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Smoke prevention system in the design of smoke prevention and exhaust design by the wholesale manufacturer of phenolic board of single sided color steel

Source:http://www.cdhbjn.com/news/741.html       Begintime:2018-04-13

Plastic steel plate wholesale manufacturers introduced phenolic anti smoke exhaust design in the system

1, the pressure calculation method of air volume

Firstly, the pressure difference method: when the evacuation channel when the door is closed, the pressure value of the pressure is kept.

Ly=0.827xAx P1/nx1.25x3600 0.827-- air leakage coefficient

A is the door gap leakage calculation of total area (M2) in accordance with the door width of 0.002~0.004m

The pressure difference on the two sides of the crack of the delta P-- (Pa) for smoke proof staircase 40~50Pa, room fire elevator room 25~30Pa 1.25 common antechamber imprecision of additional coefficient

The n-- index (generally 2)

The wind speed method: open the fire floor evacuation door, need to maintain relatively at certain speed to send the air

LV=nxFx V x (1+b) x3600/a

V - open the doorway of the average wind speed, 0.7~1.2 (m/s)

Open a door in the area of F-- (M2)

A-- back pressure coefficient, according to the degree of sealing pressure, air leakage rate of additional value of 0.6~1.0 b--, calculate the number of 0.1~0.2 n-- and open the door, for multi-storey buildings and building 20 floors below the 2 and 20 layer 20 layer 3 above.

The comparison of Ly, Lv and code for fire protection of pressurized air supply numerical, determine pressurized air supply.

2, pressure and difficult problems in calculation of air quantity

The common antechamber pressurizing air flow is related to the number of storeys of the building and opened the door; the n value is directly related to the open air quantity problem. The following 20 layers according to the two air calculation, level 20 and above in accordance with the three wind calculation. To check the door for the standard wind section. In the fire control should also be in accordance with the requirements of implementation.

Example: when building less than 20 layers, the common antechamber pressurizing air flow is 12000~16000m3/h, the room door size is 1.2 x 2.1, two layer open air outlet, the critical air velocity is 0.66~0.88m/s, and meet the requirement of the wind speed. Open the three layer air outlet openings the wind speed 0.441~0.59m/s, does not meet the requirements of the wind.

Second, the room has two or more than two people, according to the numerical calculation of air volume multiplied by the 1.5~1.75 determined to open the door, through the door of the wind speed should not be less than 0.7m/s. Here is the door does not include smoke proof staircase to the front door. Smoke proof staircase is greater than the pressure of the pressure chamber.

Smoke stair pressurization, the problem of preventing underground

In multi-storey buildings, if only a layer of underground stair, n 1, V at the door by wind speed should be appropriately increased, should be 0.9~1.2m/s. To calculate the value of direct access and comparison.

LV=nxFx V x (1+b) x3600/a

=1x1.6x2.0x0.9x1.1x3600/0.8

=14256m3/h

Other basement pressurization can be implemented according to this method.

Fourth, on the part of the smoke proof staircase and common antechamber adopt natural ventilation, the underground part of smoke preventing staircase and combined atria need mechanical ventilation situation?

Analysis: underground stairwell pressurization and common antechamber respectively. (in accordance with the building regulations implementation)

Fifth, on the part of the common antechamber mechanical ventilation, underground air combined atria calculated?

Analysis: share system. The reason is the control system can realize the fire smoke control layer and the upper layer; and consider a point.

The pressure and overpressure of the blast system

A, set the pressure relief valve, and set the fire valve in 70 DEG C through the firewall, vent opening area formula plate:

F= (LV-LY) /3600x6.41 F- vent opening area pressure valve plate (M2)

LV- pressurized air supply (m3/h)

LY- when the evacuation channel when the door is closed, the pressure parts to maintain a certain pressure value is required air volume (m3/h)

B, with a bypass valve, in the staircase and antechamber combined atria proper position of a pressure sensor, control pressure blower outlet bypass relief valve, adjust the pressure value.

3, other provisions

1, 4.5.5-3: mechanical outlet should not be greater than 7m/s, the exhaust port is less than 10m/s, public gathering places should not be greater than 5m/s, the natural air outlet should not be greater than 3m/s.

Second, mechanical ventilation and mechanical exhaust ventilation pipe for pipeline should not cross fire or other fire hazard in a large room, when to travel through time, should be arranged through the fire valve, pressurization pipeline fire valve temperature is 70 DEG C, air supply pipeline fire valve temperature is 280 DEG C

Understand: in the air velocity is large, even if the ambient temperature is high, the temperature in the air could not reach 70 DEG C; air supplement (industrial plant) can also fill the air more than 70 DEG C. Air supply pipeline fire valve temperature can be 70 degrees or 280 degrees celsius.

Third, 4.9.3-2: total area by anti smoke stair every 5 layers can be opened outside the window and wall should not be less than 2 square meters, and the top open area of not less than 0.8 square meters.

Fourth, 4.10.11: failed to set in a separate pipeline well the pressurized air supply pipe should be fire air using the fire resistance limit is not less than 1.0h tube. Note: when the pressurized air supply pipe is made of steel, should adopt the appropriate thickness of the steel plate or the thickened fireproof plate coating and other measures, in order to meet the requirements of the fire resistance limit is not less than 1.0h.

Question: how much is the exhaust pipe of the fireproof limit?

Answer: the experience of 1.2mm thick steel plate fire for 1 hours.

2mm thick steel plate fire for 1.5 hours.

The technical measures of 4.10.9-10 in smoke proof staircase outlet can be used since the vertical louver type or normally open shutter tuyere, and backflow prevention device or electric control valve is arranged in the pressurizing fan out section.

Question: since the vertical louver type air pressure fan in press section should also be combined with reflux device.

The reason: since the vertical louver due to light weight, in the case of a small wind is blown open, so to recycle in the pressurization fan section extrusion device.

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