Detector or Alarm?
Smoke Detector ≠ Smoke Alarm
Would you call a phillips screwdriver a flathead screwdriver? I think not! So why would you call a smoke detector a smoke alarm?
A smoke alarm is a stand-alone device with a built-in sounder, a power supply, and a sensor. A smoke alarm is not connected to a fire alarm control panel, but may interconnect with other smoke alarms within the building.
A smoke detector is part of a system, has only a built-in sensor and sends information to the fire alarm panel.
What Types of Detectors are out there?
The two most common smoke detectors are ionization and photoelectric. The sensing chambers of these detectors operate differently to sense visible or invisible combustion particles from developing fires.
Ionization detectors use positively or negatively charged ions to determine if an area is safe. Once combustion particles enter the air, they alter the internal plates’ measurements to detect smoke. In an ionization detector, dust and dirt can accumulate, increasing the chance of an unwanted alarm. The characteristics of an ionization detector make it more suitable for detection of fast flaming fires.
A photoelectric detector uses a light beam passing through air. The smoke blocks or obscures the beam, or causes the light to scatter. The detector senses smoke by monitoring the light. A photoelectric detector is subject to unwanted alarms from light reflected by insects, dirt, drywall dust, and other forms of contamination. Photoelectric smoke detectors are better suited to detect slow smoldering fires.
Each type of detector can detect both types of fires, but their respective response times will vary depending on the type of fire.
But Wait, There’s More!
Sometimes a facility requires a more exotic detector for special conditions.
Laser technology smoke detectors are designed for areas that require extremely early warning of fire. They are ideal for clean rooms, computer rooms or telecommunication centers, or any area with mission critical operations.
Aspiration smoke detectors use a pipe and fan system to sense the presence of smoke particulates.
These detectors are a good choice in clean rooms, areas which contain highly flammable liquid and gases, or rooms with goods easily damaged by fire, such as electronic rooms.
Multi-criteria detection contains multiple sensors that separately respond to physical stimulus such as heat, smoke, or fire gases. An alarm signal is determined through advanced algorithms based on input from these sensors. Several types of multi-criteria detection are available. The combination of sensors offers faster response times to real fires as well as better immunity to nuisance alarms in challenging environments.
Combination carbon monoxide and smoke detectors improve installation time and cost as well as offering a more aesthetically pleasing final product. This device type provides separate signals for each event.
So What Now?
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Posted on: June 23, 2015