7
Vent the valve via the two needle valves. Then close the two
needle valves again.
Close the two shut-off valves.
Open needle valve 1 and slowly release the pressure via need-
le valve 1 (a few drops).
Close the needle valve again. Observe the tundish. The diffe-
rential pressure must be above 140mbar and the inlet back-
flow preventer (RV1) must close completely again, otherwise
there is contamination or a mechanical defect.
Open the needle valve 1 further and relieve the medium pres-
sure zone until it is completely drained.
Maintenance - inspection of
check valve 2
To test the outlet check valve (RV 2), the intermediate pressu-
re zone must first be completely drained.
Open the outlet shut-off valve.
If water drips from the tundish, there is a mechanical defect
or contamination of the outlet check valve.
In this case the backflow preventer cartridge must be cleaned
or replaced.
Close both maintenance ball valves, remove the measuring
device and reinstall the pressure gauge plugs.
Open the two shut-off valves.
