Cleaning the backflow preventer/shut-off device

The backflow preventer (ER-AP) or shutter with shut-off device against fire transmission (ER-APB) must be checked for proper functioning of the shutter and for soiling during the regular inspection.

  1. After removing the fan insert, check that the shutter moves easily and closes automatically.
  2. (ER-AP) If the fan insert is excessively soiled, the backflow preventer can be removed from the exhaust socket, checked for soiling and cleaned if necessary.
  3. (ER-APB) If the fan insert is excessively soiled, the mechanism of the shutter and shut-off device can be checked for soiling and cleaned if necessary.

A manual triggering test of the shut-off device against fire transmission by removing the soldered strut is not permitted!