ISO 5 cleanrooms, also known as Class 100 cleanrooms, are controlled environments with strict specifications for air quality and particulate contamination control. The ISO 5 designation comes from the ISO 14644 cleanroom classification standard, which rates cleanrooms from ISO 1 (the best air quality) to ISO 9 (the lowest air quality).
ISO 5 indicates that the concentration of airborne particles 0.5 μm or larger must not exceed a total of 3,520 particles per cubic meter of air. This is an extremely stringent level that requires high-efficiency filtration and air change rates to achieve. The purpose of maintaining ISO 5 air quality is to minimize contamination risks for sensitive processes and products in industries like pharmaceuticals, medical devices, electronics, and aerospace.
Complying with ISO 5 specifications requires careful control over air filtration, room pressurization, temperature/humidity, personnel gowning procedures, equipment design, and cleaning/disinfection protocols. Facilities must demonstrate consistent adherence to ISO 5 criteria through rigorous particle counting and environmental monitoring.
ISO Cleanroom Standards
The ISO 14644 series sets standards for cleanrooms and associated controlled environments. The main standard for classifying air cleanliness is ISO 14644-1.
ISO 14644-1 classifies air cleanliness into concentration levels of airborne particles in cleanrooms and associated environments. It specifies classifications and testing methods to demonstrate continuing compliance with the specified classification.
ISO 14644-1 defines particle concentration limits for cleanrooms in terms of the number of particles of specific sizes per volume of air. The classification scheme consists of 9 classes: ISO 1, ISO 2, ISO 3, ISO 4, ISO 5, ISO 6, ISO 7, ISO 8 and ISO 9. With each increasing ISO number, the allowable number of particles of a given size per volume of air increases as well. So ISO 1 represents the cleanest class, while ISO 9 represents the highest particle concentration.
The main particle sizes considered are ≥0.1 μm, ≥0.2 μm, ≥0.3 μm, ≥0.5 μm, and ≥5.0 μm. The ISO 5 classification specifically sets limits for concentrations of ≥0.5 μm and ≥5.0 μm particles.
ISO 5 Specifications
The ISO 5 cleanroom specification sets strict limits on the maximum number of particles of certain sizes permitted per volume of air. Specifically, for particles equal to and greater than 0.1 μm, the ISO 5 particle concentration limit is 3,520 particles per cubic meter of air or 100 particles per cubic foot (as specified in ISO 14644-1). For particles equal to and greater than 0.2 μm, the limit is 237 particles per cubic meter of air or 7 particles per cubic foot. And for particles equal to and greater than 0.3 μm, the limit is 102 particles per cubic meter of air or 3 particles per cubic foot.
To achieve these low particle counts, ISO 5 cleanrooms require a high air change rate. The ISO standard specifies an air change rate of at least 20 air changes per hour is needed. This high air filtration and ventilation flushes out contaminants and brings in clean filtered air to dilute particle concentration.
Personnel entering an ISO 5 cleanroom are required to wear full protective garments, including head and face covers, sterile gloves, sterilized gowns, and boots. All exposed skin must be covered to minimize contamination from people. There are strict procedures for gowning that must be followed before entering the cleanroom.
Air Filtration
ISO 5 cleanrooms require extremely high levels of air filtration to maintain the stringent particle counts. This is achieved through the use of high-efficiency particulate air (HEPA) filters or ultra-low particulate air (ULPA) filters. As per ISO standards, HEPA filters must remove 99.97% of particles 0.3 microns in size, while ULPA filters remove 99.999% of particles 0.12 microns in size (CleanAir Products).
The filtered air is supplied into the cleanroom through fan filter units (FFUs) mounted on the ceiling. FFUs contain the HEPA/ULPA filters as well as fans to drive and distribute the air. The FFUs continually filter and recirculate air within the cleanroom at a high air change rate, removing particles and refreshing the air to maintain ISO 5 specifications. According to ISO 14644-1, an ISO 5 cleanroom requires at least 240-600 air changes per hour with 35-70% ceiling coverage by FFUs (American Cleanrooms).
Room Pressurization
ISO 5 cleanrooms utilize positive pressure to maintain strict air quality standards. This involves creating higher air pressure inside the cleanroom relative to adjacent spaces. Positive differential pressure prevents contaminated air from flowing into the cleanroom environment.
ISO 14644-4 recommends a pressure differential from room to room of 5 to 20 Pascals (0.02″ to 0.08″ w.g.). Maintaining an optimal pressure differential between an ISO 5 space and less clean areas ensures airflow goes from clean to dirty areas only (Cleanroom Pressure Differential Testing). Larger pressure differentials may be required depending on the cleanroom application.
