D-FL 200 / Rev. 6
9
______________________________________________________________________________________________________
Industrie Elektronik GmbH & Co KG
(Fig. 9) D-FL 200 flange
The required minimum length of the welding flanges can be obtained from the next equation:
L
(20
D
150 cos )
sin
W
=
+
+
⋅
α
α
Equation 9
with:
L
Length of the flanges [mm]
D
W
Wall thickness of the duct [mm]
3.3. Purge Air System
The use of a purge air system helps to prevent the surfaces from getting dirty prematurely and also
protect the system against the heat of the flue gas. If a purge air system is not used, the monitoring
system may suffer from excessive dirt accumulation in applications where negative pressure is
prevalent. This is especially true if the boiler is shut down, absence of an upward draft and during start-
up phase.
The following points should be considered when selecting a location to mount the purge air system:
•
The intake air must be as dry and dust-free as possible.
•
The temperature of the intake air may be a maximum of 313 K (104
°
F/40
°
C).
•
When mounting the system, the filter has to be vertical. The dust valve must situated at the
bottom.
•
Adequate space must be left for exchanging the filter (see page 11).
If the purge air system is being mounted outdoors, the
weather hood
D-WSH 290 GN
is available.
