Detection systems smoke detectors

Smoke detectors are primarily used where smoldering fires can be expected and where electrical equipment is located indoors. Examples of their use are in offices and sleeping quarters, computer rooms, control rooms, electrical switchgear rooms, etc. Their response is typically faster than that of heat detection devices. Smoke detectors are more susceptible to false alarms and usually multiple detectors are required to be in alarm before an extinguishing system is activated. 

As indicated above, the spread of fire and smoke can be controlled by both passive and active means. On the one hand, the measures include separation of buildings com-partmentation fire walls fire doors fire and smoke shutters controls on air conditioning and pressurization of critical areas such as stairways and, on the other, detectors and alarms extinguishers hose reels and sprinkler systems. Smoke detectors generally detect fire more quickly than heat detectors. 

Security and safety Intruder alarm Security systems Fire detection systems, with sensors for - temperature - toxic gases like CO, C02, exhaust gases, smoke, etc. - combustible gases like CH4, C2H6 flame detection, fire detectors, caravans with gas detectors, etc. 

Sprinkler systems are an effective way to contain fires. The system consists of an array of sprinkler heads connected to a water supply. The heads are mounted in a high location (usually near ceilings) and disperse a fine spray of water over an area when activated. The heads are activated by a variety of methods. A common approach activates the heads individually by the melting of a fusible link holding a plug in the head assembly. Once activated, the sprinklers cannot be turned off unless the main water supply is stopped. This approach is called a wet pipe system. These systems are used for storage areas, laboratories, control rooms, and small pilot areas. Another approach activates the entire sprinkler array from a common control point. The control point is connected to an array of heat and/or smoke detectors that start the sprinklers when an abnormal condition is detected. If a fire is detected, the entire sprinkler array within an area... 

When dealing with an entire fire detection system that utilizes more than one type of detector, a Detonator Module greatly expands the flexibility and capability of the system. An individual Detonator Module can accept multiple inputs from UV and IR controllers, other Detonator Modules, manual alarm stations, heat sensors, smoke detectors or any contact closure device. In the event of a fire, any of these devices will cause the internal fire circuitry of the module to activate the detonator circuit, sound alarms, and identify the zone that detected the fire. When properly used, a Detonator Module will add only one millisecond to the total system response time. See Figure 8 for an illustration of a fire detection system with a Detonator Module. 

Smoke detectors are employed where the type of fire anticipated and equipment protection needs a faster response time than heat detectors. A smoke detector will detect the generation of the invisible and visible products of combustion before temperature changes are sufficient to activate heat detectors. The ability of a smoke detector to sense a fire is dependent on the rise, spread, rate-of-bum, coagulation and air movement of the smoke itself. Where the safety of personnel is a concern, it is crucial to detect a fire incident at its early stages because of the toxic gases, lack of oxygen that may develop, and obscuration of escape routes. Smoke detection systems should be considered when these factors are present. 

Alarm systems can be integrated with fire detection systems, intrusion detection systems (IDSs), access control systems, or closed circuit television (CCTV) systems, so that these systems automatically respond when the alarm is triggered. For example, a smoke detector alarm can be set up to automatically notify the fire department when smoke is detected, or an intrusion alarm can automatically trigger cameras to turn on in a remote location so that personnel can monitor that location. 

Early detection is essential. The placement of detectors inside cabinets can significantly reduce the time to detection. An early warning high sensitivity smoke detector (HSSD) smoke detection system can be used to detect incipient stage fires and allow planned repairs prior to equipment failure. Hence, fire suppression may not be required. 

Chapter 9 Fire protection systems suppression and detection systems (including sprinklers and smoke detectors). 

Smoke detectors are particularly useful in those situations where the fire is likely to generate a substantial amount of smoke before temperature changes are sufficient to actuate a heat detection system and before a fire eye will detect a flame. Smoke detectors use a photoelectric beam between a receiving element and light source. If smoke obscures the beam an alarm is sounded. There are... 

Automatic fire detection systems are used in most industries today. They warn of the presence of smoke, radiation, elevated temperature, or increased light intensity. Some detector types are ... 

Fire and Smoke Detection Fire detection systems and alarms should be considered in hazardous locations. These include gas, thermal, smoke detectors, thermal detectors, as well as IR/UV flame scanners... 

Confinement of Smoke and Fire FIRE-DETECTION AND -ALARM SYSTEMS Heat Detectors Smoke Detectors Flame Detectors Gas Detectors... 

Area smoke and heat detectors. Hazardous production material storage rooms are required to have a supervised smoke detection system in accordance with the above UFC requirements. We recommend the installation of heat detectors in all electrical rooms. 

A laser based and microprocessor controlled high sensitivity spot type smoke detector. It appears similar to an ionization smoke detector. It works on the light-scattering principle but with 100 times greater sensitivity than ionization type detectors due to the use of laser. It achieves a greater sensitivity because the laser can detect extremely small products of an early fire (which cannot be seen by the human eye) therefore it is comparable in detection capability to aVESDA system (see the next section). At this time, it is considered the highest sensitivity spot type smoke detector available. Common applications include critical control and communication facilities. 

Leak detection plays an important role. Wire detection has been developed in many countries. Recently Super Phenix has been equipped with "Sandwich detectors" to cover welds on the piping exceeding 200 mm in diameter, on which insulating material may react with Na and prevent it from getting into contact with the classical wire detection system. Other detection systems such as flame spectrometers and smoke detectors are commonly used. The objectives pursued are the following ... 

All FRRSs should be fitted with an automatic selfclosing device. In cases where self-closing would be a hindrance to normal use, they can be held open by a local heat detection release mechanism such as a fusible link particularly where a FRRS has been permitted across a means of escape route. All doors installed in compartment walls which need to be held open in normal use, should be fitted with an automatic release mechanism which is connected directly to a local or remote smoke detection system and not rely on local fusible link for operation. The smoke detection system, if local, should have the detectors mounted on both sides of the compartment wall and should activate both visual and audible warnings and cause the door or shutter to close automatically without any delay. 

In this example a sensor (e.g. an automatic fire detector) is activated by combustion products such as smoke, heat or combustion gases. After activating the control unit (e.g. a fire alarm or detection system), it initiates programmed Controls of Fire Protection Systems (CFPS) or activates other actuators in the building. An actuator is for example a... 

Smoke detection systems should be installed in all electrical and switch rooms. The detector location should take into account the HVAC system fitted to the room. 

It is important that the tests are realistic and that they cover all subsystems to check the availability of the system as a whole. The fire and gas detection system, for example, is tested all the way from the detector, which is activated by gas, light or smoke, to the display in the central control room. 

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