Clean Room Ventilation: Hoses Under Special Stresses

A cleanroom is defined as a space that has a low concentration of airborne particles. Airborne particles are small pieces of matter that are suspended in the air and, for the most part, cannot be seen with the naked eye. Such areas are needed whenever particles present in the ambient air would interfere with the work taking place. For cleanroom ventilation, special ventilation hoses are used to transport the air. These hoses have a number of specific requirements to ensure that they do not contaminate the air with dust, microorganisms, or fibers.

By Mark Bobonick, Director of Sales & Operations, NORRES

Clean Room Specifications

Clean and ultra-clean rooms are typically used for manufacturing pharmaceutical products, medical equipment, and electronics. Through conditioned and controlled air, these rooms ensure that a production environment is safe from particles entering the ambient air and becoming a hazard to a product. There are two dominate class systems used to rank the ‘cleanness’ of cleanroom: the International Organization for Standardization (ISO 14644-1) classes, and the Federal Standard 209 (FS 209E) classes.

In the ISO classifications, cleanrooms are rated according to how much particulate of specific sizes exist per cubic meter. The ‘cleanest’ cleanroom in the ISO class is ISO 1 and the ‘dirtiest’ is a ISO 9. Similarly, the ‘cleanest’ cleanroom in the FS 209E class is a class 1 and the ‘dirtiest’ is a class 100,000. The most common ISO clean room classes are ISO 7 and ISO 8.1.

Common Uses

Room specifications can change significantly, depending on the cleanroom class. The parameters of each cleanroom include: room design, air treatment, refrigeration and air conditioning technology, air routing and airlock technology, insulation, as well as measurement and monitoring technology. These specifications play a particularly important role in sensitive areas such as photonics, microsystems technology or medical or biotechnology. Having dirt or other particles in the room air can not only falsify measurements or permanently damage sensitive devices such as breadboards, but can affect the quality and service life of various pieces of equipment; this is a particular concern in the packaging and filling sectors.

For example, there are a number of medical products manufactured in cleanrooms. Production in the clean room absolutely ensures that these same medical devices are not contaminated by particles in the surrounding air. Thus, the production of pharmaceuticals and medical devices is a highly regulated and officially monitored practice; it has numerous requirements for production and for quality management.

Importance of Ventilation

Sensitive goods are in good hands in cleanroom cabins, do, in large, to the ventilation systems used. Sophisticated air-conditioning and ventilation technology ensures constant air quality in the cleanroom: the incoming air is processed by means of filters to protect particularly sensitive products from foreign influences. “Air cleanliness is achieved by passing the air through HEPA filters using flow principles such as laminar flow. The more often the air passes through the HEPA filters, the fewer particles are left in the room air. The volume of air filtered in one hour divided by the volume of the room gives the number of air changes per hour.”1 Harmful impurities are removed by filtration, stale air is replaced, and the necessary air volume is provided to dissipate process heat. Clean rooms are thus the top class of air conditioning and ventilation technology.

As cleanroom ventilation is a demanding and future-oriented segment, a smooth and risk-free process is a necessary factor. Technical hoses are used to supply air to the filter systems used in the cleanroom. The technical hose as a machine component is therefore one of the most important components of a cleanroom.

Hose Properties for Cleanroom Applications

Polyurethane hoses are often used for cleanroom applications. The reason for their use is simple and straightforward, the product properties are ideal for use in cleanroom environments. Polyurethane ventilation hoses are characterized in particular by their high abrasion resistance, purity, transparency, and flexibility. Some manufacturers use a very high-quality PUR material blend that has an optimized and reinforced hose designs. As these features ensure that the hose has optimal smoothness, they experience much less abrasion during the conveying process than is the case with many other hoses and typically have a longer service life; costly replacement in the event of hose failure will therefore be a rare occurrence. If, for example, there is a hose failure in a ventilation system of a clean room, a replacement – depending on the design – can be complicated.

High purity polyurethan hoses also have a very high tensile strength when in use. This means that there is only a slight axial change in the length of the hose during use and consequently less internal corrugation of the hose. Light to medium weight models with appropriate construction are lighter, which offers an important advantage in terms of the handling and installation of the hose. This effectively saves time during installation and removal, allowing the ventilation system to convey clean air again, and the cleanroom process to continue.

Another very important product feature of hoses used in cleanroom ventilation is that flexible hoses, whether pressurized or unpressurized, also ensure that the required substance, or clean air, reaches exactly where it is needed, without unnecessary loss. Polyurethane aeration hoses have very good mechanical strength and extremely good chemical and hydrolytic resistance. These hoses also exhibit slower hot-air aging and better low-temperature flexibility, which proves to be a great advantage in ventilation applications.

Final Thoughts

International approvals for general hose technology are subsequently a decisive component in the daily business of many industries. Research and development within the scope of hose technology is based on the requirements of the respective industry. Technical hoses used for cleanroom ventilation are subject to strict regulations and are closely monitored. Special certifications are essential in order for hoses to be used in this segment. These strict controls are unavoidable because the air for the clean room is transported through the ventilation hoses.


  1. “Clean Room Classifications (ISO 8, ISO 7, ISO 6, ISO 5): Mecart.” MECART Cleanrooms, 6 May 2021,


Mark Bobonick is the Director of Sales and Operations of NORRES North America. He joined the NORRES team in early 2017 to further grow and establish the NORRES Brand’s global footprint. Responsible for all Sales Facets across North America.

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