Fire Detection & Warning Systems
Air Sampling Smoke Detectors
In this system; the air pulled from the zones required to be protected is sent to the detector via a pipe network. The detector is of high sensitivity. The operation begins as a result of warning signal.
This system which is very advantageous in terms of installation cost; doesn’t present any problem with regard to routine maintenance. They’re used in places with entrance-maintenance problems, atrium, high-rise buildings, structure gaps, complex roof structures, high-protection necessitating spaces with installations should not to be seen, areas having environmental pollution such as dust and dirt. It has 2 types including primary sampling and secondary sampling.
Primary sampling system: In this system; a detector having a volume of 1500 cubic meters is used. It operates on the assumption that the smoke particles in the protected zone will pass through the ventilation system. They’re used in cases where the air speed is faster than 1 m/s. Its performance rises to optimum when used together with air-conditioning systems.
Secondary sampling system: The analysis process takes place with the sampling holes located in the pipe network. It is preferred in situations where air movements are slow. The diameters of the holes present in pipe network are determined with the help of a hydraulic calculation program. In the areas where the ceiling height is much such as high warehouses and atriums; the use of multi-level sample holes is deemed appropriate.
Sensitivity of Air Sampling Smoke Detectors
This system; avoids possible damages that may cause life or property loss by dint of its sensitivity. It allows the fire to be detected during early phases by demonstrating high sensitivity for the fire. It has 3 different sensitivity levels. The sensitivity of normal point smoke detectors ranks 1st among them.
Better efficiency is obtained above 2% with increased sensitivity and meanwhile for high sensitivity; it ensures getting better efficiency from 0.8%.
The sensitivity resulting from more than one point smoke detectors; can be provided by only one high-precision air sampling detector.
At the same time, they’re able to make arrangements also in areas where point detectors can’t be used. Its installation and maintenance including the piping system cost less in comparison with point detectors, and it is simpler as well. If an adjustment has been made according to 0.05% smoke density in a detector; average of 1% system sensitivity would be in a 20-hole system. The detectors most often used in air sampling system; are light-distributing detectors.
There are many causes for this. However, especially; not causing pollution and having a long life are among the most important factors. There is not any other detector exhibiting performance higher than light-distributing detectors particularly in dirty and dusty environments.
The air enters the relevant zone; is sent along with high-energy light resource. If there are smoke particles in the air; it causes scattering of light. The amount of distributed light is directly proportional to the amount of smoke. The solid state is analyzed by the light receiver and sophisticated filter or dust-preventer is used in this system for the purpose of avoiding dusts.