Design
6
33
Bosch Security Systems
Seismic Detectors Application Guide
I-200153-1
04.2016
Room length (
l
) = 12m
Room length less 4m (sum of
d1
&
d2
) = 8m
sd
calculated at 3.75m, equally space the detectors at 2.67m (*note 1) apart for an even distribu-
tion of detectors and their coverage.
Note 1
Determine the number of detectors required after locating the first and last detectors. Subtract the
sum of
d1
&
d2
from the length and then divide the remaining distance between by number of de-
tectors plus1. For the previous example, 12 – 4 = 8, 2 detectors required; revised
sd
is 8 divided by
3 (2 de1), which provides an
sd
of 2.6m.
Table 6-1, Table 6-2, Table 6-3, and the associated graphics show how to determine the correct
number of ISN-SM-90 detectors to provide comprehensive detection coverage on a concrete wall
16m in length and with a height of 3m. The variable for each scenario is the detection radius setting
of the detector.
6.1.1
Calculating the number of detectors required - Example 1
This installation utilizes ISN-SM-90 detectors on a concrete wall.
Radius
(m)
Distances
Calculated
Length
(m)
Recommended
Distances
Recommended
Length (m)
Recommended num-
ber of Detectors
5
d1
4
d1
3
5
sd
7.5
sd
5
sd
5
5
Detector
radius (
r
)
5
d2
3
3
Table 6-1: Wall design - 5m detection radius
For the example detailed in Table 6-1 using two detectors at the calculated locations provides the
minimum detection that is sufficient to provide coverage for the wall. For maximum performance
and efficient coverage Bosch Security Systems recommend a more balanced layout using 3 detec-
tors.
In Figure 6-4 the sum of the calculated distances
d1
,
sd,
and the detector radius
r
slightly exceeds
the length of the room using two detectors.
Figure 6-4: Wall design example 1 - calculated distances
Figure 6-4 shows a representation of the protected wall with the calculated detector spacing.
Figure 6-5 shows a more balanced detection layout using three detectors.
