Bosch FAS-420-TP2 - Planning with Acceleration Openings and Forced Airflow

Aspiration smoke detector LSN improved Planning | en 57
Bosch Sicherheitssysteme GmbH Operation guide 2020.04 | 6.1 | F.01U.029.275
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Example of a pipe system with long pipe feed lines for area monitoring
The general pipe planning is restricted by the use of long pipe feed lines as follows:
– Pipes with a40mm diameter increase transport time.
– 1m pipe with a40mm diameter replaces 3m pipe with a25mm diameter.
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∅ 40 mm: ≤ 100 m
∅ 25 mm:
≤ 20 m
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FAS / FCS
Example of special planning for high-rise warehouse
A basic pipe can be installed for high-rise warehouse planning, from which the stub-shaped
aspiration pipes are routed.
4.10 Planning with acceleration openings
Acceleration openings
In order to meet individual regulations, it may be necessary to decrease the transport time of
the systems. This can be fulfilled by fitting the ends of the pipe branches with acceleration
openings, which increase transport speed. Depending on the regulations concerning transport
time, it may be necessary to dimension an acceleration opening with the same or double the
diameter of the last air sampling opening on a pipe branch. Only authorized aids should be
used to calculate the transport time. The additional airflow of the acceleration openings also
reduces the sensitivity of the air sampling openings. If required, this reduction can be offset as
follows:
Method of resolution Primarily used in
1 Increasing the sensitivity of the detector
module
Previously installed systems
2 Reducing the number of air sampling
openings
Systems currently being planned
1. Option: increasing the sensitivity
Reduced sensitivity at the air sampling openings can be offset by using a more sensitive
detection setting. A distinction must be made regarding whether the cross-section of an
acceleration opening is smaller or the same as:
– the cross-section of the last air sampling opening of a branch
– the doubled cross-section of the last air sampling opening of a branch