CLEANROOM ENCYCLOPEDIA
ISO 14644-1 cleanliness classes, explained simply
What do Class 5 to Class 8 mean? How is each class's particle limit calculated, and which class is enough for your application?
What is a cleanliness class?
ISO 14644-1 grades cleanroom air quality into Classes 1 to 9 according to the maximum number of particles allowed per cubic metre of air at specified sizes (0.1 to 5 µm). The lower the class number, the cleaner the air: Class 5 corresponds to about 3,520 particles of 0.5 µm per cubic metre, and Class 8 to 3,520,000.
In the pharmaceutical industry, Grades A/B/C/D of EU GMP Annex 1 correspond roughly to ISO 5 (in operation and at rest), ISO 5/7, ISO 7/8 and ISO 8, and microbial contamination limits are defined for them in addition to particle limits.
How do you choose the right class?
The choice of class depends on process sensitivity, the product's regulatory requirements and operating cost. Raising the class without reason sharply increases air change rates, energy consumption and filtration costs. Our advice is to map the process and its critical points first, then define a suitable class and pressure differential for each room.
- Identify the critical points of the process and the flow of materials and people
- Select a class for each room and define the pressure cascade
- Calculate the air change rate and HEPA filter coverage
- Draw up a monitoring plan and a schedule of periodic tests
Talk to the KGS technical team about your project
Tell us your requirements, the standard you work to and the capacity you need; the KGS engineering team will walk through the proposed approach with you.