【 Weak current College 】 public entertainment in smoke technology application research

As China's economic construction fast development and people's standard of living, the people's material and cultural life is becoming richer, dance halls, karaoke Hall, bars, nightclubs, music Cafe, Internet Cafe, a growing number of public entertainment, bring comfortable pleasant at the same time, it has also brought a fire hazard. These sites focus, in the event of fire, the fire spread rapidly, evacuation difficult to produce large amounts of toxic gases, but we all know that the fire caused casualties, most is not the result of the direct effect of the fire and the fire of smoke and toxic gas.

I. flue gas public entertainment in the spread of

Fire smoke in the room, up went the process after the ceiling level around and surrounding the proliferation of building envelope of barrier and cooling, along the wall down mobile trend, smoke constantly arise, the upper part of the smoke layer gradually thickening, arrived at the door and window openings below, through an open door and window openings spread to the outdoor and corridor. So when the smoke layer and doors closed, and will continue to increase in thickness, and indoor temperature rise to a certain value (typically 200 ~ 300 ℃), the glass doors and Windows, smoke from the doors and Windows of the gap to the proliferation of outdoor and corridor. Flue gas flow in the corridor is a laminar flow state, this flow process has two characteristics: first, the flue gas flow in the upper, the air flow in the lower deck. From the room to smoke within the corridor, began under ceiling affixed in flow, flow speed per second 0.5 ~ 0.8 m, smoke layer such as affected by beams and other highlights from obstacles, and outdoor air ventilation and air conditioning system airflow or interference, its laminar flow of distance will be shortened by turbulent state. Second, the smoke layer thickness in certain processes can be unchanged from the burning room in the corridor from the flue gas outlet, typically up to 20 m to 30 m distance from the left and right comparison when flue gas over long distances, on the one hand, there is always a cold air mixed, on the other hand as a result of the corridor ceiling surface and side walls, and other building elements of cooling, gas temperature gradually declining, on both sides of the flue gas side along the wall, and finally just started to fall in the middle of the cross section of the corridor for a close circle of air flow unit.

Flue gases along the staircase and the elevator shaft, shaft pipe wells, mobile, outdoor and indoor air temperature is higher than the air through the building and surface following layers into the wall, as the indoor and outdoor air capacity to generate buoyancy. Building upper pressure greater than outdoor, indoor air will flow to the outdoors, the lower the pressure is less than outdoor pressure fresh air will flow to the Interior. In high-rise building stairwells, Elevator shafts, as well as various pipelines also appears in the chimney effect, this phenomenon usually on building air flow plays a key role. In case of fire, burning flown by a large number of calories, the indoor temperature rises rapidly, building chimney effect even more significantly, the fire spread rapidly, straight up speed of about 3 ~ 4 m/s.

Second, the use of natural smoke exhaust method

Natural gas is the role of the natural forces, the indoor and outdoor air exhaust stream, the main advantage of Windows can be opened or balcony, concave to exhaust by the gallery. In this way economic, simple, easy operation, do not use dynamic and specialized equipment, always use double as ventilation, fire is not affected by the outage. In the code for non-mandatory requirements some smoke extraction mode can give priority, as in the following circumstances: (1) located in the underground building evacuation aisle or four layers and four-layer multilayer civil construction building evacuation of public entertainment in length within the aisle 40m or other required smoke room. (2) is located in a building and building height more than two types of building 32m public entertainment evacuation in length within the aisle 60m or other required smoke room. (3) building height 32m following second class building public entertainment evacuation aisle or other required smoke room. (4) air defence project area less than 50 square meters room; the total length is less than 20m evacuation of the aisle. However, in the design-time must take full account of the effective opening area area, ensure the multilayered and high-rise buildings in the public sidewalk, entertainment room can not open the window size is smaller than the room, aisle 2% of the surface area, the defence of public entertainment natural smoke exhaust port area is greater than the smoke partition size of 2%. At the same time, natural smoke exhaust port by way of the wind, and other factors, in the event of an air pressure of the exhaust gas is very difficult, especially in the lower area of the building, the fire if the exhaust port direction and wind on the contrary, causing smoke diffusion in buildings, rooms, corridors, stairs or evacuation of former rooms clustered smoke, seriously affect the design of evacuation, when you want to be taken into account.

