Periphery components for ESSER FACP
62 TI 798960.GB0 / 04.20
10 Development of audible alarm devices
Calculating the maximum number of alarm devices
The max. number alarm devices on the loop depends on the alarm device type and the length of the loop. The
individual load factors of the bus devices must be determined and added onto this. The max. permissible total
load factor of a loop is 96.
• The load factors, FACP battery capacity, etc. can be determined using the configuration tool at
www.esser-systems.com.
• The "Maxpector VAD Selection Guide" is available at www.esser.maxpector.com for online
planning and configuration of the devices.
Definition of sound pressure level
The sound pressure is the change in pressure which is generated by vibrating air molecules and subjectively
perceived as volume. The human ear can hear within an effective sound pressure range of 0 to 120 dB at a
frequency of 1000 Hz. This corresponds to a change in sound pressure of 20 N/m
2
(= Pa) or a factor of
1: 1,000,000 for the sound pressure level.
For the sake of simplification and to make the mathematical calculation easier, the logarithmic ratio of decibel (dB)
was introduced to describe the sound pressure level. The table below shows the expected sound pressure
levels in certain environments.
Environment Sound pressure level (dB)
*9
Residential area, at night < 30
Individual offices 50
Open-plan offices 55-60
Warehouses with electric fork-lift trucks 65-70
Warehouses with diesel fork-lift trucks 70-75
Production halls with machines or very loud traffic noise > 80
Jack hammer from a distance of 10 m 100
Siren from a distance of 10 m 110
Blows of a hammer in a blacksmiths shop from a distance of 1 m 130-150
*9
Example levels – the actual sound pressure levels may differ considerably from these values.
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