Installation of the ducting
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67
Calculating the total ducting
length
The entire ducting system (including
bends and components) generates air
resistance that pushes against the
exhaust air. The relative pipe lengths
and total ducting length have to be
calculated for this reason:
– The
relative pipe length
(table I)
indicates how much greater the air
resistance of a bend is, for example,
compared to 1 metre of a straight
plastic waste water pipe.
– Adding all of these relative pipe
lengths together gives the
total
ducting length
. This is not the actual
length but a calculated figure. The
total ducting length (table II)
represents the air resistance of the
entire exhaust air system.
Because a larger
pipe diameter
(ta-
ble) reduces the air resistance, a longer
total ducting length requires a greater
pipe diameter.
Procedure
Measure the length needed for the
straight sections of ducting. Multiply
the length by the corresponding
relative pipe length from
table I
.
Calculate the number of bends and
elbows needed. Use
table I
to help
you add together their relative pipe
lengths.
Calculate the total length of the
ducting: Add up all of the relative
pipe lengths calculated under
and
.
Refer to
table II
for the pipe diameter
needed for the total ducting length.
Table I
Components
Relative
pipe
length
Exhaust air hose
(highly flexible)
1 m, installed straight
45° bend (radius of bend = 0.25 m)
90° bend (radius of bend = 0.25 m)
1.8 m
1.5 m
2.5 m
Exhaust air hose (flexible or
flexible aluminium) /
plastic waste water pipe
1 m, installed straight/straight pipe
45° bend (radius of bend = 0.25 m)
90° bend (radius of bend = 0.25 m)
1.0 m
0.6 m
0.8 m
Wall pipe or window connection
with inserted grate
with non-return flap (swinging flap)
3.8 m
1.5 m
Non-return flap for integration
into the ducting
(see “Shared exhaust air duct”)
14.3 m
Flat ducting (for stacked
installation)
11.0 m
Table II
Total ducting
length
Pipe diameter
maximum 20 m
maximum 40 m
maximum 80 m
100 mm
125 mm
150 mm
Содержание PDR 908 EL
Страница 96: ...M Nr 11 226 810 02 en AU NZ PDR 908 EL ...
