Toshiba Aquilion TSX-101A/I Series Site Planning Manual page 68

However, increasing humidity too much causes humidity hazard.
(Refer to figure A.1.2-1.)
10
8
6
4
Clean room
2
0
10 20
Figure A.1.2-1 The relation between relative humidity and relative hazard ratio
The above relationship indicates that the relative humidity for systems should be
controlled in the 50% to 55% range as far as possible.
2. Countermeasures using conductive materials
The above method (increasing relative humidity) is not always optimal because
humidity hazard may be caused. Therefore, preventive measures using conductive
materials are outlined below. (An example comparing conductive shoes with normal
shoes is presented.)
Walking in place
<2> Normal shoes
1500
1000
<1> IC shoes (conductive
500
0
Time (min)
Figure A.1.2-2 Nonconductive flooring
material
Figure A.1.2-2 illustrates an example of walking in place followed by standing on a
nonconductive floor with normal shoes and conductive shoes. (The static electricity
voltage may be higher depending on the material of the clothes, etc.) Wearing
conductive shoes makes it possible to decrease the static electricity voltage level.
However, the static electricity voltage even at this level could damage devices, as
shown in the table A.1.2-1.
55%
30 40 50 60
Relative humidity (%)
Standing
shoes)
1 2
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No. 2A201-519EN*A
Overall hazard ratio
Humidity hazard
Static electricity hazard
70 80 90 100
Walking in place
1500
1000
500
<2> Normal shoes
<1> IC shoes
(conductive shoes)
0
Time (min)
Figure A.1.2-3 Conductive flooring
material
Leakage hazard
Corrosion hazard
Annoyance hazard
Standing
1 2