4
in
in
ato
fl
unblocked manually. Before unblocking the valve flap, the complete valve should be checked after
an explosion has occurred for possible damage which could hinder the proper functioning.
Note that the inner flap can also lock itself due to reverse current cleaning of the filter. If this is
the case, the installation distance and reverse flow pressure should be checked to reduce the
effect on the non‐return valve.
Figure: 4 Locking system inside the Non‐Return Valve
Figure: 5 Illustration how the indicator works
When the dicator is
this position the flap
inside the non‐return
valve is open
When the indic r is in
this position the ap inside
the non‐return valve is
closed and has to be
unlocked manually
