Fire alarm system

Hi habrachelovek. Being in a cozy office or any other place of work you probably paid attention to all these incomprehensible things on the doors, walls, windows and the ceiling. So, these things help to preserve your property, values ​​and even life.

Today I will try to tell how these things are arranged, why they are needed and how it all works. Sometimes it is just not superfluous to know about the nature of the things that surround you. Under the cut a lot of useful bukaf , pictures and traffic.

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A few words about the alarm

The alarm is autonomous and console. Autonomous alarm system is not displayed anywhere, maintenance and control is carried out by the owner, an authorized person or working personnel of the protected object. Console protection is connected to the central monitoring station of the duty personnel of private security, fire service or non-state private security company (PSC), as a rule, through the PBX or radio channel.

Security alarms have 3 lines of protection in which sensors of their type are used.

• 1 frontier - the perimeter of the protected object (windows, doors, walls)
• 2 frontier - Interior of the object (apartments, offices, garages)
• 3 frontier - Objects indoors (safes, paintings and other valuables)

According to the type of application, fire alarm sensors are also divided into several groups, I will highlight 3 main ones that are found everywhere.

• Thermal
• Smoke
• Hand held

Reception and control devices

At the head of the alarm systems are receiving control devices (PCP), in which case they include sirens, voice alerts, and also “call” the police and firefighters. These devices monitor the state of their alarm loops (AL), which can be many. The sensors (detectors) of security or firemen are connected to the loops, which can also be more than a dozen. If triggered, the sensors can (depending on the type of sensor and the method of its connection) close or open the loop. Usually, at the end of the loop, an end element (OE) is connected, the role of which can be played by a diode, a capacitor, and in most cases, as a rule, a resistor of a certain value is protection from possible sensor failures and not competent burglars who try to close the loop. Increasingly in modern devices, the terminal element is informative in nature in order to report various faults in the loop.



It turns out that the control panel does not allow the loop to go beyond the set nominal of the end element, otherwise the control panel will “think” that the loop is not working and will turn on the corresponding indication or is violated and go into an alarm in parallel by manipulating its output.
The control panel outputs are also different, the main ones are the usual relay, the radio transmitter, the RS-485 interface, and various signal-starting devices. The output of the control panel may even become a loop of another control panel. One control panel can have several types of outputs simultaneously.
A characteristic feature of the device is also a way to control it.

So, the control panels differ in the number of loops, the OE ratings of these loops, the control method, the number and type of outputs.

Common Detectors

Announcers are designed to record certain events and report them to the control panel. To do this, they are equipped with an output relay, radio transmitter or RS-485 interface (addressable detectors). Detectors can also be autonomous, i.e. not to work with the control panel, but to have its own means for light and sound notification in the event of a response. Some can be combined and have properties of several types of detectors at the same time. Most detectors are protected against opening the case, many also require separate power supply.

QMS



The indicator is magnetic-contact. It consists of two parts - a reed switch and a magnet. Reed switch getting into the action of the magnetic field closes its contacts. Mainly used on doors and windows, has different designs for suitable operating conditions. Now you know where to get the magnets.

Security Acoustic Detectors



Consist of a microphone and transducer. Record the sound of breaking glass. To reduce false alarms from extraneous sounds - tuned to a certain range of sound frequencies. Many detectors allow you to adjust the sensitivity, are equipped with an indication of events and can store the trigger in memory.

The so-called "volume"



Under the "volume" is commonly meant - motion sensors. The most common infrared and radio wave.
The principle of operation of IR sensors is based on the registration of changes in the thermal background in the zone of the sensor per unit of time. Therefore, they are not recommended to be directed or installed in places with possible frequent temperature changes (radiators, air vents, windows).
The principle of human detection based on the registration of the Doppler frequency shift of the reflected microwave signal (UHF) signal that occurs when a person moves in an electromagnetic field created by a microwave module is implemented in a radio wave detector. Such sensors can be masked for obstructions from materials that transmit radio waves. ( Original and more detailed )
Some "volunteers" allow you to protect the premises with pets inside. Many detectors also allow you to adjust the sensitivity, are equipped with an indication of events and can store the trigger in memory.

Fire Smoke Detectors



Smoke opto-electronic fire detector. Designed to detect fires, accompanied by the appearance of smoke in enclosed spaces. The principle of operation of the detector is based on the registration of changes in the optical density of air per unit of time, with a threshold value characteristic of smoke. The operation of the detector is accompanied by the inclusion of a built-in optical indicator (LED).
Dust and small insects trapped inside can also cause a trigger, so at least twice a year such detectors require inspection and cleaning.
In the case of a false alarm, do not be lazy to pay attention to the LEDs of such sensors, remember the one for which it was on and indicate it to the service personnel. This will save you from future headaches.

Heat thermal detectors



Register the excess temperature in the room above the threshold. The old samples consisted of two electrodes fused with low-temperature solder. Modern samples are more reliable and have resistance thermometers or thermal relays. Each detector is configured for a specific response temperature. Some have LED displays and allow you to visually determine the triggering of a specific detector.

Manual Fire Detectors



In case of fire, they are actuated manually. Usually installed at the exits.
At first, as soon as they were commissioned in Russia, the detectors were impersonal buttons, and the inquisitive minds of compatriots, while others simply from hooligan promptings did not give the fire services rest day or night. A little later, in order to defeat the mentality, the detectors were equipped with detailed information on the use directly on the case, and some also equipped with a device for sealing.

Alarms

I almost forgot. Unlike security and fire alarms, alarming is more than fully designed to protect people from their own kind. The most widespread alarm buttons of various types and designs. Initially, the cash registers were equipped with buttons, the buttons were located under the tables, sometimes they were special pedals. Then they began to equip places of sale of alcoholic beverages, the guards appeared portable radio charms. Then school and preschool institutions - first of all, this was influenced by the events in Beslan. Now the buttons are used everywhere, shops, offices, state. institutions.
And thanks to the alarm, you can do interesting things .

Afterword

They were always touched by films where, with the help of unthinkable devices and high technologies, a group of brave guys hacked into the safes of federal banks and absolutely not noticeably escaped the guards with all the good :)
In truth, in reality, most likely such heroes will have a single attempt, unless of course the lack of support of the security company and the apathy of the service personnel help them. It happens that the employer himself chases for cheapness and eventually gets a raw project with cheap nameless alarm devices, with constant false alarms and a bunch of other headaches.