518.0 Downdraft Appliances

A downdraft appliance ventilation system containing, or for use with appliances used in processes that produce, smoke or grease-laden vapors shall be equipped with components that are in accordance with the following:

1. The clearance requirements in accordance with Section 507.3.
2. The primary collection means designed for collecting cooking vapors and residues in accordance with the requirements of Section 508.0.
3. Grease removal devices that comply with Section 509.0.
4. Special-purpose filters as listed in accordance with UL 1046.
5. Exhaust ducts that comply with Section 510.0.
6. The air movement requirements in accordance with Section 511.2.1 and Section 511.2.2.
7. Auxiliary equipment (such as particulate and odor removal devices) are in accordance with Section 512.0.
8. Fire-extinguishing equipment that is in accordance with the requirements of Section 513.0, and as specified in Section 518.3.
9. The use and maintenance requirements in accordance with Section 514.0.
10. The minimum safety requirements in accordance with Section 515.0. [NFPA 96:15.1.1]

The downdraft appliance ventilation system shall be capable of capturing and containing the effluent discharge from the appliance(s) it is serving. [NFPA 96:15.1.2]

Fire-extinguishing equipment on a downdraft appliance ventilation system shall comply with the following:

1. Cooking surface, duct, and plenum protection shall be provided.
2. Not less than one fusible link or heat detector shall be installed within an exhaust duct opening in accordance with the manufacturer's listing.
3. A fusible link or heat detector shall be provided above the protected cooking appliance and in accordance with the extinguishing system manufacturer's listing.
4. A manual activation device shall be provided as part of the appliance at a height approved by the Authority Having Jurisdiction.
5. Portable fire extinguishers shall be installed in accordance with Section 513.11. [NFPA 96:15.2]

A listed downdraft appliance ventilation system employing an integral fire-extinguishing system including detection systems that has been evaluated for grease and smoke capture, fire extinguishing, and detection shall be considered to be in accordance with Section 518.3. [NFPA 96:15.2.1]

The downdraft appliance ventilation system shall be provided with interlocks such that the cooking fuel supply will not be activated unless the exhaust and supply air system have been activated. [NFPA 96:15.2.2]

An airflow switch or transducer shall be provided after the last filter component to ensure that a minimum airflow is maintained. [NFPA 96:15.3.1]

The airflow switch or transducer shall open the interlock circuit where the airflow is less than 25 percent the system's normal operating flow or less than 10 percent its listed minimum rating, whichever is less. [NFPA 96:15.3.2]

The airflow switch or transducer shall be a manual reset device or circuit. [NFPA 96:15.3.3]

Surfaces located directly above the cooking appliance shall be of noncombustible or limited-combustible materials. [NFPA 96:15.4]