CMC · California Mechanical Code
Grease removal devices and grease duct construction
Commercial kitchen hoods must have listed grease removal devices (metal, rigid, drainable) installed so filters are at least 18 inches from cooking surfaces (4 feet for solid‑fuel) and grease ducts stay 18 inches from combustibles unless a listed enclosure allows less; follow product listings and manufacturer instructions.
Last reviewed: July 6, 2026
What the code requires
The California Mechanical Code requires that commercial cooking hoods use listed grease removal devices and grease filters, installed with minimum separation distances from cooking surfaces, and that grease ducts meet required clearances to combustibles unless protected by listed enclosures. The controlling sections are § 509.0 (grease removal devices), § 507.4 (clearance requirements), and § 507.4.6.3 (clearance options for field‑applied and factory‑built grease duct enclosures). See § 509.1 for listing and filter requirements and § 507.4 for basic clearance rules.
Maintain listed grease filters and the minimum clearances (or use a listed enclosure) so grease ducts and hood filters can be cleaned and so heat/flame cannot directly impinge the filters or nearby combustibles.
Requirements in detail
Key defined terms (first use)
- Grease removal device — a component or system that captures and concentrates airborne grease from kitchen exhaust (defined in the code). § 509.0
- Grease filter — a removable component that captures grease and directs it to a collection point. § 509.0
- Clearance — the required separation from hoods, ducts, filters, or fans to combustible, limited‑combustible, or noncombustible materials. § 507.4
Basic rules (what you must provide)
- Provide listed grease filters or other listed grease removal devices for commercial cooking operations. § 509.1
- Grease filters must be constructed of steel or other noncombustible material, be rigid, and be listed (UL 1046 where applicable). § 509.2.3
- The vertical separation from the cooking surface to the grease removal device must be as great as possible, but not less than 18 inches (457 mm) in general, and 4 feet (1219 mm) for solid‑fuel or solid‑fuel–type broilers unless a listed product or exception applies. § 509.2; § 509.2.1
- Where grease removal devices are closer than 18 inches (457 mm) to the appliance flue outlet, the device must be protected from combustion gas outlets or direct flame impingement (for example, by a steel or stainless steel baffle plate sized to force flame/combustion gases to travel at least 18 inches (457 mm) from the heat source). § 509.2.2 – 509.2.2.3
Grease filter and drip hardware specifics
- Mesh filters: not permitted unless evaluated as an integral part of a listed exhaust hood or listed in conjunction with a primary filter per UL 1046. § 509.1.1
- Angle: grease filters that drain must be installed at an angle of not less than 45 degrees from horizontal. § 509.2.3.3
- Drip trays: filters must have grease drip trays that drain into an enclosed metal container not exceeding 1 gallon (4 L). § 509.2.4.1 – 509.2.4.2
Clearances and enclosure options (grease ducts and hoods)
- Default clearances when no enclosure is provided: 18 inches (457 mm) to combustible materials, 3 inches (76 mm) to limited‑combustible materials, and 0 inches to noncombustible materials. § 507.4
- If a product is listed for reduced clearances, its listing controls. § 507.4.1
- Clearance reduction systems allowed by code include specific sheet‑metal spacers or mineral‑wool/ceramic fiber construction; minimum clearances for those systems are stated in § 507.4.2 and subsections. § 507.4.2 – 507.4.2.2
- Field‑applied and factory‑built grease‑duct enclosures must demonstrate mechanical and structural integrity for expected conditions. § 507.4.6
- The code requires that listed grease duct enclosure documentation clearly identify the applicable clearance options (these are the options you can rely on): open combustible construction, closed combustible construction (with or without specified ventilation), and rated shaft (with or without specified ventilation), each at the manufacturer’s requested dimensions. § 507.4.6.3
Decision‑relevant dimensions / values
| Item | Required minimum / condition | Code Reference |
|---|---|---|
| Minimum separation from cooking surface to grease removal device (general) | 18 inches (457 mm) | § 509.2 |
| Minimum separation for solid‑fuel or charbroiler applications | 4 feet (1219 mm) | § 509.2.1 |
| Minimum separation allowed for equipment without exposed flame (exception) | 6 inches (152 mm) | § 509.2.1 Exception (1) |
| Clearance to combustible materials (no enclosure) | 18 inches (457 mm) | § 507.4 |
| Clearance to limited‑combustible materials (no enclosure) | 3 inches (76 mm) | § 507.4 |
| Clearance to noncombustible materials (no enclosure) | 0 inches (0 mm) | § 507.4 |
| Angled filter installation | ≥ 45 degrees from horizontal | § 509.2.3.3 |
| Grease drip tray capacity limit | ≤ 1 gallon (4 L) | § 509.2.4.1 – § 509.2.4.2 |
| Enclosure clearance options (must be on listing) | Open combustible / Closed combustible / Rated shaft (manufacturer’s dimensions) | § 507.4.6.3 |
Exceptions & special cases
- A grease removal device that is part of a listed hood assembly may be installed per the terms of that listing and the manufacturer’s instructions rather than strict § 509.2 distances. § 509.2 Exception (3)
- For cooking equipment that does not have exposed flame and where flue gases bypass the grease removal device, the general 18‑inch separation may be reduced to 6 inches (152 mm). § 509.2.1 Exception (1)
- Where a grease duct is listed for zero clearance or otherwise protected by a listed material/product, contact with noncombustible supporting surfaces may exceed 50% contact length restrictions (see § 507.4.7 & § 507.4.7.2). § 507.4.7; § 507.4.7.2
If you need manufacturer‑specific reduced clearances or specific installation details for a factory‑built grease duct system, the code defers to the product listing and the listing documentation; those items are not reproduced in the retrieved code text and must be obtained from the product listing/manufacturer.
