Definition: What is a cleanroom?
01 April 2022

Definition: What is a cleanroom?

State-of-the-art research, development and manufacturing processes increasingly require environmental conditions in which the airborne particle concentration should not exceed specific limits.

Definition: What is a cleanroom?

Room with a defined concentration of airborne particles, designed and used in a way that the number of particles introduced into the room or originating and being deposited in the room is as small as possible, and in which other cleanliness-relevant parameters such as temperature, humidity and pressure can be controlled as required.” (VDI 2083-1)

The incoming air is processed by means of HEPA and ULPA filters to protect particularly sensitive products in research, technology, industry, and pharmaceutical applications against harmful environmental influences. To this end, also the staff in the clean room must comply with rules of conduct that dictate defined protective clothing.

Cleanrooms can cover areas of various sizes. From individual equipment to complete production facilities. The appropriate solution always depends on the requirements of contamination control.

The probably most important requirement is the airborne particulate cleanliness class. This is classified by specifying the maximum permitted number of airborne particles and divided into 9 ISO classes:




After the ISO class of the clean room has been specified, the type of air flow around the product must be considered.
Relevant flow principles in the cleanroom

1. Turbulent dilution flow: “non-unidirectional airflow. Air distribution during which primary air entering the cleanroom or clean area is mixed with the room air by means of induction.” (ISO 14644-1 - 2016-06) The filtered clean air is introduced into the clean room with a swirling effect and generates an increasing dilution of the particle concentration. With this flow principle, the staff’s behaviour according to clean room conditions is particularly important in order to ensure the required airborne particulate cleanliness class.

2. Low-turbulence displacement flow: “unidirectional airflow, regulated airflow with uniform speed across the entire cross-section of a cleanroom or clean area, which is regarded as parallel airflow.” (DIN EN ISO 14644-1 - 2016-06) This is also called “laminar flow” and requires a low-turbulence inflow. In this procedure, the air escapes on the opposite side, normally consisting of a perforated double floor. From there, it returns into the recirculation device where it is filtered again. The low-turbulence displacement flow is particularly suitable for sensitive work areas.

Fan-filter modules (FFM) in cleanrooms

Fan-filter modules and clean air modules are used for clean air supply in controlled environments. They filter the air and form the active elements in clean rooms, clean air workstations, mini environments or clean room transport systems.

Fan-filter modules (FFM) consist of three main components:

  • housing
  • fans
  • main filter (HEPA filter, ULPA filter); optionally pre-filter

Basic structure of cleanrooms

Each cleanroom environment has different installation conditions and requirements. Depending on those, the solution can feature solid wall elements (hardwall) or foil curtains (softwall) and equipment as well as come in different sizes.

Structure of softwall cabins: PVC curtains shield the local clean air area against environmental influences. Several fan-filter modules ensure the supply with “pure” air. The exhaust air can easily escape the clean room under the curtains.

Advantages of softwall cabins:

  • individual planning and installation
  • easy integration of work surfaces, shelves, wet work stations, separately enclosed inspection workstations as well as airlocks for people and material
  • adaptation possibility for expansion of the production area
  • additional fan-filter modules can be installed easily

Structure of hardwall cabins: Using a hardwall cabin, you can quickly create a clean environment for a specific process. Standardized segments allow simple setup of different cabin sizes.

Advantages of hardwall cabins:

  • available in all purity classes
  • suitable for use in production areas with very narrow climate tolerances
  • precise examination of products or production processes possible

Advantages of modular cleanroom systems:

  • individual planning and installation
  • easy integration of work surfaces, shelves, wet work stations, separately enclosed inspection workstations as well as airlocks for people and material
  • adaptation possibility for expansion of the production area
  • additional fan-filter modules can be installed easily

Advantages of clean working zones:

  • the principle of the modular cleanroom can be transferred to work benches, individual cabins and mini environments
  • individual modules are easy to connect and tailor to customer requirements
  • systematic use of the available space
  • provides an improvement in the purity class also outside the work surfaces

Cleanroom technology in its entirety has developed enormously in the economic field. There must be an appropriate ratio of quality and costs. The comparison shows that a standard cleanroom is not always necessary.

The modular cleanroom systems prove to be an appropriate solution especially for small and medium-sized enterprises as they ensure a high degree of flexibility and the ability to modify production areas. The transition between modular cleanroom systems and clean work zones is fluent.

Flexible cleanroom solutions

A cleanroom solution is vital for applications in research, development and production which must take place in ultra-low particle environments. However, the best option is not always a standard cleanroom. Cost-efficiency, above all, is an important factor in this context. A rental cleanroom, for instance, could be a valid solution for small and medium-sized enterprises to avoid the high investment in a standard cleanroom. Moreover, rental cleanrooms offer a high degree of flexibility to provide short-term solutions for order peaks, measuring and testing tasks.

Requirements on mobile rental cleanrooms:

  • easy assembly and disassembly
  • can be adapted flexibly
  • meets highest expectations

Grey room

The term grey room is used for spatially separate areas whose air purity is better than that of the surrounding spaces, but which do not necessarily offer clean room quality. In order to achieve the required cleanliness, special clean air modules have been developed. Thanks to a fine dust filter, coarse particles are filtered from the ambient air. These modules achieve a higher airflow rate and adequate air filtration.