Grease that builds up in the hood, filters, ductwork and fan is fuel. A fire that starts on the cooking line can travel through the duct to the roof and to other floors of the building. Cleaning frequency is therefore a fire-safety question, not a housekeeping one.
NFPA 96 requirements
NFPA 96 is the internationally recognised standard for fire safety in commercial kitchen exhaust systems. It sets an inspection schedule based on the type and volume of cooking. When an inspection finds grease buildup, the system is cleaned down to bare metal.
| Type of operation | Inspection frequency |
|---|---|
| Solid-fuel cooking (wood, charcoal) | Monthly |
| High volume: 24-hour operation, charbroiling, wok cooking | Quarterly |
| Moderate volume | Semi-annually |
| Low volume: seasonal businesses, places of worship, day camps | Annually |
In a busy kitchen, a quarterly inspection almost always finds enough buildup to require cleaning. In an institutional kitchen that cooks one shift a day, the interval is set by what is actually found in the ducts.
Scope of a full clean
- The hood and grease filters.
- The full length of the ductwork, horizontal and vertical runs, through access panels.
- The exhaust fan, including the wheel and housing.
- The discharge point on the roof.
Cleaning only the hood and filters leaves most of the grease in the duct and fan, exactly where fire spreads fastest.
Israeli requirements: SI 1001 Part 6 and fire-authority approval
In Israel, Israeli Standard SI 1001 Part 6 covers kitchen exhaust systems, and the fire authorities rely on it in their requirements for businesses that cook. Opening a business or renewing a business licence usually requires a certificate confirming the system has been cleaned, known in the trade as "Form 16".
The binding requirement for each business is set by its business licence and by the local fire authority. Check it with the authority before the inspection, not after.
Indicators that cleaning is due
- Grease dripping from the hood or filters.
- Weak extraction and smoke lingering in the kitchen.
- Noise or vibration from the fan.
- Grease stains around the roof discharge.
Want to know the condition of your system? Book a site survey or read more on standards and frequencies.