Some beam detectors may include a small reflector that is mounted opposite the transmitter/sensor, so only one device needs to be wired. They have a wider operating temperature range than typical spot detectors and work well in colder environments, such as cold storage warehouses, sports arenas and high-ceilinged areas.
A duct smoke detector is a device or group of devices used to detect the presence of smoke in the airstream of ductwork sections of the HVAC air-handling systems in industrial/commercial facilities. Duct smoke detection assists in preventing the spread of toxic smoke and combustion gases and also can be used to assist in equipment protection applications.
Made to operate in air velocities from 100 to 4,000 feet per minute, some photoelectric duct smoke detectors utilize a pivoting housing that fits both square and rectangular footprints on round or rectangular ductwork. These detectors provide the superior false alarm immunity necessary to reduce callbacks in duct applications prone to nuisance conditions. For challenging or unique duct smoke applications, high-sensitivity duct smoke detectors use a laser sensor to provide very early warning of fires to protect high-value assets and mission-critical operations from fire and the spread of damaging smoke through air management systems.
NEMA 4-rated watertight duct smoke detectors are built to operate on rooftops or other areas that are exposed to water or the weather without the need for bulky or costly enclosures. Many of these detectors can operate in airflow speeds from 100 to 4,000 feet per minute.
Multi-criteria sensing fire detectors
One solution to detect a broad range of fires quickly would be a multi-criteria detector that uses photoelectric particulate detection in tandem with sensors that detect other products of combustion, such as carbon monoxide (CO) and light (infrared). Together, these signals are cross-referenced by an onboard microprocessor that uses algorithms to “process out” false alarms while enhancing the response time to real fires.
Intelligent multi-criteria detectors monitor more than one product of a fire in order to achieve higher levels of sensitivity, detect a wider range of fires or improve accuracy. There are a variety of multi-criteria fire detectors, some combining up to four sensing technologies—smoke, CO, heat and infrared—with intelligent detection algorithms.
This type of detector is ideal for challenging applications where typical spot detection may initiate nuisance alarms. Places where nuisance alarms would be costly or dangerous—such as theaters, medical facilities, dormitories, senior living centers, financial trading centers, telecommunications networks and manufacturing facilities—could especially benefit from this type of detection.
Another intelligent multi-criteria detector combines photoelectric and thermal sensor signals to provide early and accurate fire detection. Some may automatically adjust sensitivity within specified parameters, further enhancing response speed and accuracy. Then there are multi-criteria detectors that combine smoke detection and CO detection in one unit.
Heat detectors provide property protection against fire and for non-life-safety installations where smoke detectors are inappropriate. Heat detectors are applicable for areas with unsuitable conditions for smoke detectors, including places that experience rapid changes in temperature or where high ambient temperatures exist, such as storage facilities, garages, mechanical rooms, commercial kitchens and other service areas.