ISO Class 7 cleanrooms, also known as ISO 7 or Class 10,000 cleanrooms, are controlled environments with strict particulate cleanliness specifications. As defined in the ISO 14644-1 standard, ISO Class 7 cleanrooms must maintain air particle counts of ≤10,000 particles/m3 for particles ≥0.5μm in diameter.
ISO 7 cleanrooms provide a clean manufacturing environment for industries like pharmaceuticals, medical devices, optics, microelectronics, and food processing where minimizing particulates is critical. Common applications in ISO Class 7 cleanrooms include laser research, lens coating, semiconductor production, sterile filling, and biomedical product assembly.
Compared to lower class ISO cleanrooms used for electronics or industrial manufacturing, the stringent particulate requirements for ISO 7 make them suitable when manufacturing sensitive medical and pharmaceutical products. However, ISO 7 cleanrooms are less particle-controlled than higher ISO classes used for the most critical aseptic manufacturing processes.
Particle Count Limits
ISO Class 7 cleanrooms have strict particle count limits to maintain air cleanliness. The maximum allowable particle concentration is:
- 352,000 particles/m3 for particles ≥0.5 μm in size
- 2,930 particles/m3 for particles ≥5.0 μm in size
To achieve these low particle counts, ISO Class 7 cleanrooms utilize HEPA filters that remove 99.97% of particles ≥0.3 μm in size. Regular air changes coupled with proper gowning procedures also help minimize particle contamination within the cleanroom.
According to the Clean Air Products article on ISO Class 7 cleanrooms, “An ISO 7 or Fed-Std 209E class 10,000 cleanroom must have 352,000 particles per cubic meter or less ≥0.5 μm sized particles, 83,200 particles per cubic meter or less for particles 1.0 μm and larger, and 2,930 particles per cubic meter or less for particles 5.0 μm and larger” (source).
Temperature & Humidity
ISO 14644-1 specifies that temperature and humidity in ISO Class 7 cleanrooms should generally be maintained within tightly controlled ranges. According to the Gelaire Bulletin, room temperature should be within 16°C to 19°C and relative humidity between 55% to 65%, unless otherwise specified. These ranges help minimize particle generation and growth.
As discussed on the Elsmar Quality Forum, humidity levels are critical for ISO Class 7 and 8 cleanrooms, with a typical recommendation between <65% RH and >30% RH. Air Innovations notes that 30-40% RH is ideal for most standard cleanrooms, but levels of 40-60% may be optimal for more sensitive applications like aerospace.
By keeping temperature and humidity within specified limits, ISO Class 7 cleanrooms provide optimized conditions to minimize risks of contamination.
Air Changes
ISO Class 7 cleanrooms require a minimum of 30 air changes per hour (MeCart). According to the ISO Class 7 specification, these cleanrooms need between 30-60 air changes per hour (American Cleanrooms). The air change rate helps regulate temperature, humidity, and contaminants within the cleanroom environment. By exchanging the air frequently, the cleanroom maintains the proper conditions and cleanliness for its operations.
Room Pressurization
ISO Class 7 cleanrooms are required to maintain a positive pressure differential relative to less clean adjoining spaces to prevent contamination ingress. The recommended pressure differential is 0.5 to 1.0 inch water gauge (w.g.) or 125 to 250 Pascals between ISO Class 7 and adjoining spaces like hallways or ante-rooms [1].
Maintaining this pressure differential helps ensure airflow is moving from cleaner to less clean areas. Airlocks and interlocking doors are commonly used between adjoining spaces to minimize disruption of the air balance when entering or exiting the cleanroom.
alarms are also suggested in ISO Class 7 cleanrooms to immediately indicate any pressure loss or reversal, as positive pressure must be constantly maintained for proper contamination control.
Gowning Requirements
The gowning requirements for ISO Class 7 cleanrooms help minimize contamination by personnel. Gowning procedures include wearing protective garments such as coveralls, frocks, hoods, overshoes, gloves, face masks, etc. The specific requirements may vary depending on the nature of operations, but some general guidelines are:
Full coveralls and hoods may be required in ISO 7 cleanrooms, along with safety glasses or goggles and gloves. Shoe covers or dedicated cleanroom shoes are recommended [1]. For less critical operations, frocks, bouffant caps, face masks, and gloves may suffice [2]. All garments are sterilized before use and worn in a specified sequence. Gloves are worn over the sleeves, and as the last item put on.
