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Do you really understand the design of ventilation and exhaust pipe of underground garage?
2021-11-26       Source:尊龙凯时人生就是搏

In recent years, due to the rapid increase of urban car ownership, the design projects of underground parking garage are also increasing rapidly. The design of ventilation and smoke prevention and exhaust pipe in underground garage is also changing, especially the problem of dual use is concerned by hVAC designers.


First, the change of smoke control and smoke exhaust

1. Change of smoke prevention zone

The increase of the maximum allowable floor area of underground garage fire partition is a remarkable change. In general, for one, two level of fire rating of the building, the maximum allowable area of 2000 square meters, and if the garage is equipped with automatic fire extinguishing system, the area can be doubled, which brings an important result is a significant increase in the smoke partition area.


Because the smoke zone can not cross the fire zone, so the maximum construction area of the smoke zone can reach 2000 square meters, the increase of the area naturally reduces the number of smoke exhaust system in the garage. For example, the area of the garage is not more than 2000 square meters, now only set a smoke exhaust system can, in the design, construction, operation and management are much simpler.


2. Change of smoke emission

According to the latest specifications, the smoke exhaust volume of the smoke exhaust fan should be calculated according to the air change times of not less than 1 /6 hours, and the calculated value of the smoke exhaust volume has a significant change compared with the previous. Still take a 2000㎡ underground garage as an example, before at least four independent smoke exhaust system, assume that each system burden 500㎡ smoke partition, a system of smoke exhaust volume of 30000m3/h, if the car inventory set automatic fire extinguishing system, fire partition can be expanded to 1000㎡, at this time at least two independent smoke exhaust system.


Assuming that each system bears two smoke prevention zones of 500㎡, the smoke emission capacity of this system is 60000m3/h, and according to the new library regulations, as long as a smoke emission system is designed in this case, it can meet the requirements. Assuming that the calculated net height of the garage is 2.8m, the exhaust volume is 33600m3/h regardless of whether there is a fire extinguishing system in the garage. Thus, the more profound significance is that the designers can combine the exhaust system and smoke exhaust system of the underground garage on a basis.



Two, the traditional underground garage ventilation, smoke control and exhaust system design (ventilation and smoke exhaust system)


Traditional design methods:

1. Garage air supply system is also used as air supplement for smoke exhaust

2. Air exhaust and smoke exhaust system share equipment and air duct

3. Smoke outlet and upper air outlet should be used together

4. When exhausting air, the upper exhaust tuyere bears 1/3 air volume, and the lower exhaust tuyere bears 2/3 air volume

5. Four smoke will result in upper exhaust mouth when the wind speed is too large, in order to solve this problem, will be in the upper add a certain amount of exhaust port (normally closed), at the same time in the lower row tuyere branch pipe fortification smoke fire damper regulator, fire electric outlet close all lower branch pipe smoke fire valve regulating valve on the upper outlet exhaust port (normally closed) and smoke into the joint.


Third, the disadvantages of the traditional underground garage ventilation, smoke control and exhaust system design


And the use of a large number of electric control valve, sharp increase of engineering cost, complex control system, fire smoke fire damper regulator once failure from a lower to attract flue gas, not only can not effectively control and eliminate smoke, it will make flue gas with lower outlet suction spread to the lower space, direct threat to evacuate, Therefore, the reliability of the ventilation and smoke exhaust system as a smoke exhaust system is low.


Fourth, the traditional underground garage ventilation, smoke control and exhaust system design improvement

1. Garage air supply system is also used as air supplement for smoke exhaust


2. The exhaust system only Shared hosting and exhaust system and the supervisor section, and then a branch road, set up in a row YanZhi smoke fire damper (280 ° C, normally closed), on the exhaust branch fortification smoke fire dampers (70 ° C, normally open) fire fire control center only for these two valve opening and closing can be achieved exhaust system to the exhaust system transformation. Thus reduce the number of electric control valves, reduce the cost of the project, improve the stability of the system, compared with the traditional system, is the exhaust and exhaust each set of branch pipe. Because the distance between the smoke outlet and the farthest smoke point is not more than 30m, the smoke exhaust pipe will not be too long, and a higher flow rate can be used for smoke exhaust, and the cross-section size of the smoke exhaust pipe can be made smaller.


Five, underground garage design matters needing attention:

Because the underground garage itself is not very high noise requirements, so as far as possible to reduce the size of the air duct, in order to reduce the cost and save space.


Conclusion: Because the automobile emitting harmful substances belongs to the object in motion, and the exhaust gas containing most harmful substances is high temperature jet, the harmful gases cannot stay in the lower part of the garage stably, therefore, the daily exhaust air of the garage is discharged from the top, and all the tuyars are placed in the upper part of the garage is feasible. At the same time, a smoke exhaust fire valve that can close automatically when the temperature exceeds 280℃ is installed on the branch pipe, so that the fire exhaust air duct system and the daily exhaust air duct system can be completely integrated.


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