When a cleanroom is completed, it must also be measured for the corresponding cleanroom parameters in accordance with the standard. Whether this is called start-up, cleanroom acceptance measurement or qualification is not decisive at first. The decisive factor is that the general conditions for the measurements are defined.
This includes the occupancy status of the cleanroom.
The occupancy states are defindes as follows:
As built:
Occupancy state where the installation is complete with all services connected and functioning but with no production equipment, materials, or personnel present.
At rest:
Occupancy state where the installation is complete with equipment installed and operating in a manner agreed upon by customer and supplier, but with no personnel present.
In operation:
Occupany state where the installation is functioning in the specified manner, with the specified number of personnel present and working in the manner agreed upon.
VDI 2083-3-2022 recommends the operating states ‘as built’, ‘at rest’ and ‘in operation’.
As built:
Condition where the installation is complete with all services connected and functioning but with no production equipment, materials, or personnel present
At rest:
Condition where the installation is complete with equipment installed and operating in a manner agreed upon by the customer and supplier, but with no personnel present
In operation:
agreed condition of the cleanroom or clean area operated in the specified operating mode with the equipment in operation and with the specified number of persons present.
ISO 14644-2 specifies that the acceptance measurement must be carried out in the ‘as built’ and ‘in operation’ states.
Volume 4 Annex 1 (2008) (translation from German Federal Gazette)
In order to meet the conditions in the operating state, these areas must be designed in such a way that certain air purity levels are achieved in the non-operating state. The ‘’resting state‘’ is the state in which the production equipment is installed and in operation without the presence of operating personnel. The ‘operating state’ is the state in which the system is operated in the intended manner with the specified number of persons.
The ‘operating’ and ‘ resting’ states should be defined for each cleanroom or cleanroom area.
In any case, the time and operating status of the acceptance test must be agreed between the operator and the cleanroom manufacturer and/or qualifier.
The quality of the cleanroom environment is not only influenced by the cleanroom construction or the clean environment, but also to a large part by the process and any personnel present. Therefore, the constructor of a clean environment or a cleanroom will normally only guarantee compliance with the environmental conditions as built or at rest (without production equipment), as he cannot influence contamination by equipment or personnel, or only to a limited extent. On the other hand, ‘only’ the ‘in operation’ measurement is actually decisive for the operator, as the product is manufactured under these conditions.
In order to find possible sources of contamination in the cleanroom in a targeted manner, it can be useful to carry out the measurements in different occupancy states, in particular ‘at rest’ with and without equipment and ‘in operation’.
The production equipment in change can have both a negative (e.g. particle generation through abrasion, heat sources) and a positive (e.g. additional particle purification through recirculating air filter units / workbenches) influence on the clean environment.
For measurements ‘in operation’ , appropriate procedures must be considered if the test run cannot be carried out with the original product, as additional measurement technicians may be present in the room during these measurements, which can of course pose an additional risk to the product. This can lead to the product quality being affected by the measurements.
In addition, the EU GMP guidelines require the testing of worst-case scenarios. Here, for example, you can test the maximum number of people that can be permitted in the room. There are always situations in which there are more people in the cleanroom than are necessary for normal operation (e.g. technicians, auditors, quality staff).
All of these points should be taken into account when selecting the operating status. Especially as not all cleanroom measurements are recommended in all occupancy states. Here too, the type and scope of the measurements must be precisely agreed in advance.
We are happy to advise and help you on this topic.