Calculate Size of Lift Pressurization Fan for Highrise Building

Calculate Size Lift Well Pressurization Fan having following Details

• Type of Building is Commercial and Sprinkler Protected
• Number of Lift Door (Basement to Terrace) is 17 Nos (B+G+15)
• Lift Shaft width is 3600mm and Length is 3600mm
• Lift Shaft height is 45 Meter
• Vent window Size at Top of Lift Shaft is 320mm to 320mm
• Lift Door width is 1 meter and Height is 1.2 meter.
• No of Lift Door is 17 Nos
• No of Floor door (Single Leaf) is 26 Nos
• Air Velocity across door is 0.75 m/sec

Calculation:

• Air Leakage are calculated on following areas

1. Leakages through Door on each Floor
2. Leakages through lift Doors, Shafts, Vents
3. Leakages through External Wall, Floors
4. Open Lift Door

(1) Leakages through Door on each Floor

• No of Floor door (Single Leaf) is 26 Nos
• Leakage Area around the Door as per BS:5588 = 0.01m2

Air Leakage Data for Doors (BS 5588: Part-4)
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

• Total leakage area all doors on all floors (A1): No of Door x Leakage area around Door
• Total leakage area all doors on all floors (A1):26 x 0.01
• Total leakage area all doors on all floors (A1):0.26 m2

(2) Leakages through lift Doors, Shafts, Vents

(a) Leakage through Lift Shaft:

• Lift Shaft Wall Perimeter = 2 x (Lift Shaft Width + Lift Shaft Length)
• Lift Shaft Wall Perimeter =2 x (3.6+3.6)
• Lift Shaft Wall Perimeter =14.4 Meter
• Leakage Area through Lift Shaft = Lift Shaft Perimeter x Lift Shaft Height
• Leakage Area through Lift Shaft =14.4 x 45
• Leakage Area through Lift Shaft =648.8 Meter
• Leakage Area Ratio for Lift Shaft: (A/Aw) =0.00084 as per NFPA 92A

Typical Leakage Area for Walls & Floors for Commercial Buildings (NFPA-92A)
Construction	Wall Tightness	Area Ratio
Exterior Building Wall (Including Construction Cracks but not around window & doors)	Tight	0.00005
	Average	0.00017
	Loose	0.00035
	Very Loose	0.0012
Staircase Wall (Including Construction Cracks but not around window & doors)	Tight	0.000014
	Average	0.00011
	Loose	0.00035
Lift Shaft Wall (Including Construction Cracks but not around window & doors)	Tight	0.00018
	Average	0.00084
	Loose	0.0018
Floor (Including Construction Cracks but not around window & doors)	Tight	0.0000066
	Average	0.000052
	Loose	0.00017

• Effective leakage Area (a)= Leakage Area Ratio for Lift Shaft x Leakage Area through Lift Shaft.
• Effective leakage Area (a)= 0.00084 x 648.8
• Effective leakage Area (a)=0.544 m2

(b) Leakages through Lift doors

• No of Lift Door =17 Nos
• Leakage Area around the Lift Door as per BS:5588 = 0.06m2
• Leakage area around lift doors (b): No of Lift Door x Leakage around Lift Door
• Leakage area around lift doors (b): 17 x 0.06
• Leakage area around lift doors (b): 1.020 m2

(c) Leakage through Vent at the head of the shaft

• Vent Window Area (At the head of the shaft)(c) = Vent window width x Vent window height
• Vent Window Area (At the head of the shaft) (c) = 0.320 x 0.320
• Vent Window Area (At the head of the shaft) (c) =0.102
• Total Leakage Area (A2) = (a)+(b)+(c)
• Total Leakage Area (A2) = 0.544+1.020+0.102
• Total Leakage Area(A2) =1.667 m2
• Effective Leakage Area (Ae)= A1 x A2 / (A12 + A22)0.5
• Effective Leakage Area (Ae)= 0.26 x 1.667 / (0.26 + 1.667) 0.5
• Effective Leakage Area (Ae)= 0.257 m2

