Fujitsu fi-4120C Operator's Manual page 21

Protect the scanner from static electricity.
Do not use aerosol sprays near the scanner.
Avoid any contact when scanner is in use.
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Install the scanner away from strong magnetic fields
and other sources of noise. Also, protect the scanner
from static electricity as this might cause the
scanner to malfunction.
Do not use aerosol sprays, for example, to clean the
scanner. Air sprayed from aerosol sprays causes dirt
and dust to enter the scanner, resulting scanner
failure and malfunction.
Avoid any contact when scanner is operating as this
may cause injuries.