What you need to know about Exhaust Hood and Ventilation System for Restaurants
Kitchen Ventilation Concepts
On top of complying to the fire, health and building codes, it is important to put together a professional exhaust hood and ventilation system for your commercial kitchen, in order to create a clean and vital environment for your staffs. Commercial cooking generate intensive grease laden air and pollutants. It takes an adquately designed system to maintain a good air flow and an odorless environment. Each system needs to be carefully designed with engineer calculations, because it has to do with static pressure and air flow, air resistane, air volumn, and other inputs such as: the total btu generated by the cooking equipments, the type of cooking equipment (char broilers and fryers generate more smoke ), the number of bends in the duct work (which impacts the static pressure), the length of the hood and the length of the duct. Any missing information will cause the end result of not passing the health and fire codes. When your architects submit plans to the health department, a hood calculation sheet is required and the following formula must be resolved:
Q = ____ A * ( ___ * ___ ) size of hood ___ sf = ___ cfm
What is a complete ventilation system composed of?
The complete ventilation system is composed of the exhaust hood system and the make-up air system. The exhaust hood system removes grease laden vapor and smoke from indoor while the make up air system provides an approximate equal amount of fresh air into the kitchen. Most health deparment require that a certain amount of fresh outdoor air to be part of the replacement air calculation to assist in indoor air quality requirement. Together the two systems form a comprehensive and balanced system that satisfies local building, health, and fire regulations.
What does a complete exhaust hood system consist of?
A complete exhaust hood system consists of three components: Type I hood (with integral grease filtration), ductwork, and the fan which is installed on the roof. (Note: A fire suppression system is also required, which is usually installed under the hood and above each piece of cooking equipment. However, it requires a different profession to design and install the fire suppression system. Please refer to a different article about this system).
What does it take to fabricate an efficient and structural sounded ventilation system?
The Kitchen Ventilation Team
The safety and design requirements of both commercial kitchen exhaust and make-up air systems require that a group of key players have sufficient knowledge of the subject to coordinate the entire process from design to operation. The following overview provides a brief description of each team member with a vested interest in the process and suggests criteria necessary to design and install a comprehensive and balanced system that offers efficient operating costs, climatic controls, and satisfies building and fire regulations.
Owner/Facility Manager
An owner/facility manager needs to understand the interdependence of each piece of the kitchen system to recognize the value of having a complete and properly integrated system that will provide a productive and comfortable work environment that is also cost effective.
Architect
The architect is responsible for the commercial restaurant’s design including fire-resistive walls, floor-to-ceiling assemblies, roof-ceiling assemblies, and the protection of openings as well as the horizontal and vertical smoke barriers. In consideration for fire protection, the architects first must determine the overall function of the structure and the type of occupancy of its spaces. The architect is also responsible to design appropriate spaces within the building that are required to be separated by fire-resistive assemblies with protected openings, as set forth in the local building code. The architect will communicate and cooperate with the authority having jurisdiction at the building site and comply with any special conditions of fire protection design required by that authority.
Contractors
Contractors must have access to and be able to use manuals and design procedures in order to fully comply with design objectives and specifications established by the kitchen ventilation system designer. SMACNA’s Kitchen Ventilation Systems & Food Service Equipment Guidelines documents industry-accepted practices for the fabrication and installation of food service-related equipment.
Code Officials
Local code authorities must be capable of judging adequacy and comparability in the installation of commercial kitchen ventilation systems and its components and assemblies. The most critical aspects of a code official’s job are fire and safety issues. However, understanding the “standards of practice” that quality contractors strive to achieve is also important.
Engineer/System Designer
The engineer or system designer is responsible for knowing where ducts, pipes, and other conduits pass through required fire-rated separations or smoke barriers. Duct penetrations must be shown on the mechanical plans and designed with an appropriate protection method. Use of standard symbols is highly recommended. International Mechanical Code (IMC) and the National Fire Protection Association Standard # 96 Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations (NFPA #96), NFPA 17A and 90A, all state that the designer must show on the plans the location and mounting details of all automatic fire doors, dampers, access panels, and other fire protection means incorporated into both the exhaust and supply systems.
To coordinate all requirements, designers must possess all necessary information on barrier locations, occupancy assignments, protection planning, rating, and identification of compartments and structural components. Drawings must show fire and smoke dampers and heat stops. The engineer/designer should specify the hourly rating and type of damper and requirements for access doors. Specific framing requirements of openings should be provided in the architectural and structural drawings submitted for building permits. Thickness and type of fire resistive material may vary by jurisdiction. There should be coordination in advance with local authorities to verify the acceptance of the methods and equipment proposed for use.
Relevant Codes and Standards
Local codes are generally adopted from either the International Mechanical Code (IMC) or the National Fire Protection Association Standard # 96 Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations (NFPA #96) or a combination of the two with particular local issues of concern included. In many major cities, local codes are written and published by local building officials; however, such codes are frequently based on one of the national codes previously mentioned.
Certain government agencies such as the General Services Administration (GSA); the Department of Health and Human Services (HHS); Housing and Urban Development (HUD); and the U.S. Army Corps of Engineers have specific standards or codes that must be accommodated in construction performed for these agencies.
In some instances, the insurance companies that underwrite the building have recommendations or standards from the American Insurance Association (AIA).
Planners and designers need to identify and consult the local authority having jurisdiction and local governing codes prior to designing a kitchen ventilation system. Consideration must be given to both the building and fire codes.
