An ISO 5 Class clean room, also known as Class 100 cleanroom, is a soft- or hard-sided wall manufactured structure that utilizes HEPA filtration systems to maintain air cleanliness levels of a maximum of 100 particles (≥0.5 µm) per cubic meter of inside air. ISO Class 5 cleanroom purification systems must provide filter coverage of 60-70% and a minimum of 300 air changes per hour. The standard air flow rate for a Class 100 clean room is 36-65 CFM per square foot.

An ISO 6 clean room (Class 1000 cleanroom) is a soft- or hard-sided wall manufactured structure that utilizes HEPA filtration systems to maintain air cleanliness levels of a maximum of 1,000 particles (≥0.5 µm) per cubic meter of inside air. Class 1000 cleanroom filtration system must provide filter coverage of 20-30% and – a minimum of 180 air changes per hour. The standard air flow rate for an ISO 6 filtration system is 18-32 CFM per square foot.

An ISO 7 clean room (Class 10,000 cleanroom) is a hard-sided wall manufactured facility that utilizes HEPA filtration systems to maintain air cleanliness levels of a maximum of 10,000 particles (≥0.5µm) per cubic foot. Class 10,000 cleanroom filtration systems must provide filter coverage of 15-25% and – a minimum of 60 air changes per hour. The standard air flow rate for an ISO 7 filtration system is 9-16 CFM per square foot.

ISO 8 cleanrooms, also known as Class 100,000 cleanrooms, can be modular or soft-walled and have a maximum particle count of 100,000 particles (≥0.5 um) per cubic foot of interior air. They are required to have HEPA filtration coverage over 4-5% of the area and provide a minimum of 20 air exchanges per hour with air flow rates of 4-8 CFM per square foot.