Kessel Staufix FKA Instructions De Pose Et D'utilisation page 36

6.3.3 Leak test
Move the mechanical emergency closure lever to the
CLOSED position.
Close the motor-driven flap by pressing the "flap" button.
Screw the drain plug out.
Screw the testing funnel in place.
Pour water into the funnel up to the test pressure height of
10 cm and observe the water level for 10 minutes. If nec-
essary, keep the water level to the original level by refill-
ing.
The backwater valve is considered watertight if no
more than 0.5 litres of water has to be refilled during
this time.
Note the result in the log book or maintenance log.
Screw the testing funnel out, screw the drain plug in.
Move the emergency closure lever to the OPEN position.
Check whether the drain plug is sealed tight (no gap).
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Open the motor-driven flap by pressing the "flap" button.
Installation and operating instructions 010-842_01