What is a Cleanroom, anyway?

When people ask what I do for work, I tell them I build cleanrooms. With very few exceptions, people always ask what a cleanroom is! Technically speaking, a cleanroom is a room where specific size and amounts of particulate in the air is filtered out of the ambient air stream. Not-so-technically—it’s a room with the purest air quality possible in it. There are many other factors involved in creating cleanrooms, depending on the industry. Things like temperature, humidity, light, sound, and vibration, all need to be regulated for those in need of a cleanroom.

In its most basic form, though, a cleanroom is about minimizing the particulate (tiny particles of matter) in the air. The need to remove particulate is most often related to the quality of the end product being created manufactured. We keep the good stuff (electronics, pharmaceuticals, scientific research) all free and clear of the bad stuff (pollutants, dust, airborne microbes, aerosol particles, chemical vapors). And we do it all in a neat, controlled environment.

Using physical testing of product defects and regulatory requirements, most organizations that use cleanrooms are able to determine just how clean they need their room. Currently, cleanrooms are classified by ISO 14644 (a system) from the extremely clean “ISO Level 1” to the less clean “ISO Level 8”. Check out this chart for a visual of the scale:

When a cleanroom is complete, it is normally certified to the ISO standard, to prove that the room works as required. The room has to function in three different states:

  1. At Rest – an empty room to prove the design worked
  2. As Built – a room with equipment, no people, and not operating
  3. Operational – a room with people in, that is operating.

This is the trickiest certification as knowledge of the process, gowning, and cleaning procedures need to be given to the designers before the room is even designed and built. There is a high level of forethought put into every cleanroom project, from concept to execution, in order to avoid contamination and defective product.

The real key to building a cleanroom and keeping, well…clean, is building with non-particulating products for the wall, floors, ceiling, and mechanical systems. Once you establish the level of cleanliness you wish to accomplish, you can research and choose the products that will insure that the room does not particulate. This is coupled with the design of the HVAC equipment and systems using non-particulating products and proper filtration of both the recirculated air and the outside air.

Typically, most cleanroom recirculation systems have two levels of filtration including a pre-filter, usually Merv 7 or higher and a HEPA or ULPA filter. Outside air is normally filtered two or three levels with a Merv 8, a 95% filter (MERV 14), and a HEPA filter with three step system. Outside units may also contain charcoal filters to help keep out hydrocarbons. The outside air picks up particulate like dust, pollen, etc. Inside air, though, is normally only exposed to the process equipment and to people. Most process in cleanrooms tends to not produce a lot of particulate, but the people do! Therefore, the gowning and cleaning procedures are of the utmost importance to maintain the cleanroom.

Over the years, we have seen that continuous cleaning once the non-shedding perimeter of a cleanroom is established is a key to the long-term success of a cleanroom. Removing as much particulate as possible before a cleanroom goes online and “building clean” prevents particles from coming free in the future and causing particle problems.

A cleanroom requires filtration of air inside the room and from outside the room, cleaning during construction and after, building with non shedding material, control of people and gowning as well as material in and out, to insure the cleanroom meets its specified performance. Many cleanrooms are built with a 4-level Cleanroom Protocol Program to increase the cleanliness. The list of requirements grows as the room is being completed.

Stay tuned to the blogs and we’ll detail why and how these programs are designed. We’ll also give you some insight into how we implement them here at Hodess Cleanroom Construction.

For now, any questions?

Erika Hodess
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