Kitchen exhaust systems are an essential part of any commercial kitchen, designed to ventilate heat, smoke, grease, and fumes from cooking equipment. These systems play a crucial role in ensuring the safety and comfort of kitchen staff.  However, when poorly maintained, kitchen exhaust systems become a significant fire hazard. Fires originating from poorly maintained kitchen exhaust systems are avoidable but common and can cause extensive damage to property and even lead to loss of life.

The Importance of Proper Maintenance

A kitchen exhaust system typically consists of several components, including:

• Stainless steel exhaust hood – wall mounted or island configuration
• Grease traps and odour neutralising filters
• Sheet metal duct-work, cowls and louvres
• Kitchen supply / exhaust fans – In-line or roof mounted

Over time, grease and other flammable residues accumulate in these components, particularly in the ducts and filters. If left unchecked, this buildup can ignite when exposed to high temperatures, often resulting in destructive fires.

Regular maintenance is essential for preventing such hazards, ensuring the system operates efficiently, and complying with fire safety regulations. Over the years there have been some large fires which have resulted from poor maintenance, such as that of an Edgware Road Restaurant in July 2017.  The London Fire Brigade report: “The fire started in a restaurant’s ducting (extraction) system. It’s believed that hot fat and grease in the ducting caught fire and as the ducting ran the length of the building, the fire was able to spread up through the building.” The six-story mixed use building sustained damage to parts of the Ground and First Floors along with the Stairwells but luckily the swift action of the six fire engines and 35 fire fighters ensured there were no fatalities.  This event could have been avoided with preventative system maintenance.

Key Maintenance Tasks for Kitchen Exhaust Systems

Proper maintenance of kitchen exhaust systems requires regular cleaning, inspection, and testing of various components. The following tasks should be performed to ensure fire safety:

Inspection of Duct-work and Hoods
Inspect the duct-work and hoods for signs of damage, wear, or blockage. If ducts are clogged or damaged, they may impair airflow, increase heat, and promote the accumulation of flammable materials. Ensure all seams and joints are properly sealed to prevent grease leaks.

Grease Removal
Grease buildup in exhaust ducts and filters is one of the most significant fire risks. Ducts, hoods, and filters should be thoroughly cleaned at regular intervals to prevent grease accumulation.

Cleaning Filters and Fans
The filters in kitchen exhaust systems trap grease and debris, which need to be regularly cleaned to maintain efficiency. Fans should also be inspected to ensure they are functioning properly and not obstructed by grease or debris.

Check Fire Suppression Systems
Many kitchen exhaust systems are equipped with automatic fire suppression systems. These systems should be inspected and tested annually to ensure they will function properly in the event of a fire. The fire suppression system is critical to preventing the spread of a fire if it originates in the exhaust system.

Test System Operation
Periodically test the exhaust system to ensure that the fans are operating at the correct speed and that airflow is adequate. Inadequate ventilation can result in poor air quality and increased fire risk.

Regulatory Standards for Kitchen Exhaust Maintenance

Compliance with local fire safety codes and regulations is critical for ensuring the safe operation of kitchen exhaust systems. Several countries have established guidelines to promote the safe maintenance and operation of these systems.

Australia

In Australia, the maintenance of kitchen exhaust systems is regulated by AS 1851:2012  (Maintenance of Fire Protection Systems and Equipment).  According to AS 1851, kitchen exhaust systems must be inspected and cleaned regularly to ensure they comply with fire safety standards. The standard recommends that grease filters be cleaned and ducts inspected and cleaned as necessary, typically every three to six months, depending on the cooking volume.

AIRAH Best Practice Guide: Commercial Kitchen Exhaust Management, 2022 provides full detail on kitchen exhaust system maintenance.  Many insurance policies require adherence to AS 1851-2012 or similar standards for kitchen exhaust system maintenance. 

Canada

The NFPA 96 (Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations) governs the maintenance of commercial kitchen exhaust systems including the inspection and cleaning of grease removal devices and ducts at regular intervals to prevent grease buildup.

United Kingdom

BS EN 15780 (Ventilation for Buildings – Ductwork – Cleanliness of Ventilation Systems) and BESA TR19 provide key guidance for maintaining kitchen exhaust systems. TR19 is the industry-recognised standard used by building services contractors and insurers when carrying out duct cleaning to ensure systems are cleaned and maintained to a compliant, safe standard.

Conclusion

Maintaining kitchen exhaust systems is vital to fire safety in commercial kitchens. The risk of fire from a poorly maintained system is real and can cause significant property damage, financial loss, and even loss of life. Regular inspections and cleaning, along with adherence to national and international standards, are key to preventing these incidents.

By following the recommendations set out in standards like AS 1851, NFPA 96, BS EN 15780 and TR19, businesses can ensure that their kitchen exhaust systems are functioning safely and efficiently. Regular maintenance, proper cleaning, and compliance with fire safety regulations not only protect against the risks of fire but also improve the overall efficiency and longevity of the equipment.

Author: Louise Gardner, General Manager