Hard-wired smoke detectors are connected to a building's fire alarm control panel. Their primary source of power comes from a dedicated 120VAC circuit with a built-in charger to keep on-board batteries fully charged. They are therefore much more stable and reliable than battery-operated smoke detectors that are not connected to the building's fire alarm control panel. As an added safety precaution, hard-wired smoke detectors continue normal operation even when loss of power is present. The main fire alarm control panel switches to battery power in the event it senses a loss of AC or a brown-out condition.
Two types of hard-wired smoke detectors exist: optical, more commonly called photoelectric, detectors and ionization detectors. Optical/photoelectric detectors, as the name suggests, work by "seeing" smoke through a light source and photoelectric sensor. If there is no smoke, light passes in front of the detector but does not fall on it. When smoke appears and cuts into the light source, the light scatters and the sensor detects the interruption and sets off an alarm. Smoldering fire, the most common occurrence, produces heavy smoke that is quickly sensed by optical detectors.
With an ionization smoke detector, the detection of smoke particles is achieved by sensing a reaction between smoke and a small amount of radioactive material. In the simplest terms, smoke that enters the smoke detector reduces the ionization process by absorbing alpha particles. The flow of the current is interrupted and the alarm senses this. Ionization detectors sense fast-flaming fire much faster than optical detectors, since fast-flaming fires produce ion particles.
At Global Fire Control, we understand the importance of having hard-wired smoke detectors and are pleased to offer these products to our customers. More than that, we work directly with system's distributors to design the best possible solution for your particular needs. Please contact us at email@example.com for more information.
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