Cleanrooms are generally buildings that are designed for conducting sensitive scientific research or handling and manufacturing products that require uncontaminated environments. Usually cleanrooms use a variety of mechanisms, design features, and safe guards to prevent foreign particles, bacteria, and other similar contaminants from entering the workspace. Special employee uniforms and washing habits, separate sealed chamber and locker anterooms, and rigorous cleaning techniques with special materials and solvents are among these measures. In addition to those measures, one of the major factors keeping a cleanroom free from outside contamination is the integrated air filter system. Clean rooms can employ varying types of filters, such as HEPA and ULPA filters; these filters generally employ airflow principles such as laminar and turbulent airflow principles.

Cleanroom Basics

Clean rooms are used for sensitive scientific research that requires uncontaminated environments that are free from outside particles and bacteria. For example, when scientists grow cultures, it is important to isolate the task from foreign bacteria so that results will not be compromised. When it comes to manufacturing various kinds of products like microprocessors, the workspace needs to be a particle-free environment, because even a bit of dust contaminating the small chips of a microprocessor can compromise the product.

Cleanrooms come in several forms. These forms are usually divided into hard walled and soft walled. A hard wall clean room is a permanent structure or part of a larger permanent structure and generally doesn’t go anywhere. A soft wall cleanroom can be rearranged, expanded, or even transported depending on task requirements. Soft wall clean rooms are usually built within a larger, permanent structure. Soft wall cleanrooms (which are usually modular in design) are generally useful for medical emergencies or when requiring smaller scale, shorter timeframe manufacturing projects due to their flexible nature.

Cleanrooms are classified according to the amount of particles present in the air. There are two different standards used for these classifications depending on their use: the ISO classification and United States classifications specified by federal standards. ISO grades are numbers that correspond to factors of ten, starting from 1. A cleanroom graded ISO 1 contains ten or fewer particles per 0.1 micrometer cubed area; a cleanroom graded ISO 2 contains 100 or fewer particles per 0.1 micrometer cubed area; and so on. US federal standards are numbered 10, 100, 1000, etc., with each class specifying how many particles are in a 0.5 micrometer cubic area. Class 1 cleanrooms have one or fewer particles per 0.5 micrometer cubed area. Class 10 cleanrooms have 10 or fewer particles per 0.5 micrometer cubed area.

In order to limit the amount of particles they track into the cleanroom or particles they shed while working in the environment, workers are usually required to follow dress and cleanliness guidelines. Workers change into specially designed outfits, often with hood coverings, gloves, and breathing masks to keep the head covered. Workers also enter through an air shower to eliminate any lingering particles and then pass items into the cleanroom through a small antechamber that prevents outside air from entering the clean environment. Shoe scrubbers can also be used to prevent tracking in more particles.

Cleanroom Air Filtration

Clean rooms employ unique cleanroom-specific air filtration to limit the particles in the environment air. Typically, this is through the use of either a highly efficient particulate air (HEPA) or ultra low particulate air (ULPA) filter. These filters can remove roughly 99.9 percent of all micro particles in the air by applying either laminar air flow techniques or turbulent air flow techniques to the environment air.

Laminar air flow consists of air that flows in a straight path. Unidirectional air flow is maintained in clean rooms through the use of specialized laminar air flow hoods that direct air jets downward in a straight path, as well as cleanroom architecture that ensures turbulence is lessened, such as smooth surfaces and streamlined design. Laminar air flow utilizes HEPA filters to filter the air in the environment. Laminar filters are often composed of stainless steel or other non-shed materials to ensure the amount of particles that enter the facility remains low. Cleanrooms employing laminar air flow are generally known as Unidirectional Airflow Cleanrooms.

Non-unidirectional airflow clean rooms utilize turbulent airflow systems to clean air of particulates and maintain a clean environment. The entire enclosure is designed to use laminar flow and random, non-specific velocity filters to keep the air particle-free. Turbulent airflow can cause particle movement that can be difficult to separate from the rest of the air, but non-unidirectional airflow systems count on this random movement to move particles from the air through the filter.

See References

Air-Flow Principles

Class 10-100,000 Cleanrooms

Cleanrooms & Critical Environments Main

ICE Walls = Integrated Critical Environments