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60
en | Planning
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:
–
–
Air sampling openings
Pipe
1
2
3
shape
I
0.5
0.6
0.7
0
6
5
U
0.5
0
M
0.5
0
2 x U
4 x U
Table 4.2: Factors for increasing the sensitivity (acceleration opening corresponds to one air sampling opening)
Air sampling openings
Pipe
1
2
3
shape
I
0.3
0.5
0.6
3
0
0
U
0.3
3
M
0.3
3
2 x U
4 x U
Table 4.3: Factors for increasing the sensitivity (acceleration opening corresponds to two air sampling openings)
Example:
A class B double U-pipe system with 24 air sampling openings is planned. According to EN
54‑20 or ISO 7240-20 , 24 openings are permitted in class B at a sensitivity of 0.25% LT/m. In
order to increase the transport time, an acceleration opening the same size as the last air
sampling opening is to be used.According to 1. Option: increasing the sensitivity, page 60, the
necessary sensitivity of the detector module in this case is 0.25 % LT/m * 0.85 = 0.1875 % LT/
m.
2018.04 | 2.0 | F.01U.130.926
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
4
5
6
7
8
0.8
0.8
0.8
0.8
0.8
0
3
5
7
8
0.6
0.7
0.8
6
5
0
0.6
6
0.5
0.6
0
6
0.5
0
4
5
6
7
8
0.6
0.7
0.7
0.7
0.8
6
1
5
7
0
0.5
0.6
0.6
0
0
6
0.5
0
0.3
0.5
3
0
0.3
3
9
10
11
12
13
0.9
0.9
0.9
0.9
0.9
0
0
1
2
2
0.8
0.8
3
5
0.7
0.8
5
0
0.7
5
9
10
11
12
13
0.8
0.8
0.8
0.8
0.8
1
3
4
5
6
0.7
0.7
1
5
0.6
0.6
0
6
0.6
0
Operation Guide
Aspirating Smoke Detector
14
15
16
18
20
0.8
0.8
0.9
0.9
7
8
0
0
0.8
0.8
3
5
0.8
0.8
0
3
0.6
6
14
15
16
18
20
0.7
0.8
0.8
0.8
7
0
1
3
0.7
0.7
1
5
0.6
0.7
6
1
0.5
0
Bosch Sicherheitssysteme GmbH
21
24
32
0.8
7
0.8
5
0.7
0.8
5
0
21
24
32
0.7
7
0.7
5
0.6
0.6
0
6
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