(4) Open Lift Doors

• No of Open Lift Door = 2 Nos
• Lift Door Area = Lift Door Width x Lift Door Height
• Lift Door Area = 1.0 x 1.2
• Lift Door Area =2.2 m2
• Open Lift Door Area = No of Open Lift Door x Lift Door Area
• Open Lift Door Area = 2 x 2.2
• Open Lift Door Area = 4.4 m2
• Velocity through Open Door = 0.75 meter/sec (*As per BS 5588: Part-4)
• Air Flow through open doors = Air Velocity x Open Lift Door Area
• Air Flow through open doors = 0.75 x 4.4
• Air Flow through open doors =3.3 m3/sec

Calculate Air Flow for Lift well Pressurization

• Air Flow for Lift Well Pressurization = 0.839 x Ae x (ΔP)1/2
• Minimum Design Pressure difference for Lift well pressurization (ΔP) = 50pa (*As per BS 5588)
• Minimum Design Pressure difference for Lift well pressurization (ΔP) = 50pa (*As per NBC 2016)
• Minimum Design Pressure difference for Lift well pressurization (ΔP) = 10pa (*As per NFPA 92A)
• Consider Design Pressure difference for Lift well pressurization (ΔP) = 50pa

The pressure difference AS per NBC-2016 (Clause 4.4.2.5)
Enclosed Lobbies (or corridors)	25 to 30 Pa
Lift Shaft	50 Pa
Staircases	50 Pa
Enclosed staircase adjacent to such lobby (or corridors)	50 Pa
Enclosed staircases adjacent to non-pressurized lobby (or corridors)	50 Pa

Minimum Design Pressure difference (BS 5588: Part-4)
Type	Building	Air Flow through Door way	Minimum Design Pressure difference
A	Residential or Sheltered House or Building having Three Door Protection	0.75 Meter/Sec	50 Pa
B	Protection of Fire Shaft	2.00 Meter/Sec	50 Pa
C	Commercial Premises	0.75 Meter/Sec	50 Pa
D	Hotels or Institutional Type Building	0.75 Meter/Sec	10 Pa

 

Minimum Design Pressure difference (NFPA-92A, Table:4.4.2.1.1)
Type of Building	Ceiling Height	Minimum Design Pressure difference
Sprinklered	Any	12.5 Pa
Non Sprinklered	2.75 Meter	25.0 Pa
Non Sprinklered	4.58 Meter	35.0 Pa
Non Sprinklered	6.41 Meter	45.0 Pa

•  Air Flow for Lift Well Pressurization = 0.839 x 0.257 x (50)1/2
• Air Flow for Lift Well Pressurization = 1.508 m3/sec
• Total Air Flow for Lift Well Pressurization = Air Flow for Lift Well Pressurization+ Air Flow through open doors
• Total Air Flow for Lift Well Pressurization = 1.508 + 3.3
• Total Air Flow for Lift Well Pressurization = 4.8 m3/sec
• Consider Safety Factor =10 %
• Total Air Flow for Lift Well Pressurization = 4.8 x 1.1
• Total Air Flow for Lift Well Pressurization =5.288 m3/Sec
• Total Air Flow for Lift Well Pressurization =5.288 x 2118.88
• Total Air Flow for Lift Well Pressurization =11206 CFM

Conclusion:

• Capacity of Lift Well Pressurization Fan = 11206 CFM

Quick Reference-Lift / Service Duct / HVAC / Sub Station

 

