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Aspirating Smoke Detector
complete pipe project planning. The result for the maximum length of the complete air
sampling hose of type FAS-ASD-PHF16, which can be integrated within the pipe project
planning, after formula adjustment is:
Length of the air sampling hose = (Total pipe length – Air sampling pipe length) / 1.1
Length of the air sampling hose = (50 – 45 m) / 0.9 = 5,55 m
Notice!
The complete air sampling pipe must not consist of a single air sampling hose. Aspiration
reduction must not put about the air sampling hose.
4.14
Planning with air return
In some cases, in which differences of air pressure between the area of air sampling device
and the area of air sampling point exist, a channel of air pressure of the aspirated test air in
the pressure area of air sampling points can be necessary. Therefore, an air sampling hose
with a right length should be connected on the air outlet of the air sampling device.
As the transport time of an air sampling smoke detection device can be manipulated
negatively by an air return, the influence of the air return to the al-lowed total length of pipe is
to be respected.
An air return with a pipe with Ø 40 mm has no influence and can be projected and/or
retrofitted without reducing the total pipe length and / or retrofitted.
Consideration of air returns:
For calculation the maximum length of air sampling pipe, the length of the air return must be
multiplied by the certain factor a) and deducted from the allowed total length of pipe.
Air sampling pipe length = Total pipe length – (Length of the air return * Factor a)
Factors to calculate the lengths of air return (∅ 25 mm):
Length of the air return
0 – 5 m
> 5 – 10 m
> 10 – 25 m
Factors to calculate the lengths of air return (∅ 32 mm):
Length of the air return
0 – 5 m
> 5 – 10 m
> 10 – 25 m
Example: An air return (∅ 25 mm) from 10 m to be connected to a FAS/FCS. The allowed total
length of pipe is 50 m. The result for the maximum air sampling pipe is:
Air sampling pipe length = 50 m – (10 m * 1.6) = 48.4 m)
Bosch Sicherheitssysteme GmbH
Factor a
0.0
1.6
3.2
Factor a
0.0
0.0
1.0
Operation Guide
Planning | en
75
2018.04 | 2.0 | F.01U.130.926
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