Cleanroom Classifications Mean

Controlled Environments (CE): How are cleanroom classifications determined?

Patrick McGee (PM): As of November 2001, ISO 14644-1 supersedes the previous Federal Standard 209E as the international standard for cleanroom classifications. ISO cleanroom classifications are determined by how much particulate at a specific size (0.1 micron – 5 micron) are present per cubic meter in the cleanroom space. Classifications range from ISO 1 cleanest) to ISO 9 (dirtiest). As particulate levels change dependent on the activity in the cleanroom, these classification levels are tested at three different stages: as-built, at-rest, and operational. Classification is easiest to achieve at the “as-built” stage and becomes more difficult during the “operational” stage as people (the largest contaminate in a cleanroom) are added. For clients to determine the classification of cleanroom they need, they must first define their process and the particulate size and levels they are looking to regulate.

CE: What are common federal/global standards that cleanroom companies must adhere to when manufacturing cleanroom products and components?

PM: Cleanroom products must be manufactured to be non-shedding and have a cleanable surface. Manufacturers should be ISO 9001 certified, resulting in internal audits to ensure quality is being monitored. ISO 9001 quality management systems (QMS) standards are designed to ensure that companies meet the needs of their customers while meeting regulatory requirements related to a product.

CE: How do you guide clients who need specific accommodations for their cleanrooms?

PM: Despite the guidelines of ISO classifications, typically each customer’s cleanroom needs are dependent on what process they are doing in the room and what size particulate is causing problems for the client. Therefore, you must first address both what you are doing in the room and what you are trying to keep out before you can design the room itself.

CE: Are there any components/products that will work in all kinds of cleanrooms, or must the products be specific to each classification level?

PM: As previously mentioned, ISO classifications are measured by the number and size of particulates in the room. One way these classifications are achieved is through the Air-Change Rate, or ACR. The ACR is the number of times each hour that filtered outside air replaces the existing air volume in the room(s). This turnover in air allows for particulates to be filtered out of the room. In many cleanrooms the ACR is achieved using Fan/Filter units (FFUs). FFUs are a component that will work in all kinds of cleanrooms. The largest factor that will change between classification levels is the number of FFUs. Similar to FFUs many components and products are capable of working in cleanrooms of differing classifications such as cleanroom wall materials, ceiling materials, and pass-throughs.

Although these components may be the same for differing classifications, they may change dependent on the process in the room. For example, a medical device ISO 7 would be okay with standard vinyl faced cleanroom ceiling tiles and fiberglass reinforced plastic (FRP) wall panels, while a semiconductor ISO 7 cleanroom would require a metal faced panel with static dissipative finish that is non-sheading and non-out gassing. These differing requirements are met through implementing different envelopes based on the client’s process.

CE: What’s new and exciting in the world of cleanroom classifications? Any new standards or products that people should be aware of?

PM: As technology increases and product yield can be easily tracked, more and more companies are moving towards operating their manufacturing processes in a cleanroom. With the ISO regulations came the designation of ISO 9, which was not previously a cleanroom classification. An ISO 9 translates roughly into a “controlled and classified area,” as defined by the pharmaceutical industry. This classification means that the particulate level, temperature, and humidity are all controlled but the room is not classified in terms of particle count. In many cases, this is all a client needs. Products to achieve these environments have changed as more people are moving towards self-supportive envelopes. In an effort to not disrupt the existing area, people are utilizing structural envelopes that can support a plenum system as well as additional mechanical systems. By utilizing self-supporting envelopes, clients do not need to tie into their existing structure streamlining the process.

CE: How do you deal with non-U.S. clients? Do cleanroom standards vary in different parts of the world?

PM: While ISO 14644-1 act as the international standards, there are different requirements in certain parts of the world for cleanrooms in certain industries. In Europe, for example, the Good Manufacturing Practice (GMP) for the pharmaceutical practice designates areas A, B, C, and D — with A being the most critical and D being for the less critical stages of manufacturing. These guidelines are now followed in both the U.S. and Europe. Be it with U.S. or international clients, it is crucial to first address the process and need for the cleanroom to then design accordingly.

CE: Are there any materials or products that were once common but are no longer able to be used in cleanroom construction?

PM: Metal studs and drywall, as used in conventional construction, are being used less in cleanroom construction as the use of modular components are increasing. Modular construction utilizes pre-fabricated materials which can be installed in already clean environments with a quicker and no-mess installation.

CE: What happens if a client’s cleanroom does not meet the proper classification standards? Is a total tear-down necessary, or can minor adjustments be implemented to save it?

PM: Refitting a cleanroom needs to be looked at on a case-by-case basis. On occasion, it could be as simple as adding additional FFUs — other times, a complete repurpose of the room may be necessary. Rooms can be refit utilizing a new cleanroom ceiling grid and liner panels that clad directly to existing walls to create a cleanable, non-shedding surface. But the existing mechanical system could cause limitations. Although most rooms could be worked to fit an ISO standard, it, at times, may be more practical to build out a new space rather than utilizing existing.

CE: How does cleanroom classification affect the cost?

PM: Each transition from one ISO class to another results in a dramatic difference in the amount of air required. For example, if you are switching from an ISO 8 to an ISO 7, the room will require twice as much air. The filtering and moving of air in your cleanroom is a significant operating cost. The “simple” switch from an ISO 8 to an ISO 7 classification could result in almost a 25 percent increase in price for the same size room. Thus, it is always important to address on the front end what particulates are a concern in your cleanroom.