LIFTS
Model Building-Bye-laws-2016, Ministry of Urban Development, Government of India
Head	Clause	Description
LIFTS	7.10.a	Provision of the lifts shall be made for all multi- storied building having a height of 15.0 m. and above.
	7.10. b	Grounding switch at ground floor level to enable the fire service to ground the lift car in case of emergency shall also be provided.
	7.10.c	The lift machine room shall be separate and no other machinery be installed in it.
Lift Enclosure	7.10.1.a	Walls of lift enclosures shall have a fire rating of two hours. Lift shafts shall have a vent at the top of area not less than 0.2 sq m.
	7.10.1.c	Landing door in lift enclosures shall have a fire resistance of not less than one hour.
	7.10.1.d	The number of lifts in one lift bank shall not exceed four. A wall of two hours fire rating shall separate individual shafts in a bank.
	7.10.1.e	Lift car door shall have a fire resistance rating of 1 hour.
	7.10.1.f	For buildings 15.0 m. and above in height, collapsible gates shall not be permitted for lifts and solid doors with fire resistance of at least one hour shall be provided.
	7.10.1.g	If the lift shaft and lobby is in the core of the building a positive pressure between 25 and 30 pa shall be maintained in the lobby and a possible pressure of 50 pa shall be maintained in the lift shaft. The mechanism for the pressurization shall act automatically with the fire alarm/sprinkler system and it shall be possible to operate this mechanically also.
	7.10.1.h	Exit from the lift lobby, if located in the core of the building, shall be through a self-closing fire smoke check door of one-hour fire resistance.
	7.10.1.i	Lift shall not normally communicate with the basement. If however, lifts are in communication, the lift lobby of the basement shall be pressurized
	7.10.1.k	Telephone/talk back communication facilities may be provided in lift cars for communication system and lifts shall be connected to the fire control room of the building.
	7.10.1.l	Suitable arrangements such as providing slope in the floor of the lift lobby shall be made to prevent water used during fire fighting, etc at any landing from entering the lift shafts.
	7.10.1.m	A sign shall be posted and maintained on every floor at or near the lift indicating that in case of fire, occupants shall use the stairs unless instructed otherwise. The sign shall also contain a plan for each floor showing the location of the stairways. Floor marking shall be done at each floor on the wall in front of the lift-landing door.
	7.10.1.n	Alternate power supply shall be provided in all the lifts.
Fire Lift	7.10.2.b	The lift shall have a floor area of not less than 1.4 sq.mt. It shall have a loading capacity of not less than 545 kg. (8 persons lift) with automatic closing doors
	7.10.2.c	The electric supply shall be on a separate service from electric supply mains in a building and the cables run in a route safe from fire, that is within a lift shaft. Lights and fans in the elevator having wooden paneling or sheet steel construction shall be operated on 24-volt supply.
	7.10.2.d	In case of failure of normal electric supply, it shall automatically switchover to the alternate supply. For apartment houses, this changeover of supply could be done through manually operated changeover switch. Alternatively, the lift should be so wired that in case of power failure, it comes down at the ground level and comes to stand still with door open.
	7.10.2.f	The words ‘F1RE LIFT’ shall be conspicuously displayed in fluorescent paint on the lift landing doors at each floor level.
	7.10.2.g	The speed of the fire lift shall be such that it can reach to the top floor from ground level within one minute.

 

 

SERVICE DUCTS
Model Building-Bye-laws-2016, Ministry of Urban Development, Government of India
Head	Clause	Description
SERVICE DUCTS	7.13.a	Service duct shall be enclosed by walls and door, if any, of 2 hours fire rating. If ducts are larger than 10 sq m. the floor should seal them, but provide suitable opening for the pipes to pass through, with the gaps sealed.
	7.13.b	A vent opening at the top of the service shaft shall be provided between one-fourth and one-half of the area of the shaft
ELECTRICAL SERVICES	7.14.a	The electric distribution cables/wiring shall be laid in a separate duct shall be sealed at every floor with non-combustible material having the same fire resistance as that of the duct. Low and medium voltage wiring running in shaft and in false ceiling shall run in separate conduits.
	7.14.b	Water mains, telephone wires, inter-com lines, gas pipes or any other service lines shall not be laid in ducts for electric cables.
	7.14.c	Separate conduits for water pumps, lifts, staircases and corridor lighting and blowers for pressuring system shall be directly from the main switch panel and these circuits shall be laid in separate conduit pipes, so that fire in one circuit will not affect the others. Master switches controlling essential service circuits shall be clearly labelled.
	7.14.d	The inspection panel doors and any other opening in the shaft shall be provided with airtight fire doors having fire resistance of not less then 1 hour.
	7.14.e	Medium and low voltage wiring running in shafts, and within false ceiling shall run in metal conduits. Any 230 voltage wiring for lighting or other services, above false ceiling should have 660V grade insulation. The false ceiling including all fixtures used for its suspension shall be of non-combustible material.
	7.14.f	An independent and well-ventilated service room shall be provided on the ground floor with direct access from outside or from the corridor for the purpose of termination of electrical supply from the licenses service and alternative supply cables. The doors provided for the service room shall have fire resistance of not less than 1 hour
STAIRCASE AND CORRIDOR LIGHTS	7.15	The staircase and corridor lighting shall be on separate circuits and shall be independently connected so that it could be operated by one switch installation on the ground floor easily accessible to fire fighting staff at any time irrespective of the position of the individual control of the light points, if any.
	7.15.a	Staircase and corridor lighting shall also be connected to alternate source of power supply.
	7.15.b	Emergency lights shall be provided in the staircase and corridor.

