An example of cost-effective creation of partially sterile clean air zones

© Spetec

For approximately 25 years, the company SPETEC Gesellschaft für Labor- und Reinraumtechnik mbH in Erding has been involved in the design and construction of cleanrooms of various sizes, which can be variably designed, built, and installed according to requirements or customer wishes. These products have been used in a wide range of fields so far. They are installed in various industrial buildings where particularly clean conditions must be maintained – where a pure atmosphere is necessary or recommended.

The typical construction feature is a so-called laminar flow module, equipped with a high-quality fan and a filtration system consisting of a pre-filter and a high-performance HEPA 14 filter. The designation HEPA 14 means that this filter is capable of retaining 99.995% of all particles with a diameter of 0.12 μm. The size of the module can be variable; it depends on the application purpose. To create high-quality clean air workstations, which are located either in a sealed cleanroom or in air-conditioned rooms, it has proven effective to hang a module above this space.

In a laminar clean air flow, a particle- and germ-free space is created, which is enclosed. For larger cleanrooms, called cleanroom cells, multiple modules can also be installed side by side and connected. If the cleanroom to be created is equipped with devices or furniture, SPETEC recommends using a clean air flow with low turbulence to ensure air exchange everywhere. The manufacturing of the modules and all accessories is carried out by SPETEC according to GMP (Good Manufacturing Practice) guidelines and is accordingly certified. In addition to the standard sizes available from the company's catalog, there are various options.

Customer requests for different sizes can be fulfilled through in-house manufacturing. The size of the cleanroom area can be freely chosen based on SPETEC's experience. The modern modules, which can be hung at any height or attached to the ceiling, are now characterized by quiet operation.

In the case of new constructions or renovations, such a module can also be installed in ceilings. This type of clean air generation offers a cost-effective alternative to elaborate complete cleanrooms. With good sealing of entrances and windows, a similar level of cleanroom quality can be achieved with continuous operation.

The properties and quality classes of cleanrooms are specified in the standards DIN EN ISO 14644, Part 1 (Classes 1 – 9) or in the EU-GMP guidelines (Classes A – D).

The ambient air and humans have the greatest influence on the cleanliness of objects. Additionally, contamination of cleanrooms occurs due to particle transport through the air, the introduction of particles on technical surfaces, and particle generation by equipment, personnel, and ongoing processes. Just through skin and clothing, more than 600 million particles (> 0.5 μm diameter) are released per person per layer in a Class 8 cleanroom. This, along with measurements of particle release of the same diameter during personnel movements in protective clothing (20,000 particles when sitting with slight forearm movement; 50,000 when standing up; and 80,000 when walking slowly), is based on data from the Fraunhofer Institute for Process Engineering and Automation (IPA) in Stuttgart. In ambient air, besides microdroplets, dust, and lint particles, bacteria (~ 0.5 – 50 μm diameter) and viruses (~ 0.005 – 0.1 μm diameter) are predominantly present. Resistant germs against antibiotics can be particularly dangerous to humans in medical areas. Most of these particles are relatively harmless to healthy people. However, the situation is different for sick individuals, especially those with acute immune deficiencies or open wounds, who need to be treated in ambient air or in air-conditioned rooms with recirculating air systems.

To achieve an even higher purity class, SPETEC recommends delimiting the room with a lamella curtain. This allows handling in a particle- and germ-free environment underneath. Sensitive devices or tools can be operated or stored beneath it. All of this can be implemented without major structural modifications.

In summary, it can be said that a costly complete cleanroom is not always necessary, especially if personnel need to move through the space. Depending on the requirement, the cost-effective, flexible modules from SPETEC can also be installed or hung.