According to Vietnamese standards: when creating the pressure difference between the emergency staircase and the outer hall must be more than 20Pa. Purpose when there is a fire incident, smoke is not allowed to gather in the escape ladder. In order to facilitate escape.
Technical requirements:
Pressurization level: When all the ladder inlets are closed, the supply air should be sufficient to maintain the following differential pressure: Designated area Pressure differential should be maintained Entire staircase 50 Pa 10%
- This system is applied to the escape ladder, the pressure generation will be done by a centrifugal fan placed on the roof. This fan will supply pressurized gas through the pressurizing gene, distributed to each floor through the wind mouth.
- The air escape velocity is 0.75 m / s when the exit door is opened simultaneously on the adjacent floor, the last two doors on the ground floor are open and all other doors of the pressure ladder are opened at all Other floors are closed.
- Door opening force is not more than 110N - All power supply and control cables must use fireproof cable.
- The power supply to the pressurized fan will be the priority.
- Each pressurized area should provide an air outlet to avoid overpressure.
- The operation of all pressurized systems will be controlled directly from the automatic fire alarm whenever there is a "fire" signal from the fire alarm center. The emergency push button to start the pressurization system is installed no more than 1m from the entrance to the staircase, outside the cage. The system cannot be stopped unless there is a manual interrupt mode.
- Each system will be provided with an on / off control switch in the main fire control cabinet.
System calculation:
Calculation conditions:
Speed when door is open (V- m / s): 0.75
Useful door area (A- m2) 1.54
Number of open doors (n) 4 Number of floors m (1 basement) - 2 doors for each floor.
Recipe: Qsdo (m3 / s) = AxVxn + 0.83 x (mx2-n) Alex Ql (m3 / s) = 0.83xAlexmx2x Qs (m3 / s) = Qlx1.5
With:
- Qsdo: wind flow when the pressure difference is 10 Pa (at the same time 2 doors open simultaneously and 2 doors on the ground floor are opened.
- Ql: calculated air flow at the differential pressure of 50 Pa (when all doors are closed)
- Qs: design air flow rate at 50 Pa difference (at all doors closed)
- Ale door slot area - 0.01m2 according to BS EN 12101-6-2005 standard
- Q: choose the pressurized flow rate (choose the maximum value between Qs and Qsdo)