 

 

AIR-CONDITIONING
Model Building-Bye-laws-2016, Ministry of Urban Development, Government of India
Head	Clause	Description
AIR-CONDITIONING	7.16.b	Air -Conditioning systems circulating air to more than one floor area should be provided with dampers designed to close automatically in case of fire and thereby prevent spread of fire or smoke. Such a system should also be provided with automatic controls to stop fans in case of fire,
	7.16.c	Air- conditioning system serving large places of assembly (over one thousand persons), large departmental stores, or hostels with over 100 rooms in a single block should be provided with effective means for preventing circulation of smoke through the system in the case of fire in air filters or from other sources drawn into the system even though there is insufficient heat to actuate heat smoke sensitive devices controlling fans or dampers. Such means shall consist of approved effective smoke sensitive controls.
	7.16.1.a	Escape routes like staircase, common corridors, lift lobbies; etc should not be used as return air passage.
	7.16.1.b	The ducting should be constructed of metal in accordance with BIS 655:1963
	7.16.1.c	c) Wherever the ducts pass through fire walls or floor, the opening around the ducts should be sealed with fire resisting material of same rating as of walls / floors.
	7.16.1.d	d) Metallic ducts should be used even for the return air instead of space above the false ceiling.
	7.16.1.e	e) The material used for insulating the duct system (inside or outside) should be of flame resistant (IS 4355: 1977) and non- conductor of heat.
	7.16.1.f	Area more than 750 sq m. on individual floor should be segregated by a firewall and automatic fire dampers for isolation should be provided.
	7.16.1.h	In case of buildings more than 24 m. in height, in non-ventilated lobbies, corridors, smoke extraction shaft should be provided.

 

 

SAFETY MEASURES IN ELECTRIC SUB-STATION
Model Building-Bye-laws-2016, Ministry of Urban Development, Government of India
Head	Clause	Description
SAFETY MEASURES IN ELECTRIC SUB-STATION	7.19.1	Clear independent approach to the sub-station from outside the building shall be made available round the clock
	7.19.2	The approaches/corridors to the sub-station area shall be kept clear for movement of men and material at all times.
	7.19.5	Cable trenches of 0.6 m. X 0.6 m. dummy floor of 0.6 mt. depth shall be provided to facilitate laying of cable inside the building for connecting to the equipment.
	7.19.6	Steel shutters of 8’X 8’ with suitable grills shall be provided for transformers and sub-station room.
	7.19.7	The floor of the sub-station should be capable of carrying 10 tons of transformer weight on wheels.
	7.19.9	Sub-station space should be clear from any water, sewer, air conditioning, and gas pipe or telephone services. No other service should pass through the sub station space or the cable trenches.
	7.19.10	Proper ramp with suitable slope may be provided for loading and unloading of the equipment and proper approach will be provided.
	7.19.11	RCC pipes at suitable places as required will be provided for the cable entries to the sub station space and making suitable arrangement for non-ingress of water through these pipes
	7.19.14	Adequate arrangement for fixing chain pulley block above the fixing be available for load of 15 tons.
	7.19.16	Arrangement should be made for the provision of fire retardent cables so as to avoid chances of spread of fire in the sub-station building.
	7.19.17	Sufficient pumping arrangement should exist for pumping the water out, in case of fire so as to ensure minimum loss to the switchgear and transformer.
	7.19.18	No combustible material should be stacked inside the substation premises or in the vicinity to avoid chances of fire.
	7.19.19	The sub-station must not be located below the 1st basement and above the ground floor.
	7.19.21	The sub station space should be totally segregated from the other areas of the basement by fire resisting wall. The ramp should have a slope of 1 : 10 with entry from ground level. The entire Sub-station space including the entrance at ground floor be handed over to the licensee of electricity free of cost and rent.
	7.19.22	The sub-station area shall have a clear height of 12 feet (3.65 m.) below beams. Further the Sub-station area will have level above the rest of basement level by 2 feet.
	7.19.23	It is to be ensured that the Sub-station area is free of seepage / leakage of water.
	7.19.26	The Sub-station should be located on periphery /sub basement and (not above ground floor).
	7.19.27	Additional exit shall be provided if travel distance from farthest corner to ramp is more than l5 m.
	7.19.28	Perfect independent vent system 30 air changes per hour linked with detection as well as automatic high velocity water spray system shall be provided.
	7.19.29	All the transformers shall be protected with high velocity water spray system / Nitrogen Injection System Carbon Dioxide total flooding system in case of oil filled transformer. In addition to this, manual control of auto high velocity spray system for individual transformers shall be located outside the building at ground floor.
	7.19.34	Cable trenches shall be filled with sand
	7.19.35	Party walls shall be provided between two transformers as per the rules.
	7.19.36	Electric control panels shall be segregated.
	7.19.37	Exits from basement electric substation shall have self-closing fire smoke check doors of 2-hours fire rating near entry to ramp.

