The Modern Clean Room – How It’s Made & What Happens Inside?
Throughout their short history cleanrooms have had a fascinating progression from theory to reality. The idea of contamination control transitioned fairly quickly from strictly medical use to the varied research and manufacturing we see today. Within a few years of its commercial creation, the modular cleanroom would generate 50 billion dollars in sales, but how did the industry get here? There have been several interesting developments throughout the process. For example, did you know the HEPA filter was a product created as a result of the Manhattan Project? In this blog post we intend to explore this bit of history and more, starting with a look at how contamination control has changed throughout time. We’ll even explore some of the modern uses for cleanrooms – an industry that’s only been around for the last 60 or so years.
A Cleanroom (or clean room) is a controllable environment that allows a tiny percentage of particles in the air to enter a room. They are used in manufacturing and research industries such as electronics, pharmaceuticals, biopharmaceuticals, and even medical devices. For perspective, a typical urban environment has around 35,000,000 particles per cubic meter in the range of .05µm + in diameter. An ISO 1 room – the cleanest of the clean – allows only 12 particles per cubic meter of 0.3µm and smaller. For each increase in ISO number, there is a parallel 10x increase in the particles allowed. Most cleanrooms for manufacturing are class ISO 2 or ISO 3 – with ISO 9 being similar to a normal room, but cleaner. A cleanroom continuously works to maintain a low level of contaminants; such as dust, airborne microbes, unwanted particles, or chemical vapors. The actual amount and purpose varies between types of classification of the room or sector using it. For example, the pharmaceutical industry requires their rooms remain strictly moisture free, but the technology sector is concerned with preventing or limiting airborne contaminants. Regardless of the industry, the main purpose for a cleanroom is to establish total control of an environment and prevent exposure to bacteria that may disrupt work or research. This means controlling the air flow rate, direction, temperature, pressurization, and humidity – all in the name of contamination control.
In the beginning there was Louis Pasteur – a French chemist known for his discoveries in the field of microbiology. Pasteur is responsible for the principles for vaccination, pasteurization, and for the first vaccines for rabies and anthrax. He was the first to discover the significance between the world’s smallest particles (microorganisms) and their effects on people. It was Louis Pasteur who discovered that bacteria are responsible for the souring of drinks and meats. His work also provided direct support to the Germ Theory of Disease, which states that some diseases are caused by microorganisms. Pasteur tested and proved that controlling these organisms would enable us to control infection and prevent contamination, but British surgeon, Joseph Lister, was the first to demonstrate the practical applications of Germ Theory. Lister was the first to practice the theory by experimenting with antiseptics during surgery. Lister was the first to introduce carbolic acid to wounds to clean them. He also implemented this in his cleaning procedures for his equipment, and was the first surgeon to notice that washing his hands lowered the risk of infection for the patient. This became the first step in creating a contaminant free environment; however Lister only created and incorporated anti-septic sprays into his surgical practices for a brief period – from 1883 to 1897. While progressive for the time, his methods didn’t prevent airborne particles from entering or infecting an area.
Image via Wikipedia
One of the key ingredients of a cleanroom came into existence during the 1940’s under a classified project, funded by the government, in part of the Manhattan Project. The HEPA (High Efficiency Particulate Air) Filter was created during the race for the atomic bomb. The idea was to keep engineers safe from potentially harmful radiation. It didn’t accomplish that goal, but the HEPA filter does remove 99.97% of 0.3 µm (micrometers) particles. These particles can detected by using particle detectors link. The 0.3 µm size represents the Most Penetrating Particle Size (MPPS), which is the most difficult size of particle to filter out. This is also the United States standard for filters allowed to operate in clean rooms. An interesting note about the HEPA filter is that it blocks fine particles effectively, but does not filter out gasses or odor molecules. As well, only in particular circumstances which require the filtration of particular substances (chemical vapors, cigarette or pet odors, or volatile organic compounds), is activated carbon (charcoal) used instead of / in addition to the HEPA filter. However, ULPA (Ultra-low particulate air) filters can remove at least 99.999% of dust, pollen, mold, or bacteria from the air. It can remove any airborne particle with a size of 100 nanometers (0.1 µm) or larger. These are occasionally used in combination with the HEPA filter – particularly in the pharmaceutical industry due to their strict requirements on moisture within the working environment. Following the break through creation of the HEPA filter the next challenge was to obtain full control of an environment. Air conditioning and room pressurization became considered essential in the effort to control the air flow of a room, and thus they were implemented, but it wouldn’t be until the 1960’s for full environmental control to be possible. This came as a direct result of physicist Willis Whitfield’s design for the modern clean room. The heart of its success was that it controlled the previously unpredictable direction of air flow within a room. Whitfield’s design maintained constant and highly filtered air flow, which served to flush out impurities. Within a few years this breakthrough would generate upwards of $50 billion in sales throughout the world, as well as set the stage for the next evolution in technology. What was crucial about Whitfield’s design is, as mentioned, the idea of full air control. In the Whitfield cleanroom, when air enters the cleanroom, it is first filtered to exclude dust, smoke, or any other pollutant. Then air is continuously recirculated through the HEPA Fan in either laminar air flow patterns or turbulent air flow patterns, all aimed at removing internally generated contaminants. This all shifted the focus from what was already in the room to what was entering the room. Once mastery of the environment had been achieved, cleanroom garments and protective clothing were introduced to manage the human element. These items range from gloves, masks, and beard covers to full body suits. As the demand for cleaner and more protected rooms increased, air showers, personnel cleaning equipment, and other methods to further prevent contamination were implemented. These developments led to a several step procedure of how to properly enter the environment.
Where are they used? (Cleanrooms Power Everything)
Having a near pollutant free room allows for a world of full of advancements in the fields of scientific research or manufacturing. One of the most famous cleanrooms is NASA’s Goddard Space Flight Center in Greenbelt, Maryland, contains the world’s largest ISO 7 cleanroom – known as The High Bay Cleanroom, with 1.3 million cubic feet of space. This enormous space was the engineering bay for the Hubble telescope – as well as the soon to be launched James Webb Telescope. Telescopes and satellites aren’t all that’s made in a cleanroom environment. Most of the components that make up your smartphone, your computer, or your car, were also made in one of these marvels of technology. Virtually all medicines are created in a cleanroom and most scientific research happens within some level of controlled environment. Everything you can see or think of that represents technology was, at one point, developed within the confines of a cleanroom. The concept of a pollutant, or contaminate, free environment is crucial to the way that we live and for us to advance in the future. When considering what takes place inside a facility, it becomes very easy to see why the modular cleanroom is so important and prevalent.
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