III. application of mechanical smoke extraction methods

Smoke is the use of smoke machine forced flue gas pumped out, thus reducing the protected area of concentration in flue gas, smoke wall (active or fixed smoke wall), exhaust port (with exhaust valve exhaust port), fire smoke exhaust valve, exhaust and smoke machines and exhaust outlet. This way you can make up for natural smoke exhaust system mode, for drain evacuation aisle, fire room smoke has a significant effect. Therefore, the relative to public entertainment extremely applicable, at the same time, the smoke is divided into partial flue gas exhaust and set two ways, local exhaust is in each of the parts needed exhaust independent direct exhaust smoke machine, this way because the investment is high, smoke machines, maintenance management is too much trouble to costly and only applies to cannot set the chimney of the old buildings or renovation; concentrated smoke exhaust system is a building divided into several zones, each zone settings through smoke extraction machine, smoke exhaust duct. While in public entertainment settings the way you smoke must take account of the level and the actual multi-storey building; it is located in multi-story building and civil engineering of public entertainment, in order to ensure good air environment within the workplace, are equipped with a ventilation system equipped with exhaust piping facilities, the best way of using local and smoke, combined with the ventilation system, choose a reasonable increase in the number of smoke machines, electric smoke exhaust outlet normally opened and to ensure that the ventilation system to meet certain fire safety requirements, while rowSmoke Robotics and public entertainment venues of the automatic warning devices do not have to set the linkage between individual devices such as fire power, reducing the overall cost of the automated system. Usually smoke machine and exhaust air operation, as the exhaust air conditioning system, effectively ensuring the normal state of fire fighting equipment, fire, fire through linkage control center switches to fire smoke condition. It is located in the building of public entertainment, smoke control facilities audit, public entertainment can be divided into separate zones, centralized exhaust by high-rise building set in the exhaust duct smoke.

4. ventilation and smoke extraction system of both

Smoke control systems and the use of ventilation and air-conditioning system, not only can reduce footprint, saves capital cost, but also can improve the reliability of smoke control system. When building or defense project of public entertainment set mechanical smoke extraction facilities, if the fire smoke exhaust system combined with the ventilation system unified consideration ventilation duct and fire smoke exhaust duct into one, you must ensure that air duct fire performance conforms to exhaust duct requirements and also have the ability to assume the exhaust volume, so that the design-time ventilation and air conditioning systems should be in accordance with the requirements of the exhaust system to design.

First, the fan for use. From system view, the fan can be divided into sections for both the use and the use of both forms, some use either form of duct or main duct is shared, the fan is set individually. In case of fire, ventilation and air conditioning system automatically switches to the exhaust fan. All use forms not only wind road use, fan also use, but you need to solve the problem of air flow are inconsistent, while exhaust system partition should not be cross fire.

Second, the exhaust of air volume and air pressure. Both systems, the two operating segments of the pipeline of the air flow is different, because both fans of wind pressure is small, making the air drop when you smoke, smoke extraction cannot be good. When different exhaust smoke partitions, the same segment of the air flow is changing, in theory, should address each smoke partition to calculate corresponding loop resistance to one of the biggest loop resistance as the basis for selected fan.

At the same time, the fan must select exhaust and smoke mix design, according to the actual situation and exhaust shaft through the duct access shaft smoke (wind). The wind pipes as a common use of ventilation and smoke extraction, exhaust fan and exhaust air operation, as the exhaust ventilation system, fire, fire protection control center switches to fire smoke, smoke removal time.

To sum up the fire smoke damage on officials is very large, public entertainment ' own problems, smoke is elimination of flue gas. Smoke mainly will fire when the large amounts of smoke to be ruled out in a timely manner, and to prevent smoke from the burning area to non-fire district spread, particularly to prevent flue gas intrusion as evacuation channels of corridor, staircase and vestibule, ensuring a safe and unimpeded evacuation routes and evacuation.