Cleanroom Measurement Technology for Floors & Walls

The white paper begins with an overview of the importance of a hygienic manufacturing environment. “In order to minimize contamination risks during manufacturing processes, production environments need to be carefully planned to ensure that no sources of contamination will be present in the final product,” say the authors. “Due to the large exposed surface area in production settings, coating materials that are used to make walls and floors need especially to be taken into consideration.” This relates largely to the particles they emit, but also includes chemicals, outgassing and other factors as well.

One of these factors is air quality, as described in the EU-GMP Guideline Annex 1 for the manufacture of sterile pharmaceutical products. In a typical production environment, for instance, particles between 10 and 20 μm in size make up the majority of airborne microorganisms. Reducing them by 5 μm or more automatically reduces the count.

Wear and tear are other factors — stresses caused by transport trolleys, forklifts, and other equipment and the potential they have in releasing particles from floor abrasion into the air. Further, if a material corrodes or becomes brittle and cracks as the result of an aggressive cleaning agent, it not only loses its material properties, but may also become a dangerous source of particulate emissions. Fraunhofer IPA developed a prototype “Cleanroom-suitable tribiological test bench IPA” to measure particulate emissions from material surfaces.

In case of reactive systems (e.g., organic resin floors versus tiles or ceramics), care must be taken to ensure that the outgassing of organic contaminants (VOCs) is kept to a minimum in order to protect employees and if sensitive processes are concerned the products as well. The quantity of organic compounds released into the air depends on surface area, outgassing time, age and temperature of the materials in question.

The process Fraunhofer IPA used to determine outgassing of various floor and wall coatings in this research involved a number of sophisticated measuring instruments and a micro chamber heating device that hold the test material pieces at 22° +/- 1° C for one hour before gasses were siphoned off for analysis.

Different materials react differently to the same chemicals. There are several internationally-recognized methods for assessing their resistance to them. Flooring materials, particularly in food and beverage plants, should have the highest level of resistance.

As a rule of thumb, the under-surface of a flooring system should be permanently sealed and liquid-proof. If it isn’t, liquid residues from a previous cleaning or disinfection process can linger for long periods. If the flooring has poor chemical resistance, it will likely start corroding as a result.

The procedure for assessing chemical resistance is called the ‘Immersion Test’. The flooring samples to be measured are placed in a receptacle filled with the chemical in question. The receptacle is then hermetically sealed. After being exposed for periods of one, three, six and 24 hours, the materials are examined under a microscope for blistering, discoloring, swelling, softening, reduced scratch resistance, and other effects, with results recorded in comparison. The chemicals used in the test present a representative spectrum of chemicals used in cleaning and disinfection agents.