Grey room or rather cleanroom?

For some years, the term ‘grey room’ has been used in customer discussions and specialist articles. But how exactly is a ‘grey room’ defined? And how does it differ from a cleanroom? To which degree is an exact definition of the terms relevant in practice? In this blog post, we have dealt with these questions in detail and show what is important in the context of this topic.

What is a grey room?

The term ‘grey room’ is used for spatially separated areas that are better in terms of air purity than the surrounding areas, but do not necessarily have to be of cleanroom quality and are not categorised in the common particle purity classes of air according to ISO 14644-1 or VDI 2083-1. Due to the consistent implementation of the metric measurement system and the substitution of the US Federal Standard 209E by ISO 14644-1, it may be possible to describe the cleanroom with a particle cleanliness class of ISO 9 or ISO 8. Much more important than this classification of particle concentrations in the air, is to define the cleanroom for the respective application and to specify actions that maintain it as the originally intended cleanroom.

What has to be defined?

• Determination of the materials to be used, which are necessary for the production of the room
• Quality specifications for the installation of the room
• Fresh air supply, which is enabled by fan-filter-modules or clean air modules
• Entry regulations for the clean environment
• Behavioural rules within this environment
• The choice of appropriate clothing required within such a cleanroom
• Cleaning regulations to ensure a consistently high quality of the supplied air
• Type of qualification and requalification
• Appointment of a person responsible for the cleanroom and equipping them with the necessary competences. This can be facilitated as part of training or counselling.
• Specification in the quality manual to ensure consistent quality
  
  

How is clean air produced?

Special clean air modules have been developed to achieve a specified low particle concentration in a room, which does not have to correspond to a defined cleanroom class. They can be used to achieve the above-mentioned air cleanliness classes ISO 8 and 9. Thanks to a fine dust filter, large particles are filtered out of the ambient air. The clean air is released into the clean environment. A high air flow rate (up to 2,750 m³/h) is achieved, enabling sufficient air filtration for many processes.

Classification of the term ‘grey room’

If a cleanroom is defined as a room regulated solely by air conditioning technology, this results in a classification of the term that was first defined in VDA 19/2. 

Classification in accordance with VDA 19/2 raises the question of how a cleanroom can be defined if no cleanliness-technical components are required. If clean air technology is used, it is considered a cleanroom by definition. Although a differentiating definition of the two terms should be given, it should not be the focus of the questions. The distinction as to whether a grey room, cleanroom or merely a clean zone is required can be easily answered after a basic analysis of the processes. It should not be forgotten that the cleanliness technologies mentioned are only a means to an end and should therefore only be designed to be as good as necessary and not as good as possible.

It is much more important to focus on products and production that are kept clean by corresponding cleanliness technology. As grey rooms and cleanrooms differ only minimally in terms of design, an exact definition of the two terms is rather unimportant for installation in practice. Much more interesting is the question of possible savings potential in the technical realisation of the cleanroom.

The following technical solutions, among others, are available to realise potential savings.

Definition according to VDA 19-2

Cleanliness level 2 (SaS2): Grey room

• Permanently installed structural separation from other areas 11
• Cleanliness-orientated regulation within the area
• Cleanliness-orientated regulation with regard to transfer of materials and personnel to neighbouring or other areas
• No clean air technology beyond room air conditioning clean air technology
  
  

1. Clean air modules

Clean air modules are very similar to the design of generally known fan-filter-modules (FFM/FFU). However, clean air modules are equipped with different filters. Fan-filter-modules are usually fitted with either HEPA or ULPA filters, whereas clean air modules are fitted with a class F9 fine filter element. Equipping with fine filter elements has less impact on the direct investment costs, but in the long term, running costs due to filter changes are minimised.

What is a clean air modul - SRM?

The requirement for higher air purity does not always entail the creation of a cost-intensive clean environment with high air purity. The clean air module was developed for areas where a higher level of air purity is required, but not necessarily with increased cleanroom quality. This module can be used universally. It can be integrated not only in room ceilings, but also in localised clean areas. The installation position is not important. The modules can be installed horizontally or vertically.

How does a clean air module work?

The clean air modules are equipped with appropriate filters and can ensure an achievable air quality of air cleanliness class ISO 8, which of course depends on the respective ambient conditions, the size of the rooms and the number of modules. This filter class also corresponds as far as possible to the final filter stage in air conditioning systems, as long as they have been designed with the appropriate qualifications. By using such modules and filters, defined areas or even local solutions can be supplied with sufficient air quality very easily and efficiently.

The clean air module works in a similar way to a fan-filter-module. With the help of the fan technology and the filter medium, the particles in the air are sucked, filtered and released into the environment. The difference here is the filter medium, which filters larger particles than a fan-filter-module. The module generates a low-particle and low-turbulence displacement flow. The degree of purity of this flow depends on the environment and the degree of separation of the filter material used.

An optional pre-filter can be used to increase the service life of the main filter in the event of heavy dust loads. The filter element can also be changed easily on the clean air side without tools.

Where can clean air modules be used?

These modules are usually used in environments where a higher level of air purity is required, but where a cleanroom environment is not necessary yet. Further information on such a module and more detailed technical information can also be found under the following link at our homepage.

2. Foil walls and ceilings for grey rooms

Foil walls and ceilings do not refer to the commonly known cleanroom foils. Although cleanroom foils are the material of choice in many areas, they also have some disadvantages. For example, they are rather difficult to clean, are very intense in odour for a long time and, in the case of PVC foils, can cause fire safety concerns.

Fire protection concerns, in particular, can negate corresponding foil wall and foil ceiling systems. These frame systems covered with fire protection foil can be integrated as ceiling and wall elements in lightweight construction and combined with clean air modules.

The decisive advantage of these systems over regular cleanroom foils is obvious: an existing fire protection concept with associated sprinkler system does not have to be relocated to the cleanroom, but can continue to be used as before. If a fire breaks out in an emergency, the fire protection film of the frame system tears open and the existing sprinkler system above the grey room can be activated as intended.

Conclusion

Whether grey room or cleanroom. The most important thing is to integrate the technical solutions in a practical and cost-effective way in order to optimally protect your sensitive products and processes from harmful particles and ensure a smooth production process. Simply contact us without obligation.