Not everyone pays attention to small appliances that hide on the ceilings of rooms. This is natural, because, seeing something everywhere and everywhere, the brain simply ceases to perceive this something as an unusual phenomenon. And besides, one must also take into account the fact that any such devices are made with the expectation of maximum mimicry with the surface on which they are fixed. Such a complex explanation was required by an ordinary fire alarm, the importance of which should not be underestimated.
Fire Detector Design
Even if you paid attention to various sensors, it still does not mean anything. The fact is that such catchers are just a control system, so to speak, external senses serving the whole system.
They can respond to a wide variety of stimuli, and therefore, if we discuss the types of fire alarms, one cannot touch upon such a topic.
The detector, which is the very warning system that is proudly called the alarm system, consists of many parts, where the sensors are only the external part of the structure. So, for example, in addition to traps that respond to various fire factors (smoke, temperature, open fire, etc.), this can be a whole signal recognition system, communication centers with other components, as well as an automatic fire extinguishing mechanism, etc. d.
Types of fire alarms and communications
The classification of such devices is quite wide. This is mainly due to the fact that they are used everywhere. It is reasonable that different types are used for each class of premises.
However, it is quite difficult to list the main types of fire communications and alarms, simply because they classify these mechanisms in very different ways. The device is quite complex, and there are also a lot of technical solutions, so we will go through the main types.
Type of transmitted signal
Actually, the system of signal transmission from signaling to other elements is a mandatory part of the design, regardless of type. Indeed, if the sensor detects a fire, but the signal is not received, there is no sense in such a device at all. But the mechanism of action can be of four main types:
- Single-mode, which signals only a fire as such. That is, the sensors are turned on only if the necessary conditions arise. But these types of fire alarms are no longer used.
- The most common are dual-mode. The point here is that when the catchers do not fix a dangerous situation, they transmit a signal that everything is in order. This means that the system is functioning normally. If the signal does not pass, then the sensor is broken, and it must be replaced.
- Multi-mode models are “sharpened” specifically for large buildings. After all, the inspector will not walk along kilometer-long corridors just to check why the trap does not transmit. Such a system is the main type of fire alarm in the school. Security requirements are high there, and they can only be ensured in this way.
- Analogs are the most advanced. They respond not to critical, but to any change in tracked indicators.
Signal transmission
This characteristic can also distinguish types of fire alarms from each other. Transmission may be:
- wired using cables;
- wireless, where they use a radio signal, or even just a Wi-Fi network.
Further, there is also a classification for signal transmission, but here it is more about the parameters of the information itself:
- Models with a threshold definition start transmission only at the moment when the temperature, smoke, or some other characteristic passes the allowable threshold;
- Differential detectors focus on every change in parameters. So you will be notified when any increase or decrease in value;
- Combined systems work by detecting critical changes, but tracking all the others at the same time.
Number of sensors - localization rules
The salt is that for rooms of different sizes, the types of fire alarms will be different.
According to this parameter, all fire detectors will be classified as follows:
- Point models are one sensor that most often attaches directly to the detector to save space and ease of use. Just such functionality you can see in almost every apartment.
- Multipoint models are many sensors that hide in one particular place. That is, if point devices respond to any one specific parameter, then these devices can immediately track a whole galaxy of them.
- Linear ones, in turn, are interesting in that they track a number of devices. That is, an arbitrary line is drawn from the detector along which, for example, emitters and photocells are installed. The latter allows you to track the level of smoke in the room. Such systems, as in the above example, are called paired, but they can be single.
Type of sensors
The classification of catchers is just that factor by which the working area of the alarm is determined. Despite the importance of the previous paragraphs, the choice is most often made precisely on the basis of the quality of the sensors. There is no escape from this.
For example, the type and type of fire alarm in a school can be very different. But here what catchers will be installed, defines the law on fire safety of institutions.
Heat traps
This is the oldest type, since they were used one hundred fifty to two hundred years ago. Today, their design is an ordinary thermocouple, which, in turn, starts to work, that is, conduct current, only at a certain air temperature. These types of fire alarms, photos of which are available in an article submitted to readers, can be seen in any building of the last century.
The problem here is pretty obvious - air temperature rises only when the fire has flared up.
That is, there is something wrong with the speed of response. The last century was the heyday of such sensors, they were installed everywhere. At the same time, other species are gradually replacing them.
Smoke exhauster
If we talk about such specific things as the types of automatic fire alarms, then not to recall smoke detectors would be sacrilege. After all, it is they who today occupy a leading position in this market, which is special in every sense.
Smoke is one of the main signs of a fire. Interestingly, he appears first in most cases. Often it is even possible to observe smoke for quite some time until a flame appears - for example, during smoldering wiring. So, the advantages over the previous type are obvious. The fire is monitored at the embryonic stage, and therefore it allows you to take preventive measures.
Everything works on air transparency, but smoke can be determined according to different principles. Linear models use a directed beam of different ranges in their work - a reflective or photocell is also required for operation, which will respond to a beam.
When there is no reaction, then transparency is broken, the sensor will work.
If the first type uses the optical and ultraviolet wavelength range, then in the second, spot, the work is based on infrared radiation.
Such waves simply should not return to the trap under normal conditions. If the signal is reflected back, it means the presence of foreign substances in the air.
Point sensors cost less than linear ones, but the latter, respectively, are more reliable. So you still have to choose.
Flame sensors
This type is common for industrial premises, workshops, etc. That is, it is possible to work only with flame, since the air is dusty, and the temperature is a priori elevated.
Flame sensors can be infrared or ultraviolet - these are two main types.
Thus, the device reacts to the generated heat, but immediately, and not when it heats the air, as it works with thermal traps. You can also use electromagnetic sensors - they will respond precisely to this component of the flame, thus avoiding false alarms.
Signaling
The fire can also be monitored by the usual ultrasonic security system of the apartment.
The bottom line here is on what principle the device works. In this case, this is the movement of air masses.
The alarm will respond not only to the intruder, which moves the air when moving, but also to an open flame. The latter will certainly raise a whole layer of heated air up, which will trigger the device.
However, you should not rely on such a system, since it is not designed to track fires.