5 Principles of Clean Room
Clean air inflow into Clean Room
Maintaining required emperature, humidity and indoor pressure in Clean Room
Preventing inflow of corpuscles into Clean Room
Preventing creation of corpuscles in Clean Room
Prompt elimination of accumulation of corpuscles in Clean Room
DEFINITION of CLEAN ROOM
SIZE OF PARTICLES IN THE AIR
The particles floating in the air are very small materials including not only small parts of sand particles, metal dust, human skin’s dust, and smoke but also microorganisms such as bacteria, virus, and mold. The size of the particles widely ranges from 0.001㎛ to 100㎛, about 106 in the air.
In particular, in large cities with air pollution, there are approximately 300million particles of more than 0.5㎛ in the air of 1㎥(35.35ft3) The size of particles in the air is shown in the Figure below.
CLASSIFICATION OF PARTICLE SIZE IN THE AIR
THE SIZE COMPARED WITH THE THICKNESS OF THE HAIR OF HUMAN BEING (100㎛)
SIZE of CLEAN ROOM
The standard related to clean room includes KS and JIS. However, generally, National Aeronautics and Space Administration standard (NASA NHB 5340.2) had been used widely universally to American federation standard (U.S Fed, Std. 209D) and BCR (Bio clean room) to ICR (Industrial clean room), but was integrated at present to ISO 14644-1.
ISO Classification number(N) | Maximum concentration limits (Particles/㎥ of air) for particle equal to and larger than the considered size shown below |
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0.1㎛ | 0.2㎛ | 0.3㎛ | 0.5㎛ | 1㎛ | 5㎛ | |
ISO Class 1 | 10 | 2 | - | - | - | - |
ISO Class 2 | 100 | 24 | 10 | 4 | - | - |
ISO Class 3 | 1,000 | 237 | 102 | 35 | 8 | - |
ISO Class 4 | 10,000 | 2,370 | 1,020 | 352 | 82 | - |
ISO Class 5 | 100,000 | 23,700 | 10,200 | 3,520 | 832 | 29 |
ISO Class 6 | 1,000,000 | 237,000 | 102,000 | 35,200 | 8,320 | 293 |
ISO Class 7 | 352,000 | 83,200 | 2,930 | |||
ISO Class 8 | 3,520,000 | 832,000 | 29,300 | |||
ISO Class 9 | 35,200,000 | 8,320,000 | 293,000 | |||
Note. Uncertainties related to the measurement process require that concentration data with no more than three significant figures be used in determining the classification level |
OUTLINE OF NASA NHB 5340.2
(NASA standard (NHB 5340.2))
BIO Clanroom Class | Particle | Virus | ||
Size | ft3(ℓ) No, of accumulated particles | ft3 (ℓ) Floating amount | ft3 (ℓ) Sediment amount |
|
100 | ≥0.5 | ≤100(≤3.5) | ≤0.1(0.0035) | 1,200(12,900) |
10,000 | ≥0.5 | ≤10,000(≤350) | ≤0.5(9.9176) | 6,000(64,600) |
≥0.5 | ≤65(≤2.3) | |||
100,000 | ≥0.5 | ≤100,000(≤3,500) | ≤2.5(0.0884) | 30,000(323,000) |
≥5.0 | ≤700(≤25) |
THE U.S. FED. STANDARD
OUTLINE OF JIS B9920
Maximum concentration of cleanliness lass (units/㎥)
Size (㎛) | leanliness class | ||||||
Class 2 | Class 3 | Class 4 | Class 5 | Class 6 | Class 7 | Class 8 | |
0.1 | 102 | 103 | 104 | 105 | 106 | 107 | 108 |
0.2 | 24 | 236 | 2,360 | 23,600 | - | - | |
0.3 | 10 | 101 | 1,010 | 10,100 | 101,000 | 1,010,000 | 10,100,000 |
0.5 | (3.5) | 35 | 350 | 3,500 | 35,000 | 350,000 | 3,500,000 |
5.0 | - | - | - | - | 29 | 2,900 | 29,000 |
Cleanliness class size range | 0.1~0.5 | 0.1~0.5 | 0.3~5.0 |
KS STANDARD
CLASSIFICATION OF CLEAN ROOM
Clean room is classified into three types depending on the air current method like the following.
CLASS : 1~1,000
VERTICAL STREAMLINE TYPE CLEAN ROOM
The highly effective filter is attached to the ceiling and a lattice plane is installed to the floor for the whole surface intake and vertical flow of clean air. Floating corpuscles created indoors flow to the downstream and do not affect the surrounding area. Therefore, it is possible to realize Class 100 in a super clean space Class 1.
The velocity of the wind carried-out is approximately 0.23~0.5m/sec.
CLASS : 100~1,000
HORIZONTAL STREAMLINE FLOW CLEAN ROOM
In the entire wall on one side, a highly effective filter is installed to suck in the air from the entire wall on the opposite side for the horizontal flow of clean air. Due to the work influence from the upper stream part, the cleanliness in the downstream part is decreased and the velocity of the wind carried-out is 45m/sec or more.
CLASS : 1,000~10,000
NON-STREAMLINE FLOW TYPE CLEAN ROOM
It installs a highly effective filter to a general H.V.A.C system facility’s diffuser. Clean air dilutes the indoor pollutants and increase the degree of cleanliness.
CLEAN ROOM SYSTEM AREA AND CLEANLINESS
Clean room is classified into three types depending on the air current method like the following.