无尘室等级如何定义
无尘室的等级说明
使用者在开无尘室的等级给供货商时，有以下几个小技巧。
首先是等级定义的模式如下：
Class X (at Y μm )
其中X是无尘室的等级，例如100或10000等等，Y是粒径如0.2μm , 0.5μm等，可复选。意思就是使用者规定，该无尘室微粒含量，在这些粒径必须满足该等级的限度。这样可以减少纷争，以下是几个例子：
Class1 (0.1μm, 0.2μm , 0.5μm)
Class 100(0.2μm , 0.5μm )
Class 100(0.1μm, 0.2μm , 0.5μm )
在Classes 100 (M3.5) and Greater (Class 100，1000，10000….)，一般看一个粒径即可。在Classes Less than 100 (M3.5) (Class 10，1…. )，一般要看多几个粒径。
第二个技巧是规定无尘室的状态，例如：
Class X (at Y μm )，At-rest
供货商就很清楚知道无尘室要在At-rest状态下验收。
第三个技巧是自订微粒浓度上限，一般在As-built时无尘室都很干净，微粒控制能力测试不易，这时可以干脆把验收上限压低，例如：
Class 10000 (0.3 μm <= 10000)，As-built
Class 10000 (0.5 μm <= 1000)，As-built
这样做的目的是确保无尘室在Operational状态时，依然有足够的微粒控制能力。
以下两个表是Fed-Std-209E的等级定义，和ISO-14644的等级定义。
|
Class Name
|
Class Limits | ||||||||||
| 0.1μm | 0.2μm | 0.3μm | 0.5μm | 5μm | |||||||
| Volume Units | Volume Units | Volume Units | Volume Units | Volume Units | |||||||
| SI | U.S. | (m3) | (ft3) | (m3) | (ft3) | (m3) | (ft3) | (m3) | (ft3) | (m3) | (ft3) |
| M 1 | 350 | 9.91 | 75.7 | 2.14 | 30.9 | 0.875 | 10.0 | 0.283 | – | – | |
| M 1.5 | 1 | 1,240 | 35.0 | 265 | 7.50 | 106 | 3.00 | 35.3 | 1.00 | – | – |
| M 2 | 3,500 | 99.1 | 757 | 21.4 | 309 | 8.75 | 100 | 2.83 | – | – | |
| M 2.5 | 10 | 12,400 | 350 | 2,650 | 75.0 | 1,060 | 30.0 | 353 | 10.0 | – | – |
| M 3 | 35,000 | 991 | 7,570 | 214 | 3,090 | 87.5 | 1,000 | 28.3 | – | – | |
| M 3.5 | 100 | – | – | 26,500 | 750 | 10,600 | 300 | 3,530 | 100 | – | – |
| M 4 | – | – | 75,700 | 2140 | 30,900 | 875 | 10,000 | 283 | – | – | |
| M 4.5 | 1,000 | – | – | – | – | – | – | 35,300 | 1,000 | 247 | 7.00 |
| M 5 | – | – | – | – | – | – | 100,000 | 2,830 | 618 | 17.5 | |
| M 5.5 | 10,000 | – | – | – | – | – | – | 353,000 | 10,000 | 2,470 | 70.0 |
| M 6 | – | – | – | – | – | – | 1,000,000 | 28,300 | 6,180 | 175 | |
| M 6.5 | 100,000 | – | – | – | – | – | – | 3,530,000 | 100,000 | 24,700 | 700 |
| M 7 | – | – | – | – | – | – | 10,000,000 | 283,000 | 61,800 | 1,750 | |
| ISO classification number(N) | Maximum concentration limits (particles/m3of air) for particles equal to and larger than the considered sizes shown below (concentration limits are calculated in accordance with equation (1). | |||||
| 0.1mm | 0.2mm | 0.3mm | 0.5mm | 1mm | 5mm | |
| 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 | 83 | |
| 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 requires that concentration data with no more then three significant figures be used in determining the classification level.
Equation (1): Cn = 10NX (0.1/D)2.08其中Cn是微粒浓度，N是洁净度，D是粒径 |
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比较以上两表我们可看出
