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Commercial Kitchen hood Ventilation: Enhancing Safety and Efficiency

Updated: Dec 20, 2023


kitchen

Commercial kitchens serve as the bustling heart of restaurants, hotels, and various food establishments, where culinary creativity meets the demands of a hungry clientele. Amidst the sizzle of pans and the aromatic symphony of diverse cuisines, one crucial element often goes unnoticed – the ventilation system. Commercial Kitchen Ventilation (CKV) plays a pivotal role in ensuring a safe, efficient, and compliant culinary environment.


Understanding the Significance

In the world of gastronomy, where flames flicker and ingredients transform, the release of heat and airborne elements is inevitable. This is where thermal science, particularly latent heat, intertwines with the art of cooking. Latent heat, the energy absorbed or released during a phase change without altering the temperature, plays a crucial role in the kitchen's thermal dynamics. Consider the journey of steam rising from a pot on a busy stove. As water undergoes a phase change from liquid to vapor, it absorbs latent heat, creating a mesmerizing plume. In a commercial kitchen, where various cooking processes involve phase changes, understanding and managing latent heat become integral to maintaining a comfortable and safe culinary space.


unbalanced HVAC system

Here, a visual representation illustrates how imbalances in the HVAC system can disrupt the delicate thermal equilibrium in a commercial kitchen. Whether due to inadequate ventilation, improper ductwork design, or malfunctioning equipment, these imbalances can lead to uncomfortable working conditions for kitchen staff and compromise the efficiency of the overall ventilation system.

Hood Types

In the realm of commercial kitchen ventilation, the selection of the right hood is paramount. There are two main types of commercial kitchen hoods, known as Type I and Type II hoods. These hoods are distinguished by the types of materials they filter out of the air.


Integration with Commercial Kitchen hood Ventilation

The CKV system, with its exhaust hoods, ductwork, and make-up air components, contributes not only to air quality and safety but also to managing the thermal environment. By efficiently removing hot air, grease, and odors, CKV systems help in controlling the kitchen's temperature and ensuring a comfortable working environment for chefs and staff.

Latent heat, in this context, becomes a behind-the-scenes player, as the CKV system handles the thermal consequences of cooking processes. The efficient removal of steam and heat by the ventilation system ensures that the kitchen remains a haven for culinary creativity without becoming uncomfortably hot or compromising air quality.

latent heat

Type I Hoods

Also known as grease hoods, Type I hoods are designed to remove heat, smoke, and airborne grease. These types of hoods are often found over appliances such as fryers, broilers, grills, and ovens.


Type II Hoods

Sometimes called condensate hoods, Type II hoods work to remove steam, vapor, and other moisture from the air. Some Type II hoods even remove odors. They are often found on top of coffee machines, commercial dishwashers, and certain pizza ovens. Additionally, these types of hoods often lack a grease filter, so they shouldn’t be used interchangeably with Type I hoods.



types hood


Hood categories and classifications, as defined by standards like ASHRAE Standard 154 and Underwriters Laboratories (UL), play a crucial role in ensuring the proper design, construction, and performance of these ventilation components.


Appliance Types by Duty Category

Now, let's delve into the specific appliances found in commercial kitchens and their duty categories. The following table provides an overview of appliance types based on their duty category:


Duty Category

Heat Source

Examples of Appliances

Light duty (400°F)

Electric or gas

Ovens (including standard, bake, roasting,revolving, retherm,convection, combinationconvection/ steamer, conveyor,deck or deck-style pizza, pastry)

Steam-jacketed kettles

Compartment steamers (both pressure and atmospheric)

Cheesemelters

Rethermalizers

Medium Duty (400°F)

Electric

Discrete element ranges (with or without oven)


Electric or gas

Hot-top ranges

Griddles

Double-sided griddles.

