What is a Cleanroom?
Cleanroom Overview | Cleanroom
Air Flow Principles | Cleanroom
Classifictations | US Fed STD 209E
Cleanroom Standards
BS 5295 Cleanroom Standards | ISO
14644-1 Cleanroom Standards
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Custom Designed Cleanroom
Custom
Designed Cleanroom
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Cleanroom With Custom Door Option
Cleanroom
With Custom Door Option
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Custom Control Panel For Cleanroom Manufacture
Custom
Control Panel For Cleanroom Manufacture
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Blower For Cleanroom
Custom
Control Panel For Cleanroom Manufacture
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Typically used in manufacturing or scientific research,
a cleanroom is a controlled environment that has a low
level of pollutants such as dust, airborne microbes,
aerosol particles, and chemical vapors. To be exact,
a cleanroom has a controlled level of contamination that
is specified by the number of particles per cubic meter
at a specified particle size. The ambient air outside
in a typical city environment contains 35,000,000 particles
per cubic meter, 0.5 mm and larger in diameter, corresponding
to an ISO 9 cleanroom which is at the lowest level of
cleanroom standards.
Cleanroom Overview
Cleanrooms can be a variety of sizes. Entire manufacturing
facilities can be contained within a cleanroom with the
area covering thousands of square feet. They are used
extensively in semiconductor manufacturing, biotechnology,
the life sciences, pharmaceutical, semiconductor, electronic,
optics, military/ aerospace, medical, pharmacy, FDA validatable,
manufacturing/industrial, packaging industries, and other
fields that are very sensitive to environmental contamination.
Cleanroom air coming from an outside source is filtered
to eliminate dust, and the inside air is recirculated
constantly through HEPA air filters and/or ultra-low
particulate air (ULPA) filters that remove containments
produced from within the cleanroom.
Personnel enter and leave cleanrooms through airlocks
(sometimes including an air shower stage), and wear protective
clothing such as hats, face masks, gloves, boots and
coveralls.
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The equipment inside a cleanroom is designed to generate
minimal air contamination. There are even specialized
mops and buckets. Cleanroom furniture is also designed
to produce a minimum of particles and to be easy to clean.
Since common materials such as paper, pencils, and fabrics
made from natural fibers are often excluded, there are
alternatives available. Cleanrooms are not a sterile
environment (i.e., free of uncontrolled microbes). The
attention is to controlling airborne particles. Particle
levels are tested using a particle counter.
Some cleanrooms are kept at a positive pressure so that
if any leaks are present, air leaks out of the chamber
instead of unfiltered air coming in. Some cleanroom HVAC
systems control the humidity to low levels so extra equipment
called ionizers are necessary to prevent electrostatic
discharge (ESD) problems.
Cleanroom clothing is used to prevent substances from
being released off the wearer's body from contaminating
the environment. The cleanroom clothing itself must not
release particles or fibres to prevent contamination
of the environment by personnel. This type of personnel
contamination can degrade product performance in the
semiconductor and pharmaceutical industries and it can
cause cross-infection between medical staff and patients
in the health care industry, for example.
Cleanroom clothing performance is also an important
issue. Penetration through fabrics, seams and fasteners,
and leakage between the clothing and the body must be
prevented. Leakage can occur at any point where there
is a gap between the wearer's body and the equipment
and/or clothing. Face mask performance can also be limited
by leakage of this type. Clothing penetration can also
occur from pressure differences between the inside and
outside of the garments which result from body movements.
Air flow into cleanroom garments can contaminate the
body, and airflow out of the garment can contaminate
the cleanroom environment.
Cleanroom garments include boots, shoes, aprons, beard
covers, bouffant caps, coveralls, face masks, frocks/lab
coats, gowns, glove and finger cots, hairnets, hoods,
sleeves and shoe covers. The type of cleanroom garments
used should reflect the cleanroom and product specifications.
Low-level cleanrooms may only require special shoes having
completely smooth soles that do not track in dust or
dirt. However, shoe bottoms must not create slipping
hazards since safety always takes precedence. A cleanroom
suite is usually required for entering a cleanroom. Class
10,000 cleanrooms may use simple smocks, head covers,
and booties. For Class 10 cleanrooms, careful gown wearing
procedures with a zipped cover all, boots, gloves and
complete respirator enclosure are required.
In other cleanrooms where the air contamination standards
are less rigorous, the entrance to the cleanroom may
not have an air shower. There is an anteroom, which is
also known as a gray room, where special suits must be
put on allowing a person to directly walk into the cleanroom.
Rather than using fully classified cleanrooms, some facilities
use some cleanroom practices together to maintain their
cleanliness requirements.
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Cleanroom Air Flow Principles
Cleanrooms maintain particulate-free air through the
use of either HEPA or ULPA filters employing laminar
or turbulent air flow principles. Laminar, or unidirectional,
air flow systems direct filtered air downward in a constant
stream towards filters located on walls near the cleanroom
floor. Laminar air flow systems are typically employed
across 80% of a cleanroom ceiling to maintain constant
air processing. Stainless steel or other non-shed materials
are used to construct laminar air flow filters and hoods
to prevent excess particles entering the air. Turbulent,
or non-unidirectional, air flow uses both laminar air
flow hoods and non-specific velocity filters to keep
air in a cleanroom in constant motion, although not all
in the same direction. The rough air seeks to trap particles
that may be in the air and drive them towards the floor,
where they enter filters and leave the cleanroom environment.
Cleanroom Classifications
Cleanrooms are classified by how clean the air is. In
Federal Standard 209 (A to D) of the USA, the number
of particles equal to and greater than 0.5mm is measured
in one cubic foot of air, and this count is used to classify
the cleanroom. This metric nomenclature is also accepted
in the most recent 209E version of the Standard. Federal
Standard 209E is used domestically. The newer standard
is TC 209 from the International Standards Organization.
Both standards classify a cleanroom by the number of
particles found in the laboratory's air. The cleanroom
classification standards FS 209E and ISO 14644-1 require
specific particle count measurements and calculations
to classify the cleanliness level of a cleanroom or clean
area. In the UK, British Standard 5295 is used to classify
cleanrooms. This standard is about to be superseded by
BS EN ISO 14644-1.
Cleanrooms are classified according to the number and
size of particles permitted per volume of air. Large
numbers like "class 100" or "class 1000" refer to FED_STD-209E,
and denote the number of particles of size 0.5 mm or
larger permitted per cubic foot of air. The standard
also allows interpolation, so it is possible to describe
e.g. "class 2000."
Small numbers refer to ISO 14644-1 standards, which
specify the decimal logarithm of the number of particles
0.1 µm or larger permitted per cubic metre of air.
So, for example, an ISO class 5 cleanroom has at most
105 = 100,000 particles per m³.
Both FS 209E and ISO 14644-1 assume log-log relationships
between particle size and particle concentration. For
that reason, there is no such thing as zero particle
concentration. Ordinary room air is approximately class
1,000,000 or ISO 9.
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US FED STD 209E Cleanroom Standards
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BS 5295 Cleanroom Standards
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ISO 14644-1 Cleanroom Standards
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