【 Weak current College 】 large clothing wholesale market fire design---Power By 【 China power house network 】

In recent years, with the rapid development of market economy, have built many large garment wholesale market. Zhuzhou Hunan province first building large clothing wholesale market city, nearly two years as the transformation of the old city, the development of the investment project, Zhuzhou and construction of a number of large garment wholesale market. But in such markets in accordance with the existing fire technical specifications are checked, exposed the specification of the imperfect nature of the problem. In accordance with existing national fire technical specifications, construction, design, fire authorities in the implementation of the specification has a relatively large differences. In this author combined with practical work experience, according to technical specifications and technical data on this type of market fire design made personal views, I hope to do this kind of market fire design plays a valuable role.

1. the characteristics of such market

(1) building area. Class market area are in the tens of thousands of square meters or more. The present building Zhuzhou in several market building area is over at 50000 square meters, among which the Mandarin dress Plaza total building area is 200000 m2;

(2) fire load. Class market generally separated booths, each booth area of 20 – 200 sqm. The front of the booths for hanger hanging sample show, rear horizontal stacked pending wholesale of clothing. From Tianjin fire Research Institute of experimental results can know, 70kg mixed quality costume flat stacking in l m2 area of peak combustion heat release rate, while for 960.00kW such market each booth are stacked hundreds of kilograms of clothing. Especially in the sales season is stacked in the stalls of the garment, the combustion heat of combustion is very alarming;

(3) to open the window area is small, poor natural smoke exhaust capacity. This type of market stalls for layout and create business climate, open Windows are closed or supposes a fixed window. Unable to open the window using external natural smoke exhaust;

(4) officers, fire danger, fire extinguishing is difficult. After causing fire death group and group of major economic loss. This type of market stalls layout by external walls, generally the original settings window blocking, difficult to access internal market.

2, fire safety design requirements

2.1 fire compartment smoke control design

2.1.1 fire compartment design requirements

Pursuant to the architectural design fire protection standard article 5.1.1 request: multilayer market fire partitions on each floor area allows for 2500 sqm, equipped with automatic sprinkler facilities can amounting to 5000 m2. under the tall buildings design fire protection standard article 5.1.2 request, senior market ground fire partitions on each floor area the maximum allowed is 1000 ~ 1500 sqm, equipped with fire alarm systems and automatic fire extinguishing system can be up to 4000 square meters; the underground market each floor fire compartment area the maximum allowed is 500 square meters, equipped with fire alarm systems and automatic fire extinguishing system can be up to 2000 square meters. Conduct fire partitions generally use fire shutter and separated by a firewall. After the ground no window market fire risk analysis found underground building fire hazard in the United States will also be ground without window room fire danger rating the underground buildings category. So do not set the window's market in the area of fire partitions should be determined according to the requirements of underground construction.

Conduct fire partitions may be separated by a firewall and fire shutter. Fire shutter is generally divided into two categories: the first is the General fire shutter, due to the non-insulated protection measures to detect only through measuring its back fire surface a distance of radiant heat and slat is put fire to judge its fire resistance and therefore does not meet the requirements of the fire prevention Division separated. In use should be set on either side of the shutter independent closed sprinkler system or water protection, their duration should not be less than fire shutter are replaced by the fire resistance of the firewall. In practical work as a result of regulatory requirements, automatic spray cooling system or curtain system as a stand-alone system, combined with cooling water consumption is too large, the basic hard to adopt the construction unit. Zhuzhou has built and will be located in one of the market in this way for fireproofing. The second category is super fire shutter, the use of special materials, detection is back fire surface temperature rise as its conditions of fire resistance, it can meet the requirements of the fire prevention Division separated. At present the market of VAP steel fire shutter, dual-track double curtain inorganic composite fire shutter, evaporative steam mist fire shutter, and so are in this category. This type of market is draped over the booth, fire partitions can be part of the pitch of the partition to the firewall. This only needs to be set on the sidewalk Super fire curtain separated, significantly reducing costs. For the ground no window market fire partitions by underground building standards Division of the increase in cost will not be increased too much.

