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Updated: Nov 24


Ducted system is connected to Fan Coil Units, Air Handling Units & Fresh Air handling units for distribution of air. Units are selected depending on Air volume and ESP (External Static Pressure). Let us discuss few cases of duct arrangement and application.


Duct Sizing: Fan Coil Units

Air Flow: up to 2000 CFM

Eternal Static Pressure: < 60 Pa.


FCU - Bed Room / Hotel Room - Refer Fig : 1

Where there shall be minimal Space for duct work. In such case we need to follow the grille size as duct size.


Figure : 1 Figure : 2


FCU - Bed Room / Living Room - Refer Fig : 2

Where we have enough length to install mouth piece, straight length, elbow and taper piece for supply air grille.


Straight Duct

Velocity Up to 800FPM

Friction Drop < 0.08 in. WC/100Ft


Taper for Grille

Same Size as Supply Air Grille.


FCU - Office Rooms - Refer Fig : 3

Where we have enough length to distribute the duct across the room.

Figure - 3

Main Duct

Velocity Up to 1000FPM

Friction Drop < 0.08 in. WC/100Ft


Branch Duct

Velocity Up to 700FPM

Friction Drop < 0.08 in. WC/100Ft


Dropper (Diffuser) / Shoe Collar (Grille)

Same as Diffuser, Griller size.

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โ€‹Duct Sizing: Air Handling Units Air Flow: > 2000 CFM Open Offices Main Duct Velocity Up to 1200FPM Friction Drop < 0.08 in. WC/100Ft Branch Duct Velocity Up to 800FPM Friction Drop < 0.08 in. WC/100Ft Sub Branch Duct Velocity Up to 600FPM Friction Drop < 0.08 in. WC/100Ft Dropper (Diffuser) / Shoe Collar (Griller) Same as Diffuser, Griller size.

โ€‹Duct Sizing: Fresh Air Handling Units Building / Towers Riser Duct Velocity Up to 1500FPM Friction Drop < 0.1 in. WC/100Ft Floor Entry Duct Velocity Up to 1200FPM Friction Drop < 0.08 in. WC/100Ft Branch Duct Velocity Up to 800FPM Friction Drop < 0.08 in. WC/100Ft Sub Branch Duct Velocity Up to 600FPM Friction Drop < 0.08 in. WC/100Ft Fresh Air Discharge Velocity Up to 400FPM Friction Drop < 0.08 in. WC/100Ft Bell Mouth with wire mesh.

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Duct Material

Space

โ€‹Application

Duct Material

Hotel, Shopping Mall, Commercial, Residential - Rooms, Flats, Offices, Shops, Corridors

Supply Air, Return Air, Fresh Air, Toilet Extract

G.I, P.I

Ware House, Super Markets, Show rooms

Supply Air

G.I, P.I & Fabric Duct

Hotel, Office, Residential - Riser / Shafts

Fresh Air, Toilet Extract, Kitchen Extract

G.I

Residential - Kitchen

Kitchen Extract

G.I

Restaurant & Commercial Kitchen

Kitchen Extract

Fire Rated Duct

Fire & Safety Services

Staircase & Lift Well Pressurization, Corridor Smoke Extract & Make up, Car park Extract & Make up.

Fire Rated Duct

At BTU Electromechanical Works LLC, Dubai, UAE, we execute HVAC Design & Build projects ranging 250 TR to 660 TR such as 5 Star Hotels, Logistics Centers, Community Malls. Also we provide technical support such as Heat Load, Duct Sizing, Pipe Sizing, ESP Calculation, Pump Head Calculation and Complete HVAC System Design, to equipment suppliers, MEP Contractors and Clients. We can be reached at projects@btullc.com, www.btullc.com.


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