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Clean Room Technology Then And Now


The principle of Clean room design starts from almost 150 years ago when these units were used for bacterial control in hospitals. Today, clean rooms have completed a long way and developed to the modern technology. In earlier day, these clean rooms were designed for fulfilling the requirement of clean environment for industrial manufacturing during 1950s and the same clean rooms are also used for variety of applications in many industries.

A clean room is defined as a place that provides attentively controlled environment that has a low level of environmental pollutants such as airborne microbes, dust, chemical vapors, and aerosol particles. When the air entered in a clean room it is filtered and then continuously circulated through high efficiency particulate air (HEPA) or ultra-low particulate air (ULPA) filters. These filters are used to remove internally generated contaminants. The persons, who work inside the clean room, wear protective clothing while enter and exit through airlocks, while equipment and furniture inside the clean room is specially designed to produce minimal particles.

Today, more than 30 different industry segments utilize clean rooms including semiconductor and other electronic components, pharmaceutical, and biotechnology industries.

Modern clean rooms were developed during the Second World War to improve the quality and reliability of instrumentation used in manufacturing guns, tanks and aircraft. During this time, HEPA filters were also developed to contain the dangerous radioactive, microbial or chemical contaminants that resulted from experiments into nuclear fission, as well as research into chemical and biological warfare.

On the other hand, clean rooms for manufacturing and military purposes were being developed; the importance of ventilation for contamination control in hospitals was being realized. The use of ventilation in a medical setting gradually became standard practice during this time.

The concept of laminar flow' was introduced during 1950s and 1960s, when NASA's space travel program was initiated. This marked a turning point in clean room technology and from this time, the evolution of clean rooms gained momentum.

In the late 1950s, the Sandia Corporation (which later became Sandia National Laboratories) began investigating the excessive contamination levels found in clean rooms. Researchers found that clean rooms were being operated at the upper practical limits of cleanliness levels and identified a need to develop alternative clean room designs.

In 1961, Professor Sir John Charnley and Hugh Howorth, showed a tremendous improvement in unidirectional airflow by creating a downward flow of air from a much smaller area of the ceiling, directly over the operating table.

Also in 1961, the first standard written for clean rooms, known as Technical Manual TO 00-25-203, was published by the United States Air Force. This standard considered clean room design and airborne particle standards, as well as procedures for entry, clothing and cleaning.

In 1962, Patent No. 3158457 for the laminar flow room was issued. It was known as an "ultra clean room."

By 1965, there have been several vertical down flow rooms were used in which the air flow ranged between 15 m (50 ft)/min and 30 m (100 ft)/min. It was during this time that the specification of 0.46 m/s air velocity and the requirement for 20 air changes an hour became the accepted standard.

By the early 1970s the principle of "laminar flow" had been translated from the laboratory to wide application in production and manufacturing processes.

The 1980s saw continued interest in the development of the clean room. By this stage, clean room technology had also become of particular interest to food manufacturers.

In 1987, a patent was filed for a system of partitioning the clean room to allow zones of particularly high-level cleanliness. This improved the efficiency of individual clean rooms by allowing areas to adopt different degrees of cleanliness according to the location and need.