For upper and lower layers in the market in the adjoining corridors, open stairs, escalators, etc opening area for vertical fire partitions, specification requirements and horizontal partitioning. Vertical fire partition is essentially the spread of the fire's heat convection, radiation and conduction of two fire spreading way because of the separation slab and it is difficult to achieve. The horizontal partition also consider fire spread of heat radiation, heat conduction. Therefore horizontal partitions and vertical fire partition requirements should not be treated equally. For the vertical fire partitions should relax, as long as they can to prevent fire spread vertical thermal convection can be the result. But setting should be the judgment of fire resistance of side-facing business. In Mandarin commercial square vertical fire in the Hall to separate design from the market hall area is 2000 m2, width up to each of the porch, and the Central Hall 4m set mechanical smoke extraction facilities. After taking in the Central Hall of the corridors in the set quick response sprinklers and smoke outside in the corridor, along with fireproof glass set smoke hanging wall, to cancel installations fire shutter design. This kind of design in aiwanting Hotel Central Hall also adopts. For other large central hall is also available in this design.

2.1.2 smoke design requirements

Because of the architectural design fire protection standard "on the market without smoke design requirements, designers in the designIn this design. In Zhuzhou built multi-storey market there is no setting. High-rise building market of fire safety design of tall buildings in the design fire protection standard, though, but in general the construction at the beginning of the designers to consider making use of the exterior Windows of natural smoke, smoke extraction facilities is not set. However in construction or completion because of market stalls set requires a window block for natural gas. In such markets is mainly accumulated clothing apparel General to cotton, linen, silk and polymer compounds for raw materials, combustion will produce a large amount of smoke. Coupled with market natural ventilation and smoke conditions are poor, the fire because of inadequate combustion produces large amounts of smoke that seriously affect the evacuation and fire fighting. At the same time because of the high temperature of the flue spread caused rapid rise fire temperature, shorten the flashover occurs, accelerate development speed, increased fire fires more difficult. Design engineering of smoke prevention aims to prevent fires in large amounts of smoke that prevent the rapid spread of smoke, make sure that the evacuation and rescue. In NFPA requirements for personnel in concentrated place should be for smoke control design. So I think this kind of market is the need to design mechanical smoke extraction facilities.

Market of mechanical smoke control mode are the following:

(1) natural ventilation, smoke. Exhaust smoke in a very short time, the ideal visibility within the aisle, better airflow, smoke extraction time is short, for evacuation is very favorable, unfavorable for fire fighting, reducing fire losses. Exhaust volume specifications for 60m3 (M2 · h) and 120m3 (M2 · h);

(2) mechanical ventilation, mechanical smoke extraction. Does not have natural ventilation conditions, mechanical ventilation, mechanical smoke extraction. For aboveground and underground markets free form should be used in this design. The amount of exhaust smoke control system by the smoke partition area exhaust volume 60m3/(M2 · h) and 120m3/(M2 · h) calculation of smoke, air supply and exhaust smoke partition by burden of 50 per cent. According to the specification requires a smoke partition to 500 sqm, exhaust design calculation according to specification, design and exhaust volume is large, the effective sectional area of air duct up to 1 m2, smoke exhaust vents in the effective cross-sectional area of 1.67 sqm. So for the wind tube footprint more than 1 m height. By improving the building storey resolve marketplace business Hall height will greatly improve the construction cost.

The preceding calculation does not take into account the sprinkler installations, the actual exhaust of such market is set for automatic sprinkler installations. But you must consider the effect on exhaust ventilation, nozzle spray out of the water will reduce the temperature of the fire, may reduce flue gas emissions. Addition of water the surrounding gas and air conveying of smoke rushed to the ground, in setting a sprinkler installations construction set mechanical smoke extraction facilities of mutual influence of direct data, has been focus on scientific research '. Press fire simulation model CFAST and simulation model of evacuation, in Fegress sprinkler systems and smoke extraction system, joint action, the amount of exhaust smoke control system in the exhaust smoke partition construction area is 36m37 m2 · h), you can always keep the smoke of the interface, you can guarantee above 2m personnel to have enough time to evacuate to a safe location. A test access for underground commercial business Hall smoke quantity by 72m3/(M2 · h), you can reach the exhaust. In the automatic sprinkler system in place for automatic sprinkler systems of water will reduce the temperature of the hot flue, which may reduce the amount of exhaust smoke, and out of the water there are suppressant. Result in automatic sprinkler systems and smoke extraction system, joint action, the amount of exhaust smoke control system by the smoke partition area exhaust volume 36m3/(M2 · h), a building area of air by 24m3/(M2 · h) calculation of air. In Mandarin commercial Plaza exhaust design due to the relatively high architectural layers on wind pipe diameter size has no effect, so by 2000x60m3/(M2 · h) determine the amount of exhaust smoke (smoke partition dividing by 2000 © o).

