Siemens SIMATIC Series Operating Instructions Manual page 106

Device maintenance and repair
7.2 Maintenance
Note
Use of the filter pad
We advise against using filter pads that have already been used. If you do want to refit a
filter pad you have removed, however, take account of the direction in which the fan draws
air into the device. Make absolutely certain that you do not fit the outer side of the filter pad
on the inside. Generally, the outer side is clearly dirty after it has been in use for some time.
106
Operating Instructions, 04/2020, A5E49948632-AA
SIMATIC IPC547G