Bosch ISN-SM-30 - Calculating the Number of Detectors Required - Example 3

6
Design
36
Bosch Security Systems Seismic Detectors Application Guide I-200153-1
04.2016
6.1.3 Calculating the number of detectors required – Example 3
This installation utilizes ISN-SM-90 detectors on a concrete wall.
Radius
(m)
Distances
Calculated
Length (m)
Recommended
Distances
Recommended
Length (m)
Total
Detectors
2.5
d1
2
d1
2
2.5
sd
3.75
sd
3
2.5
sd
3.75
sd
3
2.5
sd
3.75
sd
3
2.5
d2
2
sd
3
d2
2
5
Table 6-3: Wall design - 2.5m detection radius
Figure 6-8 shows the calculated sd, d1 & d2 distances.
In this example, the calculation using the d1 and the sd does not provide full detection coverage
using four detectors and so a fifth detector is required to provide coverage.
F
igure 6-8: Example 3 - inadequate coverage
Figure 6-9: Example 3 - detector spacing with balanced coverage shows the recommended detec-
tor spacing. This example uses 5 detectors, keeping the d1 & d2 as per the calculated distance but
decreasing the sd to provide balanced coverage.
To balance a system design, the distances d1, d2 & sd may be reduced but never in-
creased.
F
igure 6-9: Example 3 - detector spacing with balanced coverage