As a result of such market are set air conditioning system, ventilation, air-conditioning systems and mechanical smoke extraction system and in the specification is allowed. After the design calculation was informed that the exhaust duct effective sectional area and exhaust duct, air supply of air duct is similar to the effective sectional area, so the design of mechanical smoke extraction system can use ventilation, air conditioning systems and combined mechanical exhaust system. Design generally use ventilation or exhaust system with air duct for the exhaust pipe. But the air pipe should be consistent with the requirements of the exhaust duct. For use with the exhaust system can be considered high temperature resistance, high strength, ≥ 280 ° c can work continuously for more than two-speed 30min exhausting axial fan, usually slow running exhaust smoke, fire and high speed. For use with air supply systems wind pipes combined should end set air fan and exhaust blower, separated by fire damper. Usually, open to the air blower of fire dampers open, open the exhaust fan of the fire damper is closed, air blower starts blowing; fire ventilation fan and open to the air blower of fire safety valve closed, open the exhaust fan and exhaust fan exhaust valve opening of fire.

For combination should note the following:

(1) shall be adopted by the alarm system control shutting down function of the air;

(2) of the exhaust port usually close, fire control system;

(3) should the relevant technical requirements of the accounting of the air and exhaust the effective sectional area of the mouth, reasonable arrangement of air and smoke exhaust vents;

(4) and the exhaust system common fan and exhaust blower power supply circuit should fire power exhaust fan power supply circuit in peacetime, fire fire power supply circuit switched to supply;

(5) exhaust port setting automatic smoke fire dampers that can turn off the gas temperature exceed 280 degrees centigrade of exhaust outlet, the entire system can still continue to work to ensure that the overall effect of smoke, smoke partition size specification requires ≤ 500 ㎡. This provision shows that you can know, divided by 500 m2 specification mainly onTaking into account the effect on exhaust shaft too many architectural design. For large shopping malls in the ceiling on excessive smoke vertical walls difficult, so you can actually increase the smoke partition size. In Mandarin dress square with 2000 © o for a partition, each partition separate smoke exhaust system. In the technical specification for the Shanghai area will also be in 2000 m2 of the area for a partition. After analysis of smoke hanging wall height of floor to ceiling height of 20 per cent of the best, according to business Hall height 3 ~ 4m calculation of smoke vertical wall of SAG to 60 ~ 80cm suitable. Taking into account the characteristics of the market for the use of automatic smoke vertical wall, usually vertical panels in the ceiling, wall and hanging installation of fire detector, in the event of fire, fire detectors and alarm, automatic smoke while driving down wall opening drop 90 °. Vertical wall to smoke in the hot smoke stream is not compromised can guarantee reserve smoke cartridge is not compromised, you should use high-temperature solid inflammable materials do vertical wall of smoke. In order to market appearance can also use fire protection glass of the vertical wall of smoke.

Smoke-proof design mainly on evacuation staircases and front room air distribution, according to the specifications for the evacuation of stairs every layer 2 settings louvered air. Due to the specification for the first room air only requirements on each floor, there is no clear how to set up, easy to cause errors in the design. Front room air is determined according to the open door 2 ~ 3 to ensure that the door when a certain speed, fire evacuation belongs to a continuous evacuation, when all doors are opened, if possible louvered air, if insufficient air will not be able to guarantee the necessary speed of the door. So in the design of the front room air should be used with electronic valve changbishi áir, fires burning by the control center on a layer and room air, 20 layer above the layer 3 of the open air.

