 0.001 microns.
HEPA air filters are the most efficient type of air filter because they can trap most air particles including bacteria and viruses.
Other Types of Air Filters
HEPA filters are classed as a mechanical air filter. Other types of air filters include Electronic or Electrostatic Air Cleaners and Gas-phase Absorption Air Filters. The American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) has come up with a rating system for each type of air filter. This rating system is called Minimum Efficiency Reporting Values (MERV) and most air filter manufacturers now label their products with a MERV rating.
Typical disposable air filters are rated between MERV 1 and MERV 10, with the higher ratings indicating a more efficient air filter.
The HEPA standard exceeds the MERV specifications because they are the only mechanical air filter with an efficiency of 99.97% at 0.3 microns. This makes them at least 50% more effective than other types of mechanical air filters.
Comments
pragnesh
10 Mar 2007, 05:40
Really on this site you have mentioned very good information, I really
appriciate your efforts.
My question is --- I want to know the gradation of filter because in
pharmaceutical industries people are used to indentify the filter by grade
like H 12, H 13, EU 12
I am requesting you please inform me regarding this grade and If possible
than send me this grade with micron size
Thanks
Pragnesh Patel.
Mark
10 Mar 2007, 11:04
The H12 rating is for a filter with a 99.5% efficiency rating and H13 is
rated at 99.95% efficiency with 0.05% penetration. The local value of H13
is 99.75% efficiency - so HEPA filters are comparable to a H14 rating which
has a local value of 99.975% efficiency.
Labade Ganesh Sitaram
05 Apr 2007, 11:33
Dear Sir,
I requisted You pl. send EU standered for filter efficency
KIRAN kOTASTHANE
28 Apr 2007, 09:05
I requisted You pl. send EU standered for filter efficency alog with the
comparison with other stansards
purvi
05 Jan 2008, 03:17
Dear Sir,
I requisted You pl. send EU standered for filter efficency
requisted You pl. send EU standered for filter efficency alog with the
comparison with other stansards
also let me know whether hepa can be of efficiency below .3 micron
Indulal Acharya
08 Feb 2008, 02:11
Dear Sir,
I would like to know how to fix the size of hepa filters (i.e. 400 m3/hr.)
Please let us have size calculation for suitable filters for Hepa by less
pressure drop.
B. Giridhar
01 Mar 2008, 13:27
Pls define me the micron size w.r.to EU filter grade
umesh
09 Mar 2008, 06:22
Please let me know the acceptance criteria of hepa filter when dop test is
carried out at the hepa filter media,bonding and gasket for the hepa filter
with the effeciency of 99.997%.And pharma regulatory comments on this part.
umesh
09 Mar 2008, 06:23
please let me know the maximum velocity by which air pass through the hepa
media for one square feet of area
C Karuppusamy
14 Apr 2008, 04:34
Please send EU standered for filter efficency alog with the comparison with
other stansards.
please let me know the maximum velocity by which air can pass through the
HEPA Filter.
Mr.yotsak
03 May 2008, 09:54
Request quotation for HEPA filter
Spec.
size ; 600mm*600mm*295mm(or 300)
Casing ; SUS304
Efficeincy ; >99.997% at 0.3 micron
Flow rate ; >4 Nm3/min
Seal ; general
Pre-filter
size 600mm*600mm*50mm
General spec in market
SHYAM
07 Jun 2008, 13:34
Pls define me the micron size w.r.to EU filter grade
Abhijit K
16 Jun 2008, 06:25
Sir,
I would like to know about EU filter ratings, their respective filtration
efficiancy and the max allowable air velocity across the media. (I am not
concern about filter bax face velocity) Kindly suggest.
Thanks n Regards,
AMK
Paul
16 Jun 2008, 07:27
A table of filtration values can be found here:
http://www.filtration-engineering.co.uk/air_filter_testing.htm
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