Monitoring differential pressure with gauges and alarms helps quickly identify breaches. Rapid response to pressure fluctuations enables corrective action before contamination occurs (Ensuring minimal pressure difference in cleanrooms).
Temperature and Humidity
ISO 5 cleanrooms have strict temperature and humidity requirements to maintain proper conditions for processes. The temperature is generally controlled between 15-25°C (59-77°F), with a typical range of 20-23°C (68-73°F) (Pharmaceutical Engineering). Humidity is also regulated, usually between 30-40% relative humidity year-round (Blue Thunder Technologies). This controlled environment prevents excess moisture and minimizes particles that can interfere with processes. Specific temperature and humidity setpoints may vary based on industry regulations and process requirements.
Cleaning and Disinfection
Proper cleaning and disinfection procedures are critical for maintaining ISO 5 air cleanliness standards. Cleanrooms should have written cleaning procedures that specify disinfectants, cleaning techniques, frequencies, and documentation requirements.
Typical daily cleanroom cleaning procedures involve wiping down all work surfaces and floors with 70% isopropyl alcohol or other approved disinfectants. Weekly and monthly deep cleaning should also be scheduled to thoroughly disinfect all surfaces, equipment, and the HVAC system. Gowning areas and entryways may require more frequent cleaning.
Cleanroom cleaning documentation should record the date, time, cleaner’s name, areas cleaned, and any deviations from protocol. This provides quality control and can help identify trends or issues with the cleaning process [1].
Gowning and Personnel Requirements
Proper gowning procedures are essential for maintaining the cleanliness of an ISO 5 environment. The gowning sequence should proceed from the dirtiest items to the cleanest. A typical gowning procedure would be:
- Step into sticky mats to remove gross contamination from shoes.
- Put on shoe covers.
- Put on coverall or lab coat.
- Put on hood.
- Put on face mask.
- Put on gloves.
When exiting the ISO 5 space, the process is reversed, removing the cleanest items first. All garments are disposed of or laundered after use.
The gowning requirements become more stringent for cleaner ISO ratings. For ISO 5, full coveralls, hoods, gloves, masks and shoe covers are required (Sunline Supply). Any exposed skin or hair is a contamination risk.
Personnel working in ISO 5 spaces require extensive training on proper gowning, entry/exit protocols, maintaining unidirectional airflow, and avoiding behaviors that generate particles like loud talking. Maintaining cleanroom discipline and following all procedures is critical.
Process Equipment
ISO 5 cleanrooms require specialized process equipment and material handling protocols to maintain the extremely stringent particulate levels. Some common types of equipment used in ISO 5 cleanrooms include:
- Laminar flow hoods – Provide ultra clean air over critical work areas. The hood blows HEPA-filtered air in a uni-directional stream over the work surface, sweeping away particles.
- Isolation systems – Used to transfer materials in and out of the cleanroom while maintaining isolation from the external environment. Examples include pass-through chambers, rapid transfer ports, and airlocks.
- Robotic arms – Manipulate materials within the cleanroom without introducing contamination from personnel. Robot arms may be fixed or mobile.
- Cleanroom tools – Hand tools such as tweezers, screwdrivers, and wrenches, designed not to shed particles during use.
- Cleanroom monitors – Particulate counters continuously monitor the cleanroom environment.
All equipment and tool surfaces are specially treated to minimize particle generation. Strict protocols govern material transfer into and within the cleanroom. Parts are double-bagged in protective cleanroom packaging, hand carried through airlocks, and opened only within the cleanroom.
Applications
ISO 5 cleanrooms are commonly used in pharmaceutical manufacturing and medical device assembly where high levels of cleanliness and control of particulates are critical. Some examples of pharmaceutical applications include:
- Aseptic processing and filling of injectable drugs, vaccines, and IV solutions
- Manufacturing of oral solid dosage forms like tablets and capsules
- Packaging of pharmaceuticals and medical devices
For medical devices, ISO 5 cleanrooms may be used for manufacturing and assembly of sensitive implants, prosthetics, catheters, surgical tools, and other devices that must avoid contamination. Maintaining ISO 5 conditions protects the sterility and biocompatibility of these medical products.
Other industries that utilize ISO 5 cleanrooms include semiconductor and electronics manufacturing, LED and solar panel production, nanotechnology research, and certain food processing applications where low particulate levels are required.