Door wind speed specifications required for the 0.7 ~ 1.2m/s, depending on the door effectively prevent smoke affects the required evacuation speed study finds, door wind speed to achieve 4m/s can effectively control smoke evacuation, in the design recommended 4m/s design parameters.

In the actual design of the buildings in the exhaust system design and other facilities system design should follow each fire partitions as an independent unit design, so as to ensure the facilities in the fire safety.

2.2 evacuation design

2.2.1 evacuation and the determination of the total width

The current implementation of the national norms of occupiers load indicator for approved normative's long, difficult to rationally determine capita area of design. In the shopping centre in NFPA101 Hall of personnel density 2.8 m2/person. According to Suzu city existing wholesale market estimation (about one month before the Festival) at the market place at high density as 1.8 m2/people. I passed on some existing market analysis, recommendations for ground part 2 © o/person for the purpose of calculating the density index, underground parts according to determine 1.5 m2/person.

Business Hall of actual area should follow the specific project design to determine the business of building area. At design time in order to reduce the total evacuation width, many designers use every layer of the building area is multiplied by 34 per cent (the store building design code (JGJ48-88) 3.1.2 requirement: construction area > 15000 © o, business area should > building area x34% to determine the business area, but also by how many people each pitch to determine the total number of persons. In Mandarin commercial square start design, designers to reduce the total evacuation width per booth 2.5 calculation, the author believes these calculation methods used by unreasonable. As 34 per cent only business in business, storage, assisted the three parts of the building area of distribution in proportion to each pitch according to calculation of 2.5 sources not justified. So in design review in these calculations are not being used. Calculate the area of press for the customer (including the store staff) stay and activities of the area determined. According to the analysis of the many, large commercial business Hall of residence for workers and the activities of computing is about its building area of 50%, multiplied by a conversion factor for the calculation of the number determines the evacuation, and then calculate the total width divided by the evacuation of the index is calculated from the total evacuation of width.

2.2.2 evacuation distance determined

For multiple-tier market, the market at any point to the nearest safe export of straight-line distance to 40m. automatic sprinkler systems, evacuation distance can be increased to 50m, senior market in the senior civil building design fire protection standard of requirements for the senior market 30m. in case of fire, the fire sprinkler systems turn on sprinkler, mechanical smoke extraction facilities, will start the exhaust extension of evacuation time. When the evacuation speed must be increased by the evacuation time. In NFPA101 clearly established two exit between the maximum distance from the building or the zone of maximum diagonal length of the reference. By 4000 square meters of area (rectangle 50x80) diagonal length can reach 94m. In the architectural design fire protection standard section 5.3.8 provisions mentioned in the notes, set an automatic sprinkler system, evacuation distance can be increased by 25 per cent, as a strengthening of security conditions, allow the appropriate adjustments, to design a certain flexibility, senior market evacuation distance can relax. For automatic sprinkler systems, fire alarm systems, mechanical smoke extraction facilities of high-rise, market, evacuation distance can be relaxed to 42m, to large market design also brings flexibility. For underground part and larger shopping malls, you can consider setting the secure evacuation corridor to solve the problem of evacuation distance. In the proper place of a closed evacuation staircases sidewalk connections, set in the aisle of positive pressure ventilation system smoke.

2.2.3 automatic sprinkler system design

Currently has built and will be built in market design of automatic sprinkler systems are the ordinary automatic sprinkler system (common type nozzle, hydraulic calculation by the sprinkler system design specifications "section first 5.0.1Conventional sprinkler system). However I believe that in this type of market design normal sprinkler system does not meet the actual requirements, difficult to successfully control initial fire. There are such markets in General and in the ceiling, fire sprinkler system design specifications "section 6.1.3 clause description do not recommend the use of standard nozzle. The reason is in the suspended ceiling installation such nozzle, spray sprinkler serious disruption, strength will drop by 40 percent, severely weakened the ability of the fire extinguishing system. United States provisions in the personnel-intensive sites must all adopt esfr, reason is the fire main by fire sprinkler systems, fire personnel must leave the scene of the accident as soon as possible. Quick response sprinklers in fire-fighting, and in the early days of reflection for early fire auto-alarm, the fire brigade arrived timely alarm, rapid fire, fire does not produce large amounts of toxic fumes, in favor of personnel for the early withdrawal of the scene. The fire brigade arrived at the scene as soon as possible after the initial fire fighting personnel, without having to force on evacuation and rescue personnel, missed opportunity of the initial fire fighting. Fast action at an early stage of fire fire system can inhibit the spread of fire, and Moreover such market clothing are piling up, the General level of the water spray nozzles are difficult to reach the burning surface fire could not be effectively controlled.

