Cleanrooms are special areas or indoor environments constructed by strict regulations. In these areas the occurrence of particles and contamination, the air temperature, the humidity and the pressure ratio are regulated by strict standards. In the air of cleanrooms the allowed maximum occurrence of tenth of a micron and submicron particles are specified too. The main job of a cleanroom is to regulate the number of particles and to keep it on the permitted levels.
Cleanrooms are mostly used in precision mechanics, pharmaceuticals, automobile industry, equipment manufacturing, space technology and other industries, where it is important to maximize the occurrence of particles in the air. In the latest trends the benefits of cleanroom manufacturing is not only known in medical technology, but in laser research and in the food industry too.
Why do we control air?
The reason for this differs from industry to industry. Most of the times the goal is creating a product that is protected of the pollution in the air. For example no one would like to find small particles or dirt behind the screen of their newly purchased phone. But apart from quality assurance there are several other uses of cleanrooms. In the pharmaceutical industry and microbiology it is crucially important to preserve sterility. But in laboratories the main purpose is to prevent the properties of the tested samples from being impacted by anything unnecessary.
US FED STD 209E
The oldest standard, that has been withdrawn, is the American US FED STD 209E standard. However up until today many multinational company is still specify their requirements based on the values of the FED209E standard.
|≥0.1 µm||≥0.2 µm||≥0.3 µm||≥0.5 µm||≥5 µm|
The ISO 14644-1 is the most common, and most modern clean-air standard. It not only specifies the design of cleanrooms, but also the directives for the construction and the methods of usage too. Many manufacturers define their requirements according to the ISO-14644 standard:
|Class||maximum particles/m3 a||FED STD 209E
|≥0.1 µm||≥0.2 µm||≥0.3 µm||≥0.5 µm||≥1 µm||≥5 µm|
|ISO 3||1,000||237||102||35b||d||e||Class 1|
|ISO 4||10,000||2,370||1,020||352||83b||e||Class 10|
|ISO 5||100,000||23,700||10,200||3,520||832||d,e,f||Class 100|
|ISO 6||1,000,000||237,000||102,000||35,200||8,320||293||Class 1,000|
|ISO 7||c||c||c||352,000||83,200||2,930||Class 10,000|
|ISO 8||c||c||c||3,520,000||832,000||29,300||Class 100,000|
|ISO 9||c||c||c||35,200,000||8,320,000||293,000||Room air|
a All concentrations in the table are cumulative, e.g. for ISO Class 5, the 10 200 particles shown at 0,3 μm include all particles equal to and greater than this size.
b These concentrations will lead to large air sample volumes for classification. Sequential sampling procedure may be applied; see Annex D.
c Concentration limits are not applicable in this region of the table due to very high particle concentration.
d Sampling and statistical limitations for particles in low concentrations make classification inappropriate.
e Sample collection limitations for both particles in low concentrations and sizes greater than 1 μm make classification at this particle size inappropriate, due to potential particle losses in the sampling system.
f In order to specify this particle size in association with ISO Class 5, the macroparticle descriptor M may be adapted and used in conjunction with at least one other particle size.
The guidelines of the GMP are probably the strictest. It requires a qualification procedure during operation. Meaning it examines the quality of the cleanroom during the application of methods and procedures used in the manufacturing process. Cleanroom standards don’t only prescribe cleanroom requirements based on the number of particles. Properly designed and built cleanrooms take air exchange rates into account in order to stay within the limits. They also pay attention to the surfaces of the required outlet and extraction points, the cover of these points and the direction of the convections.
|At Rest||In Operation|
|0.5 µm||5 µm||0.5 µm||5 µm|
|Grade D||3,520,000||29,000||Not defined||Not defined|
Cleanroom standards therefore include such complex technological directives that help creating a unique cleanroom environment specified for the given industry.
Our company usually qualifies our complex cleanrooms in the as-built stage with accredited institutions, to classify them as cleanrooms. No cleanrooms can be established without qualification and continuous validation. Therefore, our advice for investors is to qualify the cleanroom with a third party institution.