Fryers (including open deep-fat fryers, donutfryers, kettle fryers, pressure fryers)

Pasta cookers

Conveyor (pizza) ovens

Tilting skillets/braising pans

Rotisseries

Heavy Duty (600°F)

Gas

Open-burner ranges (with or without oven)


Electric or gas

Gas underfired broilers

Chain (conveyor) broilers

Wok ranges

Overfired (upright) salamander broilers

Extra Heavy Duty(700°F)


Appliances using solid fuel such as wood, charcoal,briquettes, and mesquite to provide all or part of the heat source for cooking.


classified by temp.

Understanding the duty category and heat source of each appliance is crucial for designing an effective ventilation system, ensuring that the system can handle the specific heat and emissions generated by different types of cooking equipment.


Calculation for hood type 1:


calculation for hood type 1

1- Selected type of hood (Wall-mounted or single island or double island or ...., etc. )

2- Select type of Appliance Types Duty Category. ( Light, Medium, Heavy, or extra heavy

3- select the length of the hood according to device excise under the hood with add ( 6 inches =0.5ft ) to each side ( overhang ) to contain as much as possible smoke . (add 12 inches = 1 foot for hood )

4-The required exhausted cfm thru the hood = the longest side of the hood either length(ft)х cfm per linear ft (from table 3)



typical exhaust flow rates

wall mounted hood


Example (1) :

Wall mounted hood









wall mounted hood table

Solve :










wall mounted hood


wall mounted hood table

Example (2) :

Wall mounted hood




solve wall mounted hood table

Solve:




Make-Up Air

Ventilation is the single most important factor in the design, construction, and operation of commercial kitchens without adequate ventilation, no kitchen will operate efficiently.


The areas outside the kitchen, such as waiting, dining and bar spaces, must be conditioned and ventilated while maintained slightly positively pressurized relative to the kitchen and the outdoors. Common problems caused by an unbalanced system include negative .


Kitchen supply air: is outdoor air introduced through the HVAC or ventilating apparatus, dedicated to the comfort conditioning of the space in which the hood is located. In many cases this may be an ideal source of replacement air because it also provides comfort

conditioning for the occupants.

Makeup air: is outdoor air introduced through a system dedi- cated to provide replacement air specifically for the hood. It is typ- ically delivered directly to or close to the hood. This air may or may not be conditioned. When conditioned, it may be heated only;

generally only in extreme environments will it be cooled.

Transfer air: is outdoor air, introduced through the HVAC or ven-tilating apparatus, dedicated to comfort conditioning and ventilation requirements of a space adjacent to the area in which the hood is located. The device providing transfer air must operate and supply

outdoor air whenever the hood is operating.



diffusers near hood

Do not use directional diffusers of any type in a commercial kitchen.











diffuser with side entry plenum

Perforated Return Diffuser with Side Entry Plenum









laminar flow diffuser

Laminar Flow Diffuser











fabric diffuser

Fabric Diffuser








Air balance for commercial ventilation kitchen



air balance for commerical ventilation kitchen


air balance for commerical ventilation kitchen



air balance for commerical ventilation kitchen

Conclusion

In the realm of culinary excellence, where flavor profiles and techniques reign supreme, Commercial Kitchen Ventilation emerges as a multifaceted solution. Beyond its role in air quality and safety, CKV integrates seamlessly with the thermal dynamics of the kitchen, managing latent heat and ensuring a harmonious environment for chefs to craft their culinary wonders.


Additional information :


NUMBER OF FILTERS REQUIRED:

Filter Area Needed(sq-ft ) = Volume of exhaust air (CFM) / Permissible face velocity(FPM)

Number of filters required = Filter area needed (sq-ft )/ actual fitter surface area (sq-ft )

NOTE : The optimum operating face the velocity of 300 FPM across the filter.


  • Air HEPA filters have a pressure drop approximation of between 50-200Pa, depending on the airflow, air duct, and how clogged the filter is. This can be used as a rough range to find and size a fan.




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