A clean room must meet the standards of the International Organization of Standardization (ISO) in order to be classified. The ISO, founded in 1947, was established in order to implement international standards for sensitive aspects of scientific research and business practices, such as working with chemicals, volatile materials, and sensitive instruments. Though the organization was created voluntarily, the standards established have set foundational principles in place that are honored by organizations worldwide. Today, the ISO has over 20,000 standards for companies to use as a guide.
The first clean room was developed and designed by Willis Whitfield in 1960. The design and purpose of a clean room is to protect its processes and contents from any outside environmental factors. The people who use the room and the items that are tested or constructed in it may hinder a clean room from meeting its standards of cleanliness. Special controls are required to eliminate these problematic elements as much as possible.
A clean room classification measures the level of cleanliness by calculating the size and quantity of particles per cubic volume of air. The units begin at ISO 1 and go to ISO 9, with ISO 1 being the highest level of cleanliness while ISO 9 is the dirtiest. Most clean rooms fall into the ISO 7 or 8 range.
International Organization of Standardization Particulate Standards
|
Class |
Maximum Particles/m3 |
FED STD 209E Equivalent |
|||||
|
>=0.1 µm |
>=0.2 µm |
>=0.3 µm |
>=0.5 µm |
>=1 µm |
>=5 µm |
||
|
ISO 1 |
10 |
2 |
|||||
|
ISO 2 |
100 |
24 |
10 |
4 |
|||
|
ISO 3 |
1,000 |
237 |
102 |
35 |
8 |
Class 1 |
|
|
ISO 4 |
10,000 |
2,370 |
1,020 |
352 |
83 |
Class 10 |
|
|
ISO 5 |
100,000 |
23,700 |
10,200 |
3,520 |
832 |
29 |
Class 100 |
|
ISO 6 |
1,000,000 |
237,000 |
102,000 |
35,200 |
8,320 |
293 |
Class 1,000 |
|
ISO 7 |
352,000 |
83,200 |
2,930 |
Class 10,000 |
|||
|
ISO 8 |
3,520,000 |
832,000 |
29,300 |
Class 100,000 |
|||
|
ISO 9 |
35,200,000 |
8,320,000 |
293,000 |
Room Air |
|||
Federal Standards 209 E – Clean Room Standards Classifications
|
Maximum Particles/m3 |
|||||
|
Class |
>=0.5 µm |
>=1 µm |
>=5 µm |
>=10 µm |
>=25 µm |
|
Class 1 |
3,000 |
0 |
0 |
0 |
|
|
Class 2 |
300,000 |
2,000 |
30 |
||
|
Class 3 |
1,000,000 |
20,000 |
4,000 |
300 |
|
|
Class 4 |
20,000 |
40,000 |
4,000 |
||
How to keep a clean room classification
Since the purpose of a clean room is to study or work on delicate and fragile components, it would seem very unlikely that a contaminated item would be inserted into such an environment. However, there is always a risk, and steps must be taken to control it.
There are two variables that can lower a clean room’s classification. The first variable is the people who use the room. The second is the items or materials that are brought into it. Regardless of the dedication of a clean room staff, errors are bound to happen. When in a hurry, people may forget to follow all of the protocols, wear inappropriate clothing, or neglect some other facet of personal care.
In an attempt to control these oversights, companies have requirements for the type of attire clean room staff must wear, which is affected by the required processes in the clean room. Normal clean room attire involves foot coverings, caps or hair nets, eye wear, gloves and a gown. The strictest standards stipulate the wearing of full-body suits that have a self-contained air supply that prevents the wearer for contaminating the clean room with their breath.
Problems of maintaining a clean room classification
The quality of the air circulating system in a clean room is the most significant problem related to maintaining a clean room classification. Even though a clean room has already received a classification, that classification can easily change or be lost altogether if it has a poor air filtration system. The system greatly depends on the number of filters required and the efficiency of their air flow.
One major factor to be considered is the cost, which is the most significant part of maintaining a clean room. In planning to build a clean room to a specific standard, manufacturers need to take a few things into consideration. The first item is the number of filters that are required to preserve the room’s air quality. The second item to consider is the air conditioning system to ensure that the temperature inside the clean room remains stable. Finally, the third item is the design of the room. In too many cases, companies will ask for a clean room that is larger or smaller than what they require. Therefore, the design of the clean room must be carefully analyzed so that it meets the exact requirements of its intended application.
What industries require the strictest clean room classifications?
As technology advances, there are crucial factors related to the production of technical devices. One of the major issues is the control of miniscule elements that may upset the operation of a sensitive device.
The most obvious need for a contaminate-free environment is the pharmaceutical industry where vapors or air pollutants could corrupt the manufacture of a medicine. Industries that produce intricate miniature circuits for precise instruments must be assured that the manufacturing and assembly is protected. These are only two of the many industries the use clean rooms. Others are aerospace, optics, and nanotechnology. Technical devices have become smaller and more sensitive than ever before, which is why clean rooms will continue to be a critical item in effective manufacturing and production.
Post time: Mar-29-2023