Kitchen-Hood Ventilation Designing

Buildings with Kitchens 

1. Hotels

2. Restaurants 

3. Hospitals

4. Canteens

5. Retail Malls

6. Residences

7. Jails etc.

Basic purpose of kitchen ventilation

•  To provide a comfortable environment in the kitchen.
•  to ensure the safety of the people working in the kitchen and other building occupants by:
• Effective removal of effluents which may  include gaseous, liquid and solid contaminants produced by the  cooking process and products of fuel and food combustion.
•  Effluents con be life threatening and flammable

Types of Hoods

1. Wall type hood

2. Island type hood

P= L+2W for wall type hood

P= 2L+2W for Island type hood

KITCHEN HOOD SYSTEM    

An exhaust hood 

• The centre piece of any kitchen ventilation system (KVS)
• Not just a sheet metal box but a critical component is a well engineered system
• Much greater awareness today about the need for an effective KVS
• Issues are health, safety, efficiency and energy savings

Exhaust Hoods

• Type 1 - for removing grease & smoke : used for cooking appliances
• Type 2 - for steam, vapour, heat & odour when grease is not present : used for diswashers, steam tables etc.

Basic styles of type 1 hood

• Wall mounted canopy 
• Single island 
• Double island 
• Back shelf or proximity
• Pass over 
• Eyebrow

Hood Styles

Wall canopy hood

• Cooking appliance placed against a wall
• Minimum air flow requirement 
• 3" builts in gap between hood & wall
• Three finished sides
• Less susceptible to cross drafts
• Minimum overhang requirement : 6" on sides and 6" - 12" in front for full captue

Single island hood

• Cooking appliance/s (row) placed in the middle ( not against all )
• Four finished sides
• More susceptible to cross drafts 
• Recommended overhang : 12" on all 4 sides
• Baffle filters in "V" configuration

Double island hood

• Double row of appliances placed back to back
• two wall canopy hoods placed back to back
• Recommended overhang : 12" on all 4 sides

Basic styes of type 2 hoods

• Oven hood
• Condensate hoods

Type 2 hood - Condensate hood

• Removal of hesat, odour and omisture
• Condensate baffle and gutter to condense moist air and drain the water
• Used over diswashers

Exhaust flow rate 

• Calculation of proper exhaust flow rate is very critical for effective operation oa a KVS
• The upward velocity o fthe effluent thermal currents is mainly a function of the temperature of the cooking surface and varies from 16FPM over steam equipment to 160 FPM over charcoal Broilers.
• Appliances categorized in 4 groups by cooking duty

Appliance duty category

• For a combination of appliances in a row under a single hood, the flow rate is based on the heaviest duty appliance unless the hood design permits different rates over different secions of the hood.

CFM = 200xP for  Heavy cooking 

CFM = 150xP for  Medium cooking 
CFM = 100xP for  Light cooking 

• Exhaust/makeup air 1500-2200 /fpm duct velocity
• Duct to be terminated 40" above the roof
• Cleanouts to be provided at the base of riser and every 20 feer
• Duct sheet metal gauge 

                                    1. 16ga. galvanized steel

                                    2. 18ga. 304 S.S

• Hood construction 18ga. minimum
• Black steel duct is used all kitchen ducts (Hood) S.Steel duct is used for laundry exhaust.
• Stainless steel

        430 for cheap & catches rust eaily

        304 for this type is used for hood

        316 & 318L for special & pure stainless steel for operation theater in hospitals.