Care is taken to avoid shedding particles or bringing contaminants into the cleanroom. Personnel must avoid rapid movements that can shed particles. Meticulous gowning and degowning procedures are established and personnel are trained thoroughly.
Entry to ISO 7 cleanrooms is through airlocks or buffer zones. Required gowning procedures are posted and monitored for compliance. Only authorized and properly trained personnel are permitted entry.
Cleaning and Disinfection
Regular and thorough cleaning is critical in an ISO Class 7 cleanroom to remove contaminants and prevent particles from becoming airborne. Cleaning schedules and disinfection procedures should follow strict protocols.
Daily cleaning is recommended for ISO Class 7 cleanrooms, with weekly or monthly deep cleaning. All surfaces including floors, walls, ceilings, equipment, and tools should be cleaned. Cleaning should progress from higher to lower cleanliness areas [1].
Disinfectants are sterilized before entering the cleanroom [2]. Surfaces are first cleaned to remove contaminants, then disinfected using sterilized alcohol or hydrogen peroxide wipes. Cleanroom-safe disinfectants approved by the EPA are recommended. Floors may require mopping with disinfectant cleaners.
Cleaning tools like mops, buckets, and vacuums must also be disinfected regularly to prevent recontamination. All cleaning materials and waste are removed promptly from the cleanroom.
Material Requirements for ISO Class 7 Cleanrooms
ISO Class 7 cleanrooms have specific requirements for the types of materials used for construction. The goal is to minimize particles that could contaminate processes or products. According to the ISO 14644-1 standard, all materials should be selected based on chemical compatibility, cleanability, and durability.
Some common material requirements include:
- Flooring must be non-particle generating and non-porous, such as vinyl, epoxy resin, or welded stainless steel.
- Walls should be constructed from rigid non-particle shedding materials like aluminum, stainless steel, fiberglass reinforced plastic (FRP), or gypsum board with epoxy paint.
- Ceilings can be modular panels of vinyl, aluminum, or painted steel. They should be gasketed and flush mounted.
- Doors must have cleanable non-particle generating surfaces, with gasketing around frames.
- Windows and glazing should be made of laminated safety glass or acrylic materials.
- All fixtures, attachments, and trim should be permanently bonded to prevent particle accumulation.
Proper selection of construction materials is critical for controlling contamination and meeting ISO Class 7 requirements. All choices should minimize particles, outgassing, and shedding.
Certification
To achieve ISO Class 7 certification, a cleanroom must meet strict standards for air quality. Initial certification involves testing the cleanroom to confirm it meets the maximum allowable particle counts. An accredited testing organization samples air at multiple locations and counts particles in several size ranges, including ≥0.1 μm, ≥0.2 μm, ≥0.3 μm, ≥0.5 μm, and ≥5.0 μm. The testing process is described in ISO 14644-1.
For a cleanroom to be certified as ISO Class 7, it must not exceed 3,520,000 particles per cubic meter of ≥0.5 μm particles. In addition, the concentration limits must be met for all the specified particle sizes. Testing is conducted at the point of air supply and throughout the cleanroom space. All HEPA filters, air flow patterns, and pressure differentials are verified.
Once commissioned, cleanrooms require periodic re-certification every 6-12 months. Surveillance audits may be conducted in between the full certification audits. Recertification ensures the facilities continue meeting the original ISO class over time. Any changes to the cleanroom, such as filter replacements or layout changes, also require re-certification.
Facilities demonstrate their cleanroom meets ongoing ISO standards by displaying the testing and certification documents. Proper ISO certification proves the cleanroom provides the necessary level of air cleanliness for processes requiring controlled environments.
Sources:
https://www.strouse.com/blog/cleanroom-iso-7-certified
https://www.advancetecllc.com/classifications/iso-7-cleanroom-classification
Conclusion
ISO Class 7 cleanrooms have stringent requirements to maintain high levels of air cleanliness. Some key guidelines include:
- Maintaining particle counts below 352,000 particles of 0.5μm size per cubic meter of air.
- Controlled temperature of 68-73°F and relative humidity between 30-65%.
- Frequent air changes, at least 10-15 per hour.
- Positive pressure differential from less clean adjacent areas of at least 0.17 H2O column inches.
- Proper gowning procedures including masks, gloves, hairnets, hoods, coveralls, and shoe covers.
- Regular cleaning and disinfection using EPA approved products.
- Use of smooth, non-particle shedding construction materials.
- Annual re-certification to ISO standards.
By following these specifications, ISO Class 7 cleanrooms provide a highly controlled environment for critical manufacturing and research applications.
