Clean rooms were initially developed in the United States, where they were designed and classified, including at a regulatory level, for the emerging semiconductor industry: even the smallest particle suspended in dust can cause damage to components during processing and assembly. As the industrial world evolved, clean rooms also found wide use in the food, pharmaceutical, chemical, biotechnological and aerospace fields, whose processes require an environment as sterile as possible and free of polluting and harmful elements.
The clean room is characterised by:
a high degree of air purity;
a reduced content of dust and microparticles;
presence of filtering systems;
presence of filtered forced air recirculation systems, which feed air in from the ceiling and take it out from grilles located near the floor;
constant control of pressure and humidity parameters.
The enclosure of such rooms, in addition to guaranteeing high performance with respect to the internal microclimate, must necessarily meet all the requirements of a building component in terms of thermal insulation, load-bearing capacity, durability, physical and chemical resistance, ease of cleaning and, above all, reaction to fire, the latter being an increasingly prominent issue in today's world of construction.
Use of sandwich panels for clean room construction
ISO 14644 defines some guidelines regarding the construction of a clean room and the required technical-functional characteristics:
windows and doors must be made of double safety glass;
the perimeter walls and roofing must be made of sandwich panels, assembled in such a way as to prevent the entry of dust and pollutants and to facilitate the cleaning of surfaces;
provide finishes appropriate to the activity performed, with preference given to smooth surfaces as they are easy to clean and less prone to dirt accumulation;
provide neutral white lighting.
The use of Isopan sandwich panels is therefore particularly suitable, which manage to combine technical performance and ease and speed of installation, with the guarantee of a result that achieves high standards of efficiency.
The possibility of having different types of joints between the individual panels makes it possible to guarantee a perfect seal depending on the requirements and the product used.
Since clean rooms are working environments, in which there is a constant and continuous presence of operators, the safety and resistance of the enclosure is of primary importance, especially with regard to the resistance and behaviour of the materials in case of fire.
The components that make up the clean room must necessarily guarantee a certain durability should they come into contact with flames, either from the inside to protect the outside environment, or vice versa.
There are two features the panels must have:
reaction to fire.
Fire resistance refers to the maximum time for which the component guarantees resistance in terms of stability, tightness and insulation, while reaction to fire refers to the behaviour of the component when it comes into direct contact with flame or other form of heat.
Sandwich panels, thanks to their layered composition, generally consisting of two metal surfaces and an interposed insulating material, are able to achieve high levels of fire resistance and reaction ratings, making them ideal candidates for the construction of the environments in question.
Fire resistance and reaction characteristics of sandwich panels
Legislation prescribes and defines classes of resistance and reaction to fire for building materials. Depending on the field of application and the activity carried out on the premises, the specific fire prevention file, drawn up by a qualified professional, determines the degree of fire resistance and reaction to fire that the materials must have.
Fire resistance, meaning the maximum time for which the material or product provides resistance in terms of stability, tightness and insulation, is identified by the abbreviation REI:
the letter R refers to the mechanical and structural strength of the component;
the letter E refers to the component's ability to prevent the passage of fumes and vapours;
letter I refers to the ability of the component to provide thermal insulation with respect to the part not in contact with the heat source.
The degree of fire resistance is indicated in minutes (from a minimum of 15 to a maximum of 360), which defines how long the material ensures the resistance indicated in the abbreviation.
Reaction to fire is instead indicated by an abbreviation consisting of 3 components:
the degree of reaction to fire according to flame propagation speed, extinguishing time, damaged area and presence of dripping, identified in the certification by a letter ranging from F (for products most easily combustible) to A2 and A1 (for non-combustible products);
smoke production, identified by the letter s together with a number, from 1 to 3 (the lower the number, the less smoke is produced);
presence of dripping phenomena, identified by the letter d together with a number, from 0 to 2 (the lower the number, the lower the dripping phenomenon).
Isopan panels ensure high performance in terms of both resistance and reaction to fire.
Isopan panels in clean room construction
The Isopan catalogue includes various products suitable for clean room construction, such as Isofrozen panels.
These products are in fact designed for the construction of environments in which it is of primary importance to ensure compartmentalisation and sealing to guarantee the control of the internal atmosphere, thanks also to different types of joints depending on the requirements of the project.
Specifically, the Isofrozen panel has one of the highest fire reaction classes, “B-s1,d0”, and can achieve, for the 200 mm thick panel, a fire resistance performance of EI60.
Isopan's ongoing commitment to innovation and environmental sustainability is embodied in its LEAF technology, which aims to minimise environmental impacts while ensuring excellent performance.
With regard to fire reaction certification, Isopan's LEAF solutions achieved the “B-s1,d0” certification class, the highest in Europe for products with polyurethane.
This technology also makes it possible to improve the thermal performance of the insulation panel, thus enabling a higher thermal insulation performance for the same thickness.
Marta Lupi, materials engineer and R&D Project Manager at Isopan, is involved in research projects aimed at identifying new product and process solutions. She works closely with universities, research centres and strategic partners for innovation.