11. Calculate Size of Staircase Pressurization Fan for Highrise Building
CALCULATE SIZE OF STAIRCASE PRESSURIZATION FAN FOR HIGHRISE BUILDING
May 25, 2025 Leave a comment
Calculate Size of Staircase Pressurization Fan having following Details
- Building Height is 49 Meter * No of Staircase Door is 14 No’s * No of Fire Escape Door is 1 No at ground Floor * Staircase Door is 0.9 meter width and 2 meter height * Door is single Leaf and opening at Staircase (Pressurization) Side * Air Velocity across door is 0.75 m/sec
CALCULATION:
(1) AIR VOLUME REQUIRED WHEN ALL DOORS ARE CLOSED:
- Design Pressure differential Level as per building height is as under
Pressure Level
Building Height (meter)
Fire Pressure (Pa)
Wind Stack Effect (Pa)
Design Pressure (Pa)
0
8.5
8
25
5
8.5
8
25
25
8.5
10.5
25
50
8.5
13
50
100
8.5
19.5
50
150
8.5
29.5
50
- Air volume required when all doors are closed (Q1) = 0.827 x AE x P(1/n) * Where AE = Leakage Area from the space (m2) * P =Pressure Differential * n=Leakage Factor * As per above Table considering Air Pressure differential (P) = 50 Pa * As per following Table Single Leaf Doors in Frame Opening into Pressurized Space =0.01 m2
Type of Door
Leakage Area (m2)
Single Leaf Doors in Frame Opening into Pressurized Space
0.01
Single Leaf Doors in Frame Opening Outwards
0.02
Double Leaf Doors with or without Central Rebate
0.03
Lift Door
0.06
- Here No of Staircase Door are 14 No’s * AE=Total Leakage Area = 0.01 x14 = 0.14 No’s * n=Leakage factor for Door is 2 as per following Table
Leakage Factor
n
Leakages area like Door
2
Leakages small area like window crack
1.6
- Air volume required when all doors are closed (Q1) = 0.827 x AE x P(1/n) * Air volume required when all doors are closed (Q1) = 0.827 x 0.14x 50(1/2) * Air volume required when all doors are closed (Q1) =0.82 m3 / sec * It is assumed that there is other leakage, which are not calculated above is 50%. * Air volume required when all doors are closed (Q1) =0.82 X50% * Air volume required when all doors are closed (Q1) =1.23 m3/sec
(2) AIR VOLUME REQUIRED WHEN DOORS ARE OPENED:
- Area of Staircase Door = Length x width = 2 x 0.9 * Area of Staircase Door (A)= 1.8 m2 * Air Velocity across door (V) is 0.75 m/s =148 fpm * It is assumed that Minimum Number of Opened Doors =Escape Door + 10% of remaining Doors. * Minimum Number of Opened Doors = 1 + (14×10%) = 1+2 * Opened Door Area = Escape Door Area + 50% of Remanning Door area * Opened Door Area = (1×1.8) + ((2×1.8) x50%) =1.8 +1.8 =3.6 m2 * Opened Door Area (A) =3.6 m2 * Air volume required when doors are opened (Q2) = A x V * Air volume required when doors are opened (Q2) = 3.6 x 0.75 * Air volume required when doors are opened (Q2) = 2.7 m3/sec
(3) TOTAL AIR SUPPLIED BY THE FAN:
- Total Air Supplied = Air volume when doors are Closed+ Air volume when doors are opened * Total Air Supplied =Q1+Q2 * Total Air Supplied = 1.23 + 2.7 m3/sec * Total Air Supplied = 3.93 m3/sec * Total Air Supplied = 3.93 x 2113 * Total Air Supplied = 8300 CFM * Total Air Supplied per Floor = 8300/ 14 = 593 CFM
CONCLUSION:
- Capacity of Staircase Pressurization Fan = 8300 CFM