Siemens FDA2 Series Planning, Mounting page 32

4
Planning
Pipe system
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Symmetrical layout
Advantages of a symmetrical layout:
● Same number of aspirating holes on each pipework branch
● Pipework branches are the same length (tolerance ±10 %)
● Same gap between adjacent aspirating holes (tolerance ±10 %)
Asymmetrical layout
The structural conditions may necessitate an asymmetrical layout.
Conditions:
● Ratio of the number of aspirating holes in the shortest pipework branch to the
longest pipework branch is at least 1:2
● If possible, have the same gap between adjacent aspirating holes (tolerance
±20 %)
Long feed lines
If long feed lines are required between an aspirating smoke detector and the pipe
system, the maximum permissible pipe length must not be exceeded.
Topology and length of the pipework branches
Short pipework branches have a short response time and should therefore be
given precedence: U topology or double U topology.
Comply with the maximum permitted number of pipework branches and the total
length of the pipe system.
You will find further information in the chapter 'Limits to planning [➙ 34]'.
Maximum lengths of the pipework branches [m]
FDA221: 30
FDA241: 60
FDA261: 2 × 150
FDA262: 2 × 250
FDA221: 2 × 25
FDA241: 2 × 60
FDA261: 800
FDA262: 1200
FDA241: 120
FDA261: 800
FDA262: 1200
FDA261: 800
FDA262: 1200
Changing direction in the pipe system
Every change in the direction of the airflow causes losses and delays, and
increases the total flow resistance. You should therefore use as few branches and
bends as possible.
Comply with the permissible pipework lengths.
Example of changes in direction for the same pipe length:
A6V11783979_en--_a