About Cleanroom
according to IEC 61340-5-1/5-2
This is the most complete information about cleanrooms on the internet. Below you will learn:
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A cleanroom is a specially designed enclosed space where airborne particulates have been limited or removed by a highly sophisticated filtration system. They are used by industries that require a highly controlled and monitored environment for the production of delicate instruments or medical supplies and medicines. For a room to be classified as a cleanroom, it has to meet a precise set of international standards regarding the number of microns per cubic foot.
According to ISO 14644-1, a cleanroom is: “… room within which the number concentration of airborne particles is controlled and classified, Part 1: Classification of air cleanliness by particle concentration.
The standards regarding a cleanroom are measured in micrometers. The image on the right compares a hair follicle to a 90 µm particle of fine sand. The maximum particulate content per cubic meter for a classification ISO 1 cleanroom is 5 µm. |
Duct Supply and Duct Return (from spetec.com) |
There are three methods used to ensure that a Cleanroom can maintain its classification.
The primary method of ensuring that the air in a Cleanroom is at the appropriate cleanliness level is the installation of an air filtration system
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Here is a description of each air flow system: |
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BS 5295 (British Standard) Air is ducted directly into the cleanroom and ducted directly out. Duct Supply and Duct Return (from spetec.com) |
Ducted Supply and Open Return The ducted supply and open return air is a cost-effective and efficient method of air delivery.
Duct Supply and Open Return (from spetec.com) |
Uni-directional: Unidirectional, or laminar, airflow systems force air in one direction. It has controlled airflow with steady air velocity from the laminar airflow hoods that direct air downward. In most Cleanrooms, the downward airflow pushes particulates out to prevent them from landing on surfaces. With a laminar system, air is pushed through filters that catch microscopic particles. |
Laminar Air Flow System (from www.environmental-expert.com) |
Cleanroom Air Filters The filtration system for a cleanroom is its most important component, since it is what keeps it clean. Cleanrooms can have single or multiple filters depending on their design and ISO classification. Most systems have filters located in the ceiling. Air travels downward from the ceiling to the floor and exits through ducts in the floor. |
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Pre-Filters: Pre-filter filters the air before it reaches the HEPA or ultra-low particulate air (ULPA) filters. |
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ULPA-Filters: ULPA filters are very similar to HEPA filters but are far more efficient. |
ULPA Filter(from americanfiltration.com) |
HEPA-Filters: HEPA-filter filters out 99.99% of particles at 0.3 µm.
The difficulty in capturing microscopic particles is their flight path. Unlike blown dust that moves in the direction of the wind, the Brownian motion of microscopic particles causes them to travel erratically. The multiple directions of the fibers of a HEPA filter are able to capture and trap microscopic particles. The image below shows the placement of HEPA or ULPA filters in a unidirectional system.
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Industrial Clean Room HEPA Air Filter (from airshowertunnel) The fibers of a HEPA filter are randomly arranged to form a dense mat. A fibrous filter's media as seen through an electron microscope.(image credit: ECAT) |
The classification of a cleanroom is determined by the amount of particulate matter (PM), a descriptor for particles and liquids in the air, it has per cubic meter. The most accepted classification method for cleanroom is the International Organization of Standards (ISO), an international standards setting group that has representatives ISO 14698 establishes the methodology and procedures for the elimination of biocontaminants from cleanroom. Cleanroom classifications start with grade ISO 1, for extremely clean, and go to ISO 9, satisfactorily clean, which is normal room air.
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ISO Cleanroom Classifications (from cleanroombuilt.com) |
The United States classification system for cleanrooms was Federal Standard 209E published by the Institute of Environmental Sciences and Technology (IEST) in 1963, which can be seen in the chart below. The IEST used a classification system that ran from Class 1, an ISO 3 class, to Class 100,000, an ISO 8 classification. Though several countries still use the IEST system, it was formally retired in 2001 as being obsolete. |
(from cleanroombuilt.com) |
International Classification Systems Though ISO standards have been widely accepted and serve as a guide for most nations, individual countries have developed their own systems. EU GMP EU GMP classifications are used as a method of inspection for all phases of the production process. |
EU GMP Guidelines for Cleanrooms (image from european pharmaceutical review) |
BS 5295 BS 5295 has ten classes of standards for cleanliness as seen in the chart below. Each classification has a range of particulate counts for a more specific definition of particle size. |
BS 5295 Classifications (from cleanroomclassification.blogspot.com) |
USP 800 USP 800 is a set of published standards for the handling of hazardous drugs (HD), which went into effect in December of 2019. For Cleanrooms, USP 800 requires negative pressure, external ventilation, and air changes of 12 ACH per hour for drug storage areas. To meet the need for compliance with USP 800, ionization and polarization are used to collect particles, viruses, bacteria, volatile organic compounds, and gases. |
Though there are many different construction methods for cleanrooms, all manufacturers have to follow the guidelines of ISO 14644-1, ISO 14698-1,
Each of these factors are described below: |
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Surfaces Cleanroom surfaces are smooth and impervious and will not peel, flake, corrode, create dust, or have places for microorganism to grow. They must be able to be easily cleaned and accessible. In microelectronic and semiconductor Cleanrooms, surfaces are required to be smooth and free of potential ESDs. Surface materials are shatter, dent, and crack resistant as well as crease repellent. Floors in Cleanrooms are either epoxy resin or PVC. Resin floors are used where there is high mechanical loads since resin has high resistance and strength. The most common use of resin floors is in rooms that have water or high humidity. PVC floors are more economical and are laid out in tiles. They are used in low little traffic areas where there aren’t heavy loads. |
