34
en | Planning
FAS-420-TM Aspirating Smoke Detector
F.01U.088.878 | 4.1 | 2010.11
Operation Guide
Bosch Sicherheitssysteme GmbH
3.2
Principles of Pipe Planning
The aspiration pipe network must be designed such that all possible fires in the monitoring
area can be dealt with at an early stage.
The number of air sampling openings and the structure of the pipe system depend on the size
and geometry of the monitoring range. The pipe system must be laid out according to the
planning guidelines in this chapter, taking into account the following issues:
Symmetrical structure
The pipe system should preferably have a symmetrical structure, i.e.
–
Same number of air sampling openings per pipe branch
–
Same pipe branch lengths (should not exceed ± 20% deviation)
–
Same distance between neighboring air sampling openings on the smoke aspiration pipe
(should not exceed ± 20% deviation).
Asymmetrical structure
If structural circumstances dictate that the pipe system is to be designed asymmetrically (see
Figure 3.1
), the following conditions apply:
–
The number of air sampling openings and the length of the shortest and longest pipe
branch within the pipe system must not exceed a quantity ratio of 1:2.
–
The distance between neighboring air sampling openings on the smoke aspiration pipe
must be equal (should not exceed ± 20% deviation).
–
The diameters of the air sampling openings are determined separately for each pipe
branch. The diameters depend on the total number of air sampling openings in the pipe
branch in question.
Figure 3.1
shows a typical U-pipe system with three or six air sampling openings and the air
sampling opening diameters calculated according to
Section 3.6 Standard Pipe Planning
.
Pipe diameter
As a rule, the pipe system is created using pipes with an external diameter of 25 mm. PVC or
halogen-free pipes can be used. Halogen-free pipes are to be used in preference for
equipment monitoring.
Branch length
To achieve short transport times for the smoke aerosols in the aspiration pipe and thus quick
detection, it is better to plan several short branches than fewer long ones (preferably U and
double U-pipe system).
Pipe configurations
Depending on the area geometry, five pipe configurations can be selected (see
Figure 3.2
):
–
I
-pipe: pipe system without branches.
Figure 3.1
Example of a symmetrical and an asymmetrical U-pipe sys-
tem
A
Symmetrical pipe system
B
Asymmetrical pipe
system
A
B
FAS / FCS
2,5
3,4
3,6
3,8
3,0
2,5
2,5
3,2
3,0
2,5
3,0
2,5
2,5
3,2
3,0
2,5
3,0
2,5
2,5
3,2
3,0
Summary of Contents for FAS-420-TM
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