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What Every Code Official Needs to Know about Building Services and Systems

Part 1: Commercial Cooking Appliances, Ventilation Systems and Cooking Oil Storage

Industrial kitchen appliances

March 5, 2021

Authored by: John K. Taecker, Senior Regulatory Engineer, and Bruce E. Johnson Regulatory Services Regional Manager *Both authors are Distinguished Members of Technical Staff - William Henry Merrill Society



An important component of achieving and maintaining building safety is the code authorities’ knowledge of building services and systems. This four-part series will focus on specific building systems where UL has received questions or have been engaged in thoughtful discussion for the shaping of testing requirements and installation concerns. Part 1 of our series focuses on an important area of many buildings the busy kitchen. In this article, we will explore important aspects of commercial cooking systems and cooking oil storage.

The safe operation of commercial cooking systems requires proper installation as well as periodic inspection, testing, maintenance and cleaning as mandated by the model codes, equipment standards and manufacturer’s instructions. These requirements are found in the International Fire Code (IFC) that reference both the International Mechanical Code (IMC) and NFPA 96, Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, and the NFPA 1 Fire Code that references to NFPA 96.

The requirements that address health, sanitation and energy efficiency for commercial cooking installations and operations are covered in other codes and standards.


Installation of Equipment

Commercial cooking equipment is comprised of several products that must work together to achieve the intended safe operation, prevent safety hazards and reduce overall risks. The installation of the cooking appliance and exhaust hood has been an area of interest for code officials for several years.

For the purposes of this article, the term “cooking appliance” refers to any device or apparatus used for heating or cooking of food. ;The mechanical codes (International Mechanical Code and Uniform Mechanical Code)and NFPA 96 provide the specific installation requirements for kitchen exhaust systems, and define which cooking appliances are permitted to be installed without an exhaust hood. A significant difference between the model mechanical codes and NFPA 96 is that the former provides a prescriptive method and requirements for fabrication of an exhaust hood on site while the latter(NFPA 96)prohibits field fabricated exhaust hoods.

The term “equipment” refers to related piping, ducts, vents, control devices and other components of systems other than cooking appliances. The chart below describes the type of equipment or appliance and the governing sections of the IMC, NFPA 96andUMC.

Type of Equipment or Appliance




Exhaust hoods


Chapter 5

Section 508.0

Grease ducts


Chapter 6

Section 510.0

Grease filters


Chapter 6

Section 509.0

Exhaust fans


Chapter 8

Section 511.0

Cooking appliances

Chapter 9

Chapter 12

Chapter 9

The model fire codes contain requirements for the type of automatic fire-extinguishing system that must be included in an installation. Section 904.12of the IFC and Section 50.4of NFPA 1have requirements for the design, installation, testing and maintenance of suppression systems that must be installed based on the type of commercial cooking appliances and related hood and duct system.

A “hood” is defined by NFPA 96 as a device provided for a cooking appliance(s) to direct and capture grease-laden vapors and exhaust gases. A Type I hood is a kitchen hood for collecting and removing grease vapors and smoke. A Type II hood is a general kitchen hood for collecting and removing steam vapor, heat, odors and products of combustion.

commercial cooking smoke nuisance Cooking appliances that produce grease or smoke as a result of the cooking process are required to be installed under a Type I hood. In the definitions of the model codes, various types of cooking appliances are grouped and designated as either light-duty, medium-duty, heavy-duty or extra-heavy-duty. The duty designation of the appliance is used to correlate with the required minimum exhaust air flow of the hood above an appliance. For non-listed hoods, the hood minimum exhaust capacity(amount of air flow)is either determined by the hood size; for listed hoods, capacity is determined through certification to UL 710,Standard for Exhaust Hoods for Commercial Cooking Equipment. When there are multiple appliances of varying duty types grouped under a single exhaust hood, the hood is sized for the heaviest duty appliance. When gas-fired cooking appliances are moveable for cleaning purposes, the appliance needs to have proper restraints and gas connections to the building service complying with the fuel gas code in accordance with the fire code and the manufacturer’s installation instructions.

The clearances to combustible materials and the cooking appliances, location of the hood and grease ducts, and the capacity of field constructed exhaust hoods and grease ducts to capture and remove the cooking effluent are covered in Chapter 5 of the mechanical codes. Exhaust hoods certified to UL 710, Standard for Exhaust Hoods for Commercial Cooking Equipment, and grease ducts certified to UL 1978,Standard for Grease Ducts, are evaluated for clearances to combustible materials and the capacity of the equipment to capture and remove the cooking effluent, based on performance testing. Certified equipment is required to be installed in accordance with its certification and the manufacturer’s installation instructions.

