Bosch FAS-420-TM - Page 54

54 en | Planning FAS-420-TM Aspirating Smoke Detector
F.01U.088.878 | 4.1 | 2010.11 Operation Guide Bosch Sicherheitssysteme GmbH
The open end of the air-return pipe is sloped at an angle of 45° (see Figure 5.5, Page 71).
The distance of the air sampling openings to one another and to the duct wall is represented
in the following table.
Diameter of the air sampling openings
The diameter of the air sampling openings is derived from the number of air sampling
openings. The precise value can be obtained from Section 3.8 Simplified pipe planning.
The pipe is closed with an end cap without bore hole.
Arrangement
The air sampling openings must face the airflow.
Note when planning that the air-conditioning ducts are often only accessible from two sides
for installation of the pipe system.
Example
Figure 3.19 shows two planning examples of pipe systems in air-conditioning ducts.
Figure 3.18 Air-return pipe
F Front view
APlan view
1 Air-conditioning duct
2 Duct adapter
3Airflow
4Aspiration
5 Air-return pipe
b Width of air-conditioning
duct
v
1
-v
4
Flow speed
1
1
5
2
2
i
1 2 3 4 5 6 7 8 9 10
4
3
3
F
v
1
v
2
v
3
v
4
A
FAS / FCS
FAS / FCS
5
1/2 b
b
2
F
A
S
-
4
2
0
-
T
M
s
e
r
ie
s
A
B
Bore distances Duct cross-section
≤ 0.5 m²
Duct cross-section
≤ 0.5 m²
Distance of the air sampling openings to the
wall
100 to 200 mm 200 to 300 mm
Distance of the air sampling openings to one
another
100 mm 150 mm