In such a market of sprinkler system ESFR sprinkler for early fire suppression is valid. For hard-to-use ESFR sprinkler or should flow 2.21/s of the nozzle, as the effects of the action in the area of water sprinkler head determine. The author in audit meeting Asia Business Plaza, preliminary design in the market of automatic sprinkler system design for flow 2.21/s of the nozzle, the designer's identity. ESFR (EafiySuppressionFast-Response) nozzle, known as early suppression fast reflect the nozzle. It is a fast-response of the nozzle, the response to the role of fire suppression. ESFR sprinkler is fire suppression, instead of the control of fire (except ESFR sprinkler outside other quick response sprinklers for fire suppression). According to the definition of NFPA13 fire suppression is fully water directly through the combustion flame Jet to the surface, obviously reduce flame heat release, prevent the re-growth. ESFR sprinkler reaction speed is the fastest of nozzles, high flow, big drops of water, the high rate of water can penetrate the burning flame, go directly to surface fire. This sprinkler fire-extinguishing system design parameters from "fullscale" or "largescale" real-scale fire test. The success of fire sprinkler hydraulic parameters can be used for ESFR sprinkler fire-extinguishing system design parameters.

2.2.4 fire electrical design

(1) design of automatic fire alarm system. Automatic fire alarm system is an intelligent, bus and integrated whole. Currently, many choose full bus automatic fire alarm system photoelectric smoke detector. But the whole bus system has a high rate of false positives, false negatives, for a variety of fire-fighting facilities control difficult. For this type of construction area, detection point and control facilities more features, based on a variety of automatic fire alarm system performance analysis, using the intelligent fire alarm system is more reasonable. Intelligent automatic fire alarm system with probe will fire the smoke, temperature, and other analog form together with the external environment parameters associated with the transmission to the alarm, the alarm again based on the data obtained by reference to the internal storage of large amounts of data to determine if there is fire, addresses the current automatic fire alarm system of logarithms (false positives, false negatives). At the same time, the linkage of automatic fire alarm and fire extinguishing system is made of two bus (or bus) to implement a system of information transmission, to the engineering design, installation and maintenance of a great convenience. And building air conditioning, electricity, water, lighting, security system and other public facilities and other public safety and management system are combined into one overall, building automation and management systems, to provide a central monitoring and intelligent decentralized management play a greater role;

(2) fire emergency lighting system and evacuation instructions system specification on fire emergency lighting illumination requirement in practice 0.5Lx. found this illumination to evacuate the required illuminance requirement when, while fire emergency lighting more settings in the ceiling, fire by smoke have a greater impact. Based on fire evacuation when the behavior found, enhance the illuminance can reduce staff fear. The author in auditing requires designers to illumination to 15Lx, such market fire emergency lighting generally use fire power supply circuit power, increase the illumination will not increase the cost of project. Fire emergency lighting system power lines should be concealed, the application should also be wearing steel brushing fire-retardant coatings protection, to ensure that fire not affected by the fire in the early days.

Specification required evacuation signs set out in the following parts, 1m market particularities practical engineering more settings to the ceiling, the evacuation instructions. Proposals, in practice the special evacuation signage is set in the partition wall between stalls, at the same time set on the sidewalk surface emitting evacuation signs.

3. concluding remarks

Due to the large clothing wholesale market and the general store in fire phenomena in large differences, many early on the market in the construction of the internal design of uncertainty and the existing fire technical specification on this kind of market does not explicitly require fire design, or some provisions in the actual implementation in the design of great difficulty, thus responding to the market the characteristics when the fire broke out scientific analysis, design and implementation of the science of fire, the introduction of new technologies, new equipment, enabling this type of market fire design smarter and more scientific.