Common mistakes
- Installing an unlisted or mesh grease filter where a listed filter is required — mesh filters are disallowed unless specifically listed for the application. § 509.1.1
- Placing grease filters too close to the heat source (less than 18 inches) without the required baffle or protection. § 509.2; § 509.2.2
- Assuming a “close fit” to combustible walls is permitted without verifying either the default clearance (18 inches) or using a listed enclosure / reduction system. § 507.4; § 507.4.6.3
- Not providing accessible openings for cleaning—interior surfaces and ducts must be accessible for cleaning and inspection. (See system requirements in Chapter 507.) § 507.2.5; § 510.1.4
Worked example
Scenario: Restaurant installs a gas charbroiler (open flame) with a Type I hood and removable grease filters.
The chef’s cooking surface is at 36 inches above finished floor. For a solid‑fuel or solid‑fuel‑type broiler the grease filter lower edge must be at least 4 feet (48 inches) above the cooking surface. Per § 509.2.1, the lower edge of the grease removal device must be ≥ 48 inches above the 36‑inch cooking surface (i.e., the filter lower edge should be at or above 84 inches AFF).
If the filter cannot be kept that far (space constraints) and the filter ends up less than 18 inches from the appliance flue outlet, install a steel or stainless steel baffle plate so that flame/combustion gases travel at least 18 inches from the heat source to the grease removal device, with the baffle located at least 6 inches from the grease removal device. Follow § 509.2.2 – 509.2.2.4 for sizing and location.
The hood and grease duct pass near a combustible‑framed wall. If no enclosure is used, the grease duct must be kept 18 inches from that combustible surface per § 507.4. Alternatively, provide a listed field‑applied grease duct enclosure and use the manufacturer’s listed clearance option (for example, a closed combustible construction clearance at the manufacturer’s stated dimensions) per § 507.4.6.3.
Ensure the grease filters are listed, constructed of steel or other noncombustible material, are angled ≥ 45°, have drip trays draining to an enclosed metal container ≤ 1 gallon, and are easily removable for cleaning in accordance with § 509.2.3 – § 509.2.4.
Related provisions
- § 509.1 — Grease removal devices; listing requirements.
- § 509.2 — Installation details for grease removal devices (distances, baffles, filter construction).
- § 509.3 — Solid‑fuel grease removal device specifics (see § 517.0).
- § 507.2 — Type I hood exhaust system requirements, maintenance and access requirements.
- § 510.1 – § 510.3 — Exhaust duct system general rules, slope, drains, and access openings (cleanability).
- § 507.4.2 – § 507.4.2.2 — Specific clearance‑reduction construction options (sheet metal + spacers; mineral wool batt).
If you want manufacturer listing details or product installation manuals (for specific factory‑built grease ducts or listed enclosures), those are not reproduced in the code excerpts retrieved here and must be obtained from the product listing or manufacturer.
