Many commercial kitchens require ventilation hoods as part of their fire suppression systems. There are two types of hoods.
Type 1 hoods contain fire-extinguishing equipment. These hoods are required over appliances that produce grease-laden vapors or smoke. They must contain both automatic and manual methods of activation. The most common types are wet chemical extinguishing systems (UL 300) and carbon dioxide extinguishing systems. Existing fire sprinkler systems may be grandfathered in. UL 300-compliant systems are important because they are designed to allow for cooling and preventing fire reignition. If the system is not UL 300, it should be red tagged by the servicing company. Class K extinguishers must be present within 30 feet of commercial cooking equipment.
Type 2 hoods are for ventilation only. Type 2 hoods can be used with appliances that produce only heat/steam.
Both hood types must cover all cooking equipment. Electrical equipment that is installed inside of hoods must be installed in accordance with their listing (typically explosion proof cases).
Fire Suppression System
Monthly owner inspections are required ensure proper function. Inspections should make sure:
- Extinguishing system is in place and charged
- Nozzle blow-off caps are in place
- Tamper indicator seals are intact
- Maintenance tag is in place and current
- No obvious physical damage or condition that might prevent proper operation
If any problems are identified, they must be documented and corrected immediately.
Hood, Filters, Ducting, Fan, Grease Traps
Owners should inspect metal components of the system and clean as needed. Per NFPA 96, inspection for grease buildup varies, dependent upon fuel type and frequency of use as noted below:
- Systems using solid fuel – monthly
- Systems serving high-volume cooking operations – quarterly
- Systems serving moderate-volume cooking operations – semiannually
- Systems serving low-volume cooking operations – annually
If a measured amount using a depth gauge is .078 in. or more, the surfaces should be cleaned. Flammable solvents should not be used. Cleaning chemicals should not be applied to fusible links or other detection devices. Any holes in the hood or ducting must be plugged with an approved, UL-listed plug.
Per NFPA 17A, the fire suppression system should be inspected on a semiannual basis. Per NFPA 96, cooking equipment inspection and servicing should be made at least annually by properly trained and certified people.
NFPA 96 requires that filters be UL 1046 approved. Mesh filters are prohibited. NFPA 96 grease filters must be listed (UL). They must also be constructed of non-combustible material, rigid construction, and arranged so all air passes through them and not less than 45 degrees from horizontal in their installation. They require directional arrows or specific orientation so they cannot be installed improperly (upside down or backwards, etc.). These filters must also be easily accessible for removal, cleaning, and maintenance. They must be installed with a drip tray below their lower edges. Drip trays must be minimum effective size but may not exceed one gallon in capacity.
Employees should be trained on kitchen fire procedures. This training should include manual activation of the suppression system and use of a class K extinguisher as well as any site-specific requirements.
References: NFPA 17A – Wet chemical extinguishing systems, NFPA 96 – Ventilation Control and Fire Protection of Commercial Cooking Operations