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At Skov Industri, we develop and deliver cleanrooms and advanced cleanroom solutions for companies where controlled environments are a critical prerequisite for quality, safety, and documentation.
A cleanroom is a controlled production or research environment where work is carried out according to fixed requirements for cleanliness, particle control, and documentation. The purpose of a cleanroom is to keep conditions stable and minimize the risk of contamination, so quality and safety can be maintained in sensitive processes.
A modern cleanroom must not only meet technical requirements, but also function optimally in day-to-day operations. MATADOR Cleanrooms combine a high hygiene standard with effective noise reduction, which is a significant advantage in industrial production environments. Our cleanrooms contribute to a better working environment where noise levels are reduced, without compromising cleanliness and documentation.
Skov Industri delivers both positive- and negative-pressure cleanrooms in accordance with ISO 14644-1 as well as GMP, cGMP, and USP requirements. A positive-pressure cleanroom is typically used in production where preventing external contamination is essential. Here, the positive pressure ensures that air and particles are pushed out of the cleanroom.
To understand ISO positive-pressure cleanroom classifications, you first need to understand how these cleanrooms operate.
The clean air in a positive-pressure cleanroom is created by drawing air into the cleanroom through a series of HEPA (High-Efficiency Particle Air) filters and/or ULPA (Ultra Low Particulate Air) filters. This creates an environment with clean air and builds pressure in the cleanroom.
With air pressure in the room higher than the pressure in the surrounding environment, the air inside the positive-pressure cleanroom is subsequently pushed out of the room through ventilation ducts. In this way, contaminants generated by the processes performed inside the room are carried out. At the same time, the higher pressure inside the room prevents contaminants from entering the room via exhaust ventilation ducts.
With purified air being drawn in and contaminants being pushed out, positive-pressure cleanrooms are classified according to the concentration of airborne particles inside them and the size of those particles. The goal is to minimize both the number and size of particles in a cleanroom through continuous pressure control and frequent air changes.
The ISO standard for cleanroom classifications, 14644-1, introduced by the International Organization for Standardization, has been in effect since 2001. The latest version is from 2015. It classifies cleanrooms by cross-referencing the size of measured particles (for example, 0.5 μm) with the maximum number of particles of that size per m3 that can be accepted in a cleanroom of the relevant type.
ISO 14644-1 cleanroom classifications
ISO cleanroom classifications largely align with the older US Federal Standard 209, which was in effect from 1998 to 2001. Although it has officially been out of use for years, it is still widely cited and can be easily cross-referenced with ISO classifications.
Note that ISO 14664-1 is stated in m3.
Approximate comparison of ISO 14644-1, FS 209, and EU GMP
To understand ISO classifications for positive-pressure cleanrooms, it is important to first understand how a positive-pressure cleanroom functions in practice.
In a positive-pressure cleanroom, clean air is created by supplying air to the room through HEPA (High-Efficiency Particulate Air) filters and in some cases ULPA (Ultra Low Particulate Air) filters. The filtration removes particles from the air, allowing the cleanroom to maintain the required cleanliness according to ISO 14644-1. At the same time, a stable air pressure is built up because more filtered air is supplied than is exhausted.
When the pressure inside the cleanroom is higher than in the surrounding areas, the air will naturally move out of the cleanroom through controlled exhausts and ventilation routes. The outgoing air carries particles and contamination away that may arise from processes and activity inside the cleanroom. In this way, positive pressure helps keep the environment stable and controlled.
An important effect of positive pressure is that it also acts as a “barrier” against external contamination. Because the air moves outward, it becomes much more difficult for particles to enter the cleanroom through openings, joints, or ventilation ducts. The result is a safer and more consistent environment where cleanliness and documentation can be maintained over time.
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In addition to keeping the level of airborne particles within the limits of ISO 14644-1, several industries also have requirements for ventilation and air exchange in cleanrooms. Especially in microelectronics facilities, requirements for air change rate (ACR) are common, and the same focus is increasingly seen in medical and pharmaceutical production where stable operation and documentation are essential.
For almost all ISO classes, there are recommended ACH ranges, but the correct ventilation always depends on how the cleanroom is used in practice. It is influenced by factors such as the number of people in the cleanroom, process equipment, heat load, particle sources, and how often there is access in and out through doors, airlocks, and gates. This means that two cleanrooms with the same ISO classification can have different ACH requirements depending on operation and workflows.
As a supplier of cleanroom solutions, we work closely with ventilation suppliers during both design and installation to ensure that air exchange, filtration, and pressure conditions match the desired classification and your production needs.
Read more about cleanrooms in our learning center here, or contact us for sparring on ventilation, ACH, and cleanroom requirements.
Rule of thumb for number of air changes per hour according to ISO 14644-1 classes.
Skov Industri følger vores kunder hele vejen fra indledende behovsafdækning og teknisk rådgivning til projektering, produktion og montage af renrum. Resultatet er gennemprøvede renrumsløsninger, der understøtter stabile processer, høj produktkvalitet og dokumenteret compliance.
Kontakt Skov Industri for en professionel dialog om, hvordan et renrum kan integreres i jeres produktionsmiljø og skabe optimale rammer for jeres forretning.
MATADOR Cleanrooms are developed with a focus on sustainability and long service life. Each cleanroom is 100% recyclable and can be dismantled, moved, or rebuilt if needs change. This means a cleanroom is not a static solution, but a flexible part of a company’s production strategy. This approach reduces both resource consumption and the costs of future rebuilds.
Floor solutions can be adapted with floor coverings, floating floors, or floors prepared for ventilation according to the relevant ISO requirements. We can also deliver windows, doors, airlocks, and gates for cleanrooms, including solutions with automation and interlock, and we can dimension roof structures to handle loads from ventilation units and technical installations.