Calculate Size of Anchor Fastener for Cable Tray Support.

Calculate Size of Anchor fastener for Cable Tray Support having following Details

• CABLE TRAY DETAIL:
• Size of Cable Tray=600mm Ladder Type Cable Tray
• Weight of Cable Tray=120 kg/meter
• CABLE DETAILS (LAID IN CABLE TRAY)
• Size of Cable =3.5Cx300 Sq.mm, Alu, XLPE, Armored Cable
• No of Cable / Cable tray= 6 No’s
• Weight of Cable = 5.9 Kg/meter
• Size of Cable =3.5Cx150 Sq.mm, Alu, XLPE, Armored Cable
• No of Cable / Cable tray= 2 No’s
• Weight of Cable = 4.5 Kg/meter.
• CABLE TRAY SUPPORT DETAILS
• Cable Tray Support installed at 1 Meter of Cable Tray
• Weight of Cable Tray Support =5.8 Kg/meter
• Safety Factor=5

CALCULATIONS

• Weight of Cable Tray Support = No of Support X Weight of Support
• Weight of Cable Tray Support =1×5.8 Kg/Meter
• Weight of Cable Tray Support =5.8 Kg/Meter———(A)
• Weight of Cable Tray = No of Cable Tray X Weight of Tray
• Weight of Cable Tray =1×120
• Weight of Cable Tray =120 Kg/Meter———(B)
• Weight of 3.5Cx300 Sq.mm Cable = No of Cable X Weight of Cable
• Weight of 3.5Cx300 Sq.mm Cable =6×5.9
• Weight of 3.5Cx300 Sq.mm Cable =35.4 Kg/Meter———(C1)
• Weight of 3.5Cx150 Sq.mm Cable = No of Cable X Weight of Cable
• Weight of 3.5Cx150 Sq.mm Cable =2×4.5
• Weight of 3.5Cx150 Sq.mm Cable =9 Kg/Meter———(C2)
• Total Weight =Safety Factor X (Weight of Cable Tray support + Weight of Cable Tray + Weight of Cables)
• Total Weight =5X (5.8+120+35.4+9) Kg/Meter
• Total Weight=851 Kg/Meter—————–(1)
• Consider 4 No of 10mm size of Anchor Fastener having Basic Tensile Load Capacity of 5KN at each Support.
• Total Tensile Load= No of Anchor Fastener X 101.97XAnchor Tensile Load Capacity (KN)
• Total Tensile Load=4×101.97×5
• Total Tensile Load=1876 Kg/Meter————(2)

Here Total Tensile Load Capacity of Anchor Fastener (1876 Kg/Meter) > Total Weight (851 Kg/Meter) hence Size of Anchor Fastener is OK