When incidents or emergencies occur at an industrial or transport facility, it is vital to inform the personnel about the danger as soon as possible. Up-to-date alerting systems allow transmitting an appropriate message throughout the whole facility area. An emergency message can be transmitted either automatically (as a prerecorded message, for example, “Attention! Fire alarm! Evacuate the building immediately!”) or semi-automatically (dispatcher’s address).
Industrial alerting systems are designed with account for the area and number of industrial premises, architectural peculiarities of the building and acoustic properties of materials. When equipment is designed, an acoustic report is made where the sound pressure and noise levels characteristic of a particular space are specified and additional interference sources are identified. Only after that parameters of loud-speakers are chosen and their layout is decided upon.
In case of an emergency, alerting systems transmit emergency messages, control evacuation and prevent panic. Division into zones is an important solution for industrial and transport facilities because in case of an emergency the responsible personnel must be notified first for execution of relevant instructions.
Local Alerting Systems
Local alerting systems (LAS) are systems operating automatically and designed for alerting in small areas. A message can be transmitted to one or several premises.
A wide range of functions implemented by alerting systems allows specialists to design a specific LAS for each particular facility.
LAS comprise loud-speakers for transmitting speech or voice messages, sirens for alerting, equipment, light indicators and lighting devices.
Alerting Systems and Interfacing with Civil Defense and Emergency Networks
Alerting systems and systems of interfacing with civil defense and emergency networks are designed for organization of large information areas and connection with civil defense and emergency networks. Electronic sirens are the main alerting instruments in these systems. Sirens can be used as stand-alone devices or as a part of the alerting system (up to 1000 sirens in a system). Electronic sirens are distinguished by high power, reliability and various control options.
Strict demands are made for siren self-diagnostics functions and the related infrastructure. In large alerting systems two independent channels are almost always used to control the siren network. It is desirable to use at least one radio channel with its own backup infrastructure (normally for 72 hours).