Alarm device

The word alarm comes from the French A l'arme and is called to the weapon ( the only different in number Italian words Any poor or All'arme is also proposed as origin). This means figuratively, that a specific target group ( for example, the police or fire departments, but also the entire population ) to which the alarm is directed attention to an event and then to respond to it. The reactions and sequence of certain acts can occur while an alarm chain.

Such as fire alarms

If it came in a building to a fire outbreak, fire alarms could make acoustic signals. Now, the corresponding reactions of the building staff would be made, so leaving the building on appropriate escape routes. At the same time fire and rescue service could be alerted by a fire alarm system.

Triggering an alarm - Alarm

An alarm can be triggered automatically either by personal observation of a harmful event or. A common feature of all alarms is that the news of a harmful event or a hazard that is passed from a person of too few people, or people who are not experienced in dealing with the loss event, to a competent body. This is also referred to as Erstalarmierung. Furthermore, under the alert to understand the secondary alarm, when the alarm of this site to other relevant bodies or persons is distributed.

If you want to reach entire populations, using still the siren in connection with broadcast messages. For individuals the telephone or a radio service is primarily used. In groups, such as in task forces to Pager have prevailed, but also the SMS alarm is sometimes used.

Device alarm

Also with the help of measuring devices, an alarm can be triggered when a warning threshold is reached or exceeded. In Alarmdosimetern in radiation protection or Explosimetern in pollutant accidents, for example, an alarm tone sounds when the people would an area that would pose too high a burden for them to enter. During leak detection on gas lines, the gas detector is a beep or it flashes an indicator light when a gas leak is present.

A simple alarm devices also provide important when the inner function does not operate properly. If the battery level becomes too low to operate the equipment, it is often acoustically or visually.

Emergency plans

Adapted to the individual events ( depending on the alarm level ) precise alarm plans are created that describe exactly how to reactions occur ( expiration calendar, alarm and response regulations ). Here, a location adapted forces call is made (determination of means and personnel) in organizations.

Requirements for an alerting system

Just a alarm system needs to operate reliably. Therefore, certain minimum requirements for such a system shall be provided at the planning stage.

• The transmission of the alarm must be done very quickly and without delay.
• An alarm must be able to reach the group in question and identifiable for this.
• The system must be on call around the clock throughout the year.
• The alarm system must (if possible to underground car parks into ) ensure the availability of support staff through coverage and building penetration of the radio signal.
• The false alarm rate must be low, otherwise there will be a desensitization and incurring unnecessary costs.
• The trip must, if it is not done automatically, be easy to handle and have to use.
• Of an acknowledgment must be the delivery of the alarm can ensure.
• Should be notified to escalations at bouncing more participants.
• Especially for alerting via radio may not overlays done by other networks that can disrupt the network, or false alarms can trigger.
• Not to be underestimated is now also the cost factor and ease of maintenance.

Alarms in process control

Alarms have a control station ( for chemical plants, power plants, power distribution systems, etc. ) is of particular importance. The operator is "officially" over offset to inform you that a limit has been exceeded. No operator can claim that he had received no information about a threatening condition.

A horn sounds and an indicator light starts to flash. The operator should this alarm " quit". Only after the horn is turned off. The indicator light will stop flashing and changes to steady light. If the process variable that triggered the alarm, again within the limits, then turns off the indicator light.

When planning a control station necessary to consider which alarms are useful and necessary. If too many alarms scheduled, then the frequent horn creates stress for the operators. Therefore, it is also a distinction between initial and subsequent alarm. Subsequent alarms do not trigger horn and must not be acknowledged.

Many ( poorly planned ) consoles too high an alarm rate ( in some cases more than 2000 alarms per day and operator ), whereby the alarm system devalued and, in extreme cases, completely useless. A good alarm philosophy can be achieved through systematic alarm management. At least must plant components that are switched off, generate an alarm.

Historical

Alarms there, since people live in groups; as there was in the Middle Ages, the watchman who raised the alarm and the fire bell rang. Before the attack of enemy troops so-called Kreidfeuer were lit in Central Europe for larger areas.