Fire detectors
In essence, the detector is an element of Fire Detection Systems, receiving and processing information about the parameter controlled by it (smoke, heat, light emission). Acceptance of input data for a parameter is by sensing element (sensor), which in turn converts the values of the parameter into an electrical signal. The resulting signal is amplified and adjusted by an amplifier located in the detector and is fed to the threshold element.
An important highlight of the detector is its sensitivity. It shows what is the minimum value of controlled parameter, which will cause activation of the detector.
Another important highlight of the detector is the area (m ²) guarded by it. This is the area which the detector protects at a height of installation, and in case of fire in a section of that area detector should detect it for a predetermined period of time.
Types of detectors
There are different criteria, which makes classification of the detectors, the most important among which are:
According to the controlled parameter:
smoke detectors;
temperature (thermal);
flame;
multi-sensor (combined).
According to the configuration:
point
multi-point
linear
The most widely used are point detectors that control a parameter, close to a point (sensor). Multi-point detectors monitor parameters in close nearnessy to some or many fixed points (aspiration systems). Linear detectors detect fires along a continuous line (ray detectors, thermo-sensitive cable).
Point detectors - link point
Linear detectors - link linear
Aspiration detectors - link aspiration
For specific application:
For use on vessels
For use in potentially explosive atmospheres
According to the recipe of measuring the controlled parameter
maximum and differential. The maximum detectors bedded in excess of the value of the parameter of a predetermined value (threshold bedding). Parameter can be smoke, temperature, etc.. Differential (rate of rise) detectors, reply to the rate of turn of the controlled parameter, ie if within a specified period of time the temperature changes more speedily than has previously been determined. temperature differential (ie Termo-differential) detectors have a thorough set threshold level of bedding. The last concentrate two ideas in measuring the parameter controlled by one sensor.
According to dispatches to the type of alert control panel
two states detectors, detectors with some states and analog detectors. The first type are typical for conventional systems, and the third - for addressable fire detection system. Detectors with some conditions can be conventional as well as addressable. In the analog type, electrical signal is most ordinarily converted and sent in digital form.
According to the possibility of returning to normal
renewable and non-renewable. Most often renewable detectors are brought back to their former condition by the control panel by interrupting or reverse power polarity. Example for non-renewable detector is the thermo cable with fusible elements.
With today technology development, sensory parts of the detectors and the possibility of signal processing are greatly improved. As a result, device sensitivity to controlled parameter has been increased, while they become more defiant to the effects of confounding factors.
Combining of different types of detectors within the fire detection ideas or the use of multisensor detectors allows to control more than typical for fire events and is one of the most important factors for the effectiveness of Fds.
Fire Detectors