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 507.6 High relevance — show source text
507.6 Notification of Change . . . . . . . . . 111
507.7 Pharmaceutical Compounding Exhaust Discharge . . . . . . . . . . . . 111
508.0 Type I Hoods . . . . . . . . . . . . . . . . 111
508.1 Where Required . . . . . . . . . . . . . . 111
508.2 Listed Type I Hood Assemblies . . 111
508.3 Construction of Type I Hoods . . . . 111
508.4 Supports . . . . . . . . . . . . . . . . . . . . 112
508.5 Hood Size . . . . . . . . . . . . . . . . . . . 112
Table 508.5.1.2 Extra-Heavy-Duty Cooking Appliance Airflow . . . . . . . . . . . . . 113
Table 508.5.1.3 Heavy-Duty Cooking Appliance
Airflow. . . . . . . . . . . . . . . . . . . . . . 113
Table 508.5.1.4 Medium-Duty Cooking Appliance
Airflow. . . . . . . . . . . . . . . . . . . . . . 113
Table 508.5.1.5 Light-Duty Cooking Appliance
Airflow. . . . . . . . . . . . . . . . . . . . . . 113
508.6 Solid-Fuel Hood Assemblies . . . . 114
508.7 Exhaust Outlets . . . . . . . . . . . . . . 114
509.0 Grease Removal Devices in
Hoods . . . . . . . . . . . . . . . . . . . . . . 114
509.1 Grease Removal Devices. . . . . . . 114
509.2 Installation . . . . . . . . . . . . . . . . . . 114
509.3 Solid-Fuel Grease Removal
Devices. . . . . . . . . . . . . . . . . . . . . 115
510.0 Exhaust Duct Systems . . . . . . . . . 115
510.1 General. . . . . . . . . . . . . . . . . . . . . 115
510.2 Clearance . . . . . . . . . . . . . . . . . . . 115
510.3 Openings . . . . . . . . . . . . . . . . . . . 115
510.4 Listed Grease Ducts . . . . . . . . . . . 116
510.5 Other Grease Ducts . . . . . . . . . . . 116
510.6 Exterior Installations . . . . . . . . . . . 117
xxxii
510.7 Interior Installations . . . . . . . . . . . 118
510.8 Underground Installations. . . . . . . 118
510.9 Termination of Type I Hood Exhaust System . . . . . . . . . . . . . . 119
510.10 Solid-Fuel Duct Systems . . . . . . . 120
511.0 Air Movement . . . . . . . . . . . . . . . . 120
511.1 Exhaust Fans for Commercial
CMC § 509.0 High relevance — show source text
509.0 Grease Removal Devices in Hoods.
509.1 Grease Removal Devices. Listed grease filters or other listed grease removal devices intended for use with commercial cooking operations shall be provided. Listed grease filters and grease removal devices that are removable but not an integral component of a specific listed exhaust hood shall be listed in accordance with UL 1046 and shall be designated on the filter. {NFPA 96:6.1.1, 6.1.2} 509.1.1 Grease Filters, Mesh-Type. Mesh filters shall not be used unless evaluated as an integral part of a listed exhaust hood or listed in conjunction with a primary filter in accordance with UL 1046. {NFPA 96:6.1.3}
509.2 Installation. The distance between the grease removal device and the cooking surface shall be as great as possible but not less than 18 inches (457 mm). [NFPA 96:6.2.1.1]
509.2.1 Vertical Distance. Where grease removal devices are used in conjunction with solid fuel or solid fueltype broilers, including gas or electrically heated charbroilers, a minimum vertical distance of 4 feet (1219 mm) shall be maintained between the lower edge of the grease removal device and the cooking surface. [NFPA 96:6.2.1.2]
Exceptions:
(1) For cooking equipment without exposed flame and where flue gases bypass grease removal devices, the minimum vertical distance shall be permitted to be reduced to not less than 6 inches (152 mm). [NFPA 96:6.2.1.3]
(2) Where a grease removal device is listed for separation distances less than those required in Section
509.2 and Section 509.2.1, the listing requirements shall be permitted. [NFPA 96:6.2.1.4]
(3) Grease removal devices supplied as part of listed hood assemblies shall be installed in accordance with the terms of the listing and the manufacturer’s instructions. [NFPA 96:6.2.1.5]
509.2.2 Grease Removal Device Protection. Where the distance between the grease removal device and the appliance flue outlet (heat source) is less than 18 inches (457 mm), grease removal devices shall be protected from combustion gas outlets and from direct flame impingement occurring during normal operation of cooking appliances producing high flue gas temperatures.
[NFPA 96:6.2.2.1]
509.2.2.1 Installation. This protection shall be permitted to be accomplished by the installation of a steel or stainless steel baffle plate between the heat source and the grease removal device. [NFPA 96:6.2.2.2]
509.2.2.2 Size and Location. The baffle plate shall be sized and located so that flames or combustion gases travel a distance not less than 18 inches (457 mm) from the heat source to the grease removal device. [NFPA 96:6.2.2.3]
509.2.2.3 Clearance. The baffle shall be located not less than 6 inches (152 mm) from the grease removal device. [NFPA 96:6.2.2.4]
509.2.3 Grease Filters. Grease filters shall be listed
CMC § 509.1 High relevance — show source text
Hoods . . . . . . . . . . . . . . . . . . . . . . 114
509.1 Grease Removal Devices. . . . . . . 114
509.2 Installation . . . . . . . . . . . . . . . . . . 114
509.3 Solid-Fuel Grease Removal
Devices. . . . . . . . . . . . . . . . . . . . . 115
510.0 Exhaust Duct Systems . . . . . . . . . 115
510.1 General. . . . . . . . . . . . . . . . . . . . . 115
510.2 Clearance . . