Big Blue Blog - Cleanroom Decontamination Plant, Cleaning Process

Garments used in high grade cleanroom manufacturing are not usually subjected to significant soiling or wear but for some operations such as medical device manufacture, tablet production and surface finishing, cleanroom garments may become soiled with a range of contaminants including ink, paint, powders and sealants.

If it is suspected that items for decontamination could be contaminated with harmful materials then the cleanroom decontamination plant must be informed prior to garment handling and processing.

Soiling may be removed using either a solvent (dry-clean) or wet-wash (water based) process.

Solvent processes may be used for the removal of paints, heavy oil and grease; however the solvent systems used pose a variety of particulate, chemical, microbiological, safety and environmental problems and so are rarely used for cleanroom product decontamination. Water based methods are therefore the usual choice for cleanroom product cleaning.

For a low grade cleanroom decontamination operation potable water is used, for high grade processing however, the water quality is usually improved e.g. by filtration or reverse osmosis (RO), to ensure a consistent and low bio-burden with low dissolved solids.

Water based processes may be used for the removal of all types of soiling and different cleaning requirements are addressed by selecting the appropriate chemicals, washing machine action, temperature and process time. By varying these parameters it is possible to remove soiling and reduce most staining to an acceptable level; however some materials, such as indelible printing ink, may be difficult to remove.

Following cleaning the items are dried using either  a tumble dryer or tunnel finisher.  Tumble dryers are used in high grade cleanroom decontamination with measured loads of damp items being mechanically tumbled in hot filtered air. 

The tumble drier is kept under positive pressure and fed with heated, filtered air which is exhausted to atmosphere after passing through the machine.

A tunnel dryer operates by passing hanging garments continuously through a hot air chamber fed with heated, filtered air, exhausted to atmosphere and this type of drying may be used for processing low grade cleanroom garments.