However, not all cooking appliances require an exhaust hood according to model codes. There are three types of cooking appliances that can be used without a hood:

  1. Recirculating systems that are certified and labeled in accordance with UL 710B, Standard for Recirculating Systems. These are self-contained factory-built units that include a cooking appliance, collection hood, grease filters and fire suppression system. These systems are evaluated for reduced grease emissions. After capturing the cooking effluent and filtration, the air is recirculated back into the room.    
  2. Cooking appliances that have reduced grease emissions as determined through the testing requirements in UL 197, Standard for Commercial Electric Cooking Appliances. To qualify as having reduced grease emissions, the appliance effluent must be shown to contain 5 mg/m3 or less of grease when tested at an exhaust flow rate of 500 cfm (0.236 m3/s). Only those cooking appliances that comply with this additional testing are identified in the certification and the manufacturer’s installation instructions.  
  3. Cooking appliances equipped with integral down-draft exhaust systems certified and labeled for the application in accordance with NFPA 96. These systems are ducted to outside of the building.

Commercial kitchen exhaust hood systems are required to operate during the cooking operation. Automatic controls are used to activate the exhaust fans when any of the cooking appliances served by the exhaust hood is turned on. Alternatively, interlocks can prevent operation of the appliance if the exhaust fan is not turned on.

The model fire codes include requirements for the type of automatic fire-extinguishing system that must be included in the installation. Section 904.12 of the IFC and Section 50.4 of NFPA 1 have requirements for the design, installation, testing and maintenance of suppression systems that must be installed based on the type of commercial cooking appliances and related hood and duct system.

For more information regarding grease ducts and pollution control units, see the article in the September 2019 TCA:  Pollution Control Units for Commercial Cooking Systems: Then and Now.


Inspection, Testing and Maintenance

A significant potential hazard associated with commercial cooking equipment is the accumulation of cooking grease in hoods, ducts and associated appurtenances. Both model fire codes require periodic inspections by properly trained and qualified service personnel. The minimum frequency is once every six months, unless otherwise specified in the fire code based on cooking volume, cooking method, fuel source or manufacturer’s instructions. The maximum accumulation of grease permitted is 0.078 inch (2000 mm), as measured using a Depth Gauge Comb, before thorough cleaning to remove the grease accumulation is required. Please see NFPA 1 and the IFC reference Standard ANSI/IKECA C10, Standard for the Methodology for Cleaning of Commercial Kitchen Exhaust Systems, for further details on cleaning.

Inspectors should verify proper operation by checking the exhaust hood interface ensuring exhaust fans operate when any cooking appliance is in use. 

Following the inspection and/or cleaning, a dated certificate including the name of the service company and service technician is required to be available on the premises. The owner of the cooking system must be notified if any areas were inaccessible or not cleaned.

The automatic fire-extinguishing system is required to be inspected every six months by qualified service technicians following the equipment manufacturer’s service instructions. Code authorities should ensure all system’s fusible links of the metal alloy type are replaced at least semi-annually.  Unless a different temperature link is approved by the code authority, all replacement links must be of the same temperature rating as those replaced.

The number, size and location of certified Class K fire extinguishers are determined by the number of deep-fat fryers in the cooking line. Fire extinguishers should be visually inspected by the owner monthly and inspected and serviced annually, following the manufacturer’s instructions. A damaged or discharged fire extinguisher should be serviced or replaced.

The arrangement of cooking appliances under the hood should remain unchanged from the time of initial installation and approval. The proper type and location of both extinguishing agent discharge nozzles and fusible links depend on the type and location of cooking appliances being protected.  

The inspection of the commercial kitchen and cooking equipment should also ensure that all required signage from the time of installation for system operation and emergency situations is present and legible.

Any changes to the cooking line necessitates a re-evaluation of the installation for the following reasons:

  1. The automatic fire-extinguishing system are specifically designed and installed to address specific applications (like deep fat fryers) due to the differing hazards.
  2. The proper sizing of the exhaust system to ensure the exhaust rate of the system will properly capture and exhaust the cooking effluent to outside the building is affected by the type and location of the cooking appliances under the hood.  


