【 Weak current College 】 construction electrical fire design specially excluded in the frequently asked questions

For modern architecture, the fire is very important, and fire protection design is the building fire safety is very important, timely and accurate fire alarm, the correct extinguishing linkage, secure and reliable fire power, such as electrical fire design is particularly important.
First, power passenger elevator
According to the architectural design fire protection standard "and" senior civil building design fire protection standard for the relevant provisions, the electrical equipment should be used in a dedicated power supply circuit. Therefore, in General, design, big or small, often passenger elevator and separate power supply for fire ladder, the author believes that this is reasonable. From the perspective of fire, a multitude of electrical equipment, passenger elevator is very special. Because it is neither a fire-fighting equipment-fire must ensure that the power supply; also Unlike conventional air-conditioning and ventilating equipment – fire must be removed. According to the automatic fire alarm system design code of the relevant provisions, in confirmation of the fire that should passenger elevator is forced to the bottom, and then power it down. The passenger elevator in the confirmation of the landing run after fire, its power to ensure. To this end, the author believes that should passenger elevator as "quasi-fire-fighting equipment". When the building is not multi-elevator and room adjacent to the passenger elevator and a fire ladder with double the power circuit. If the separate power supply, the second group of dual power supply circuit. Because of the elevator room located on the roof, power supply range is large, consider factors such as the voltage drop, per wire cross section could not be reduced and combined with a set of dual-power loop, this will cause the distribution shaft arrangement is in the lead, the temperature rise higher, making safety and reliability of electricity supply. In addition, because the circuit number increases, substation outlet positions but also to increase, causing unnecessary investment in waste. For this reason, our local standards are ambiguous, as promulgated in 2002 Shanghai local standards of the House design standards "DGJ08-20-2001 has already expressly provided that the passenger elevator can fire ladder with a set of dual-power circuit.
2. lighting problems
According to the automatic fire alarm system design code, confirm that the relevant provisions of the fire, should be able to cut off the parts of the non-fire power. To this end, the design in General, the General will have a general lighting and resection. However, lighting is in emergency situations to keep people's stability. As a result of emergency and induction lighting and general lighting of illuminance, vastly, suddenly for general lighting, emergency and alone, there are induced by lighting may cause panic and confusion among, in particular, personnel are crowded places such as shopping malls, theatres, airports, stations, etc. Therefore, in order to ensure orderly and safe evacuation of the population, and guarantee the safety of firefighters, fires, burning layer after the confirmation of general lighting should not be removed immediately, but should be delayed for a period of time after resection. Delay time according to the places the nature, size, might flow density and other factors to determine. It is important to note that here the author emphasized that the General lighting not man-made immediately removed, but also eliminates the need to secure. Because it is not a fire-fighting equipment; also different from the above passenger elevator landing stage, even in the evacuation, general lighting is not a must, according to the specifications set of emergency response and induction lighting has been able to meet the requirements of evacuation lighting only the evacuation of the stage, on the stability of the human heart, there is no general lighting. And, when the workers at the conclusion of the evacuation, general lighting must be removed. In addition, to ensure electrical safety and prevention through the expansion of the electrical equipment, line of fire, general lighting power distribution cables should be used for flame retardant and should strictly follow the line of fire codes, compress, and its distribution loop fault protection should be set. Of course the hotel, Office building of the aisle, general lighting and emergency lighting illumination and induced by not very large, in fire upon confirmation, the immediate removal of general lighting, but should be appropriate to increase the contingency and the number of induction lighting to minimize illumination caused by poor people panic.
Third, the passage of fire shutter control issues
According to the automatic fire alarm system design specifications "section 6.3.8, evacuation channel fire shutter should be set fire detector unit and should use the following procedure to automatically control: smoke detector actions after the shutter down to pitch to 1.8 m; thermal detectors actions, the shutter down to the end. The use of different types of fire detector and signal to control, its aim is to improve the security shutter action, however, usually the reliability, the shutter function is used on both sides of the same, that is, both sides should be set the same fire detectors. If the above provisions do not have the conditions, as rigid set of different probes, one of the higher rate of false positives of the probe, but reduces the action of the security and reliability. As a large underground garage, which normally have the tail, and poor ventilation conditions, according to the specifications should be set heat detector, smoke detector is not appropriate under the above provisions setting temperature sensor — smoke detector unit to control the shutter, the probability of false positives. Moreover, this kind of "crying wolf" type of false positive more, a long time, easy to produce fire on duty of vigilance, this is very dangerous. As this author believes, should be the automatic fire alarm system design specifications "in" 7. fire detector selection "to set the detector and shutter detector selected one on each side of the same type and of different types may constitute detector control shutter, not deliberately constitute different types of detectors group. Because now the automatic fire alarm product performance and quality has been enhanced, in particular the analog analogical-probes and two probes at the same time, the probability of false positives is even lower. Moreover, this is also consistent with the automatic fire alarm system design specifications "section 7.2.10," equipped with linkage, automatic fire extinguishing system and single probe cannot effectively confirmed fire situation, the use of smoke detectors, heat detectors, flame detector with type or combination of different types. " Of course, meet the standard of choice for fire detectors provisions, should be preferred a different type of detector control fire shutter. Additionally, for channel fire shutter, probe set in what parts of the group, the specification is not made specific provisions. In the specific project, generally set at the nearby fire curtain, this is not the best choice. Because when away from the fire shutter farther on fire, the fire shutter cannot play timeThe alternate fire and smoke. To this end, the author believes that the detector should be "virtual groups", both in the fire zones, and not sure which several probes into probe group, but when the region any two detectors, fire curtain should drop to pitch to 1.8 m; when the third probe, fire shutter down to the end, do that, for most of the now using computer-controlled automatic fire alarm products, are perfectly feasible.
Fire curtain should drop to pitch to 1.8 m; when the third probe, fire shutter down to the end, do that, for most of the now using computer-controlled automatic fire alarm products, are perfectly feasible.