Epoxy Resin Flooring (from cleanroomtechnology.com) |
Equipment: Cleanroom equipment is manufactured from easy-to-clean materials such as stainless steel, polycarbonate, or plastic laminates. The type of equipment used in a cleanroom is anything that is not attached to the walls or floor, which includes a wide range of items from simple hand tools to showers and pass throughs. Below are some of the types of equipment that are commonly found in a Cleanroom: Add a description of the image here
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Air Control Systems: Cleanrooms require a great deal of air and need to have the temperature and humidity controlled. Air control system is the most essential part of a cleanroom. When planning a cleanroom, it is necessary to study how much exfiltration there is, or the amount of air that will escape the room. A common exit path is through doors. The amount of exfiltrating through a door is determined by the size of the door, pressure across the floor, and how well the door is sealed. In order to compensate for exfiltration, the airflow needs to be balanced where the amount exfiltrating matches the amount of infiltrating. The diagram below shows the exfiltration and infiltration or the air exchange rate of a unidirectional air flow system, where 1 represents the infiltration and 2 is exfiltration. |
Epoxy Resin Flooring (from cleanroomtechnology.com) |
Number of personnel: The major source of cleanroom contamination is from the people who work in them According to academic studies, only select and trained personnel should be allowed in a cleanroom. |
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Lighting: Cleanroom lighting is designed to meet specialized environmental requirements. Unlike the air control system, lighting represents 1% of the total cost of operating a cleanroom. As with all cleanroom factors, the air control system takes preeminence making the planning of lighting demanding, requiring careful planning and design. For energy efficiency, cleanrooms use LER lamps, which are easy to maintain and have a long life. |
100W Low Profile Cleanroom LED Lighting (from larsonelectronics.com) |
Other types of lighting are incandescent, high intensity, and LED. In most cleanrooms, ballasts and lamp holders are easily removed to avoid disturbing cleanroom conditions. Example of a well-lit cleanroom where a technician is testing the particle count. |
Well Lit Cleanroom (image from Production Automation Corporation) |
A recent development is automated lighting that uses a passive infrared sensor motion detector to avoid waste of energy, In the design phase of a cleanroom, engineers determine the necessary lux level, unit of illuminance, that is necessary. |
Lux Table (from cleanroomtechnology.com) |
Doors: Cleanroom doors are responsible for keeping the room sealed from external contaminants and maintaining the controlled environment.
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Single and Double Cleanroom Doors (from cleaningroomsystem.com) |
Viewing Panels: The purpose of viewing panels is for operators to work more efficiently and have visual contact. Viewing panels must be flush to both sides of the wall, shatter proof, with a drying agent in the void between the glass panels, and fire resistant. The visual display below has examples of various types of view panels. |
Viewing Panels (from moduclean.com) |
Low Humidity: The relative humidity (RH) for a cleanroom should be between 30 to 60% at a balanced level to protect against overly moist or dry conditions. Air conditioning lowers the surface temperature in a cleanroom, while the desiccant process absorbs moisture in the air. |
Desiccant Dehumidification Filter (from munsters.com) |
Different Levels of Cleanrooms The level of a cleanroom is determined by its air. All cleanrooms are built the same with airtight walls, doors, windows, and very clean air. Lower levels of cleanrooms such as ISO level 9 to ISO level 6, cleanliness is based on the amount of air exchanged each hour, There are three different states in the determination of the level of a cleanroom: as built, at rest, and operational. The change in level takes a significant up or down move when it is in full operation. The image below is of a stage three of a fully operational high bay cleanroom for NASA |
NASA’s MMS Team Assembling Final Observatory (from nasa.gov) |
The biggest problem with Cleanrooms is people since they carry contaminants and microorganisms on their skin. The image below is of clothing for a strictly monitored Cleanroom. The ISO class of a Cleanroom determines the type of clothing that personnel are required to wear. Listed below are the ISO 14664 clothing requirements for Cleanrooms.
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Cleanroom Clothing (from www.ortner-group.com) |
Cleanroom Clothing Factors:
Disposable clothing is the most common option for Cleanroom clothing, which is disposed of in designated bins. |
Cleanroom Disposable Coverings (from creativemindsofours.blogspot.com) |
Rules for Cleanroom Personnel
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The definition of the types of designs for cleanrooms begins with the method of ventilation, Turbulent Ventilated Cleanroom (from spaceindustries.co.uk) Unidirectional Flow Cleanroom (from spaceindustries.co.uk)
Beyond the types of airflow is kinds of construction, which can be modular or conventional, stick built. |
Hardwall Cleanrooms Hardwall Cleanrooms are modular cleanrooms with aluminum posts and rigid wall construction for increased air pressure. Vertical Flow Hardwall Modular (from cleanairproducts.com) |
Bio-Safe Cleanrooms Bio-Safe Cleanrooms eliminate cracks, have powder coated double walls, stainless steel panels, BioSafe Modular Cleanroom from Terra Universal (from terrauniversal.com) |
Softwall Cleanrooms Softwall Cleanrooms are a soft sided, tent like structure. Softwall Cleanroom (from cleanroomsbyunited.com) |
Powder Containment Cleanrooms Powder Containment Cleanrooms has a HEPA filtered clean zone with rear mounted air vents to draw air and powder away from the operator. Powder Containment Cleanroom (image from Production Automation Corporation) |
Explosion proof Cleanrooms Explosion proof Cleanrooms are expected to be explosion proof. For industries that work with volatile chemicals, Explosion Proof Bio-Safe Cleanroom (from terrauniversal.com) |
Fire resistant Cleanrooms Fire resistant Cleanrooms have walls made of chemical, thermal, and fire resistant materials such as fluoropolymers. Fire Resistant Hardwall Cleanroom (from terrauniversal.com) |
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