Summary of Model Fire Code Requirements



2018 IFC Section* 

2018 NFPA 1 Section 

Hoods, grease-removal devices, fans, ducts and other appurtenances 

Initial install 

607.1 & 607.2 

Chapter 50 




TABLE 607.3.3.1 


TABLE 60.6.4 

Exhaust fan interlock 

Inspected/test (operation) 

IMC 507.1.1 

Inspection certificate 


607.3.3.3 & .14 

Automatic fire-extinguishing systems 


607.3.4 & 904.12.5 


Class K fire extinguisher(s) 


906.4 & 906.2 

50.4.11 & 13.6 

Arrangement of cooking appliances 





5003.5 & 

Securement of moveable cooking appliances 




IFC 607.4 

Cooking oil storage 




*NOTE: 2021 IFC requirements for commercial cooking equipment and operations were relocated to Section 606; cooking oil storage requirements were relocated to Section 607.


Cooking oil storage requirements

The safe and proper storage of cooking oil is also regulated by the IFC and NFPA 1 as a Class IIIB combustible liquid. When quantities exceed 60 gallons, cooking oil is required to be stored in metallic tanks that are certified and installed in accordance with UL 80, Steel Tanks for Oil-burner Fuels and Other Combustible Liquids, or UL 142, Steel Aboveground Tanks for Flammable and Combustible Liquids, and the tank manufacturer’s instructions. If stored in nonmetallic storage tanks, tanks must be certified in accordance with UL 2152, Standard for Special Purpose Nonmetallic Containers and Tanks for Specific Combustible or Noncombustible Liquids, be installed in accordance with the tank manufacturer’s instructions and not exceed 200 gallons (757 L) per tank. The storage of any cooking oil in other containers, typically its original shipping container, is limited to 60 gallons and the other applicable storage locations and safety requirements for a Class IIIB combustible liquid.

Cooking oil storage tanks must have both normal and emergency vents, and they are permitted to be vented to the inside of the building where installed. The cooking oil system may include metallic or nonmetallic piping, connections, fittings, valves, tubing, hose, pumps and other related components used for the transfer of cooking oil, provided the entire assembly design and construction is suitable for the anticipated working pressures, temperatures and structural stress. Materials must also be compatible for use with cooking oil.

In some cooking oil systems, the oil is heated prior to pumping to cooking equipment or may be at an elevated temperature when used oil is pumped from cooking appliances for temporarily stored prior to disposal. The IFC requires any electrical equipment used for heating of cooking oil in a storage system to be listed in accordance with UL 499, Standard for Electrical Heating Appliances, and installed in accordance with NFPA 70, National Electrical Code (NEC). The use of an electrical immersion heater in a nonmetallic cooking oil tank is prohibited. Any other electrical equipment used for the operation of a cooking oil storage system must also comply with NFPA 70.

Commercial cooking oil filters, certified to UL 1889, Standard for Commercial Filters for Cooking Oil, are used to filter the cooking oil used in deep-fat fryers usually found in commercial kitchens, restaurants or other locations where food is prepared. These filters consist of a pump motor to move oil to and from a deep fat fryer and may also include an integral oil heater. These filters are either stand-alone appliances or are built into a deep fat fryer.

The storage tank should be identified as either fresh or waste/used cooking oil and marked with the appropriate emergency responder identification marking, such as a sign complying with NFPA 704, Standard System for Identification of the Hazards of Materials for Emergency Response.


Available Resources

There are several resources available for code authorities, restaurant owners and designers, architects, and contractors to assist in achieving compliance with the code requirements for commercial cooking installations.

  1. Product iQTM:  Equipment and appliances for commercial cooking certified by UL can be located on the UL searchable database, using Product iQ. Product iQ, available at, is free to use, but does require a simple one-time registration.
  2. Inspection resources for code authorities:  An interactive illustrated diagram with quick links to all standards, guide information and UL certifications related to commercial cooking equipment and appliances. View this diagram at Commercial Cooking Equipment - UL Code Authoritie.
  3. Commercial Cooking and Food Service Equipment Marking and Application Guide:  UL has developed the Commercial Cooking and Food Service Equipment Marking and Application Guide for use by code authorities, contractors, installers, users, system designers and other interested parties to aid in understanding the basic components of these food service systems and the applicable codes and standards to achieve a  safe and code-compliant installation.

For further information or assistance, please contact UL’s Codes & Regulatory Services at

Pollution Control Units for Commercial Cooking Systems: Then and Now

Pollution control units are often required for commercial cooking hoods to reduce harmful emissions. Learn about the basic code requirements.

Commercial Cooking and Food Service Equipment Marking and Application Guide

New innovations in products, the expanded mobility of food services, the focus on a greener kitchen environment and the effort to save on energy costs are spurring new and established restaurateurs to be creative in food services design.

Interactive Diagram: Commercial Cooking Equipment

Access product categories, Standards, and UL Certification details through our interactive commercial cooking equipment diagram. 

The Code Authority Newsletter 2021 | Issue 1