Not everyone pays attention to small appliances that hide on the ceilings of the premises. This is natural, because, seeing something everywhere and everywhere, the brain simply ceases to perceive this something as an unusual phenomenon. And besides, we 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.
Design of fire detector
Even if you paid attention to various sensors, it still doesn't mean anything. The fact is that such traps are just a control system, so to speak, external sense organs that serve the entire system.
They can react toa wide variety of irritants, and therefore, if we discuss the types of fire alarms, it is impossible not to touch on such a topic.
The detector, which is the same warning system that is proudly called an alarm, consists of many parts, where the sensors are only the outer part of the structure. So, for example, in addition to traps that respond to various fire factors (smoke, temperature, open fire, etc.), it can also be a whole signal recognition system, communication nodes with other components, as well as an automatic extinguishing mechanism, etc. e.
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 makes sense that different types are used for each room class.
However, it is rather difficult to list the main types of fire communication and alarm systems, simply because these mechanisms are classified very differently. The device is quite complex, and there are also a lot of technical solutions, so let's go through the main types.
Type of transmitted signal
Actually, the signal transmission system from the alarm to other elements is a mandatory part of the design, regardless of type. Indeed, if the sensor detects a fire, but the signal does not arrive, there is no point in such a device at all. But the mechanism of action can be of four main types:
- Single-mode, which signals only about the fire as such. That is, the sensors turn on only if the necessary conditions occur. But these types of fire alarms are no longerapply.
- The most common are dual-mode. The point here is that when the traps do not detect 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 needs to be replaced.
- Multi-mode models "sharpened" specifically for large buildings. After all, the inspector will not walk along kilometer-long corridors just to check why the trap is not transmitting. Such a system is the main type of fire alarm in the school. Security requirements are high there, and this is the only way to ensure them.
- Analogue is the most advanced. They react not to critical, but to any change in monitored indicators.
Signal transmission
This characteristic can also distinguish types of fire alarms from each other. Transfer can be:
- wired using cables;
- wireless, where they use a radio signal, or even just a Wi-Fi network.
Next, there is also a classification according to signal transmission, but here it’s more about the parameters of the information itself:
- Threshold models only start transmission when temperature, smoke, or some other characteristic exceeds the threshold;
- Differential detectors emphasize every change in parameters. So you will be notified whenever the value goes up or down;
- Combined systems work by identifying breaking changes but trackingand everyone else at the same time.
Number of sensors - localization rules
The s alt 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 mounts directly to the detector for space saving and ease of use. Just such functionality you can see in almost every apartment.
- Multi-point models are many sensors that hide in one specific place. That is, if point devices respond to any one specific parameter, then these devices can track a whole galaxy of them at once.
- Linear ones, in turn, are interesting because they track a number of devices. That is, an arbitrary line is drawn from the detector, along which, for example, emitters and photocells are placed. The latter allows you to monitor the level of smoke in the room. Such systems, as in the example above, are called paired, but they can also be single.
Sensor type
The classification of traps is exactly the factor by which the working area of the alarm is determined. Despite the importance of the previous points, the choice is most often made 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 are the traps that will be installed,defines the law on fire safety of institutions.
Heat traps
This is the oldest type, since they were used one hundred and fifty to two hundred years ago. Today, their design is a conventional 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 the article submitted for the judgment of readers, can be seen in any building of the last century.
The problem here is pretty obvious - the air temperature only rises when the fire is lit.
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, they are gradually being replaced by other species.
Smoke extractors
If we talk about such specific things as types of automatic fire alarms, it would be blasphemy not to mention smoke detectors. After all, it is they who today occupy a leading position in this special market in every sense.
Smoke is one of the main signs of fire. Interestingly, he appears first in most cases. It is often even possible to observe smoke for quite a long time until a flame appears - for example, when wiring is smoldering. So, the advantages over the previous type are obvious. The fire is monitored at an embryonic stage, and therefore it allows you to take preventive measures.
Everything works on the transparency of the air, but smoke can be determined according to different principles. Linearmodels use a directional beam of different ranges in their work - a reflective or photocell is also required for operation, which will respond to the beam hit.
When there is no reaction, then the transparency is broken, the sensor will work.
If the first type uses the optical and ultraviolet wavelengths, then the second, point, 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 are, accordingly, more reliable. So you still have to choose.
Flame detectors
This view is common for industrial premises, workshops, etc. That is, you can only work with a flame, since the air is dusty, and the temperature is a priori increased.
Flame detectors can be either infrared or ultraviolet, the two main types.
Thus, the device reacts to the heat generated, 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 positives.
Alarm
Fire can also be tracked by conventional ultrasonicapartment security system.
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 an intruder who moves air while moving, but also to an open flame. The latter will surely raise a whole layer of heated air up, which will cause the device to work.
However, relying on such a system is not worth it, as it is not designed to track fires.
