Calculate Size of Staircase Pressurization Fan for Highrise Building

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

• 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

• 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

• 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