How to choose the fire detector Law The component of a fire alarm system that people are more familiar with the sensor. Although most consumers are familiar with the devices in their homes called smoke detectors, many would be surprised to know that there are many different types of detectors on the market. These types of detectors vary in what they detect, how they detect, how they are managed by the fire alarm system itself and how they are fed. In addition, there are dozens of manufacturers of sensors and they vary greatly in price, depending on their characteristics and functions. As such, those looking for a detector of a fire alarm system is facing a plethora of choices. (NOTE: Since all the sensors begin the process of placing a fire alarm system in alarm mode, they are one of what may be several devices on the system known as "triggering devices". )
The first decision to make when selecting a sensor system is to determine what needs to be detected. The sensors detect fire or smoke or heat. (You guessed it - the first smoke detectors are called "detectors they are called heat.) Smoke detectors triggered an alarm when a sufficient amount of smoke entering the room of smoke alarm. Furthermore, heat detectors are equipped with sensors that detect heat and / or an increase in temperature of a certain amount. For example, a heat detector may be designed to go into alarm if either of the following conditions are met: 1) the ambient temperature at the detector is 130 degrees Fahrenheit or 2) temperature at the detector increases of 15 degrees Fahrenheit or more during a period of one minute. The first type is known as a "fixed temperature" heat detector, while the second is known as a "rate of rise heat detector. (There is also a combination fixed temperature / rate of rise detectors on the market.) Because there are several factors that could cause a fire, but not cause a rise in temperature at the location of the heat sensor, it included the distance between the fire and the heat detector normal variations of temperature in the building, heat detectors are not as susceptible to fire, smoke detectors and are therefore not considered reliable enough to be considered such as safety of life "devices. As such, they are considered best suited for applications property protection. They can also be used in places where there is normally a lot of dust or smoke in the air, causing false alarms triggered by smoke detectors.
Once the decision of what is done to detect, the decision of how to detect it is the following. In the case of heat detectors, there is usually only one method used to detect heat. A heat detector will have two resistors which are sensitive to temperature (called "thermistors") on an electrical circuit in his room. When the temperature rises to a point high enough (or, if rates rise heat detectors, fast enough during a given period) to deteriorate a resistance, the circuit is broken and the detector heat goes into alarm. Smoke detectors sense smoke in their rooms in one of two ways. Photoelectric smoke detectors have both a light source and a light sensor in their rooms. In their normal state, the light from the light source is not in contact with the light receiver. When smoke enters the chamber, however, some rays of the source of light scattering, this contact with the light sensor and put the detector in alarm. Ionization smoke detectors in air showed in their rooms. The air charge is used as electrically conductive part of the room to another. When smoke enters the chamber, it reduces the load in the air, opening the circuit for current to the detector in alarm.
The third differentiating factor when considering a fire detector for a fire alarm system is the method used by the control panel fire alarm handle.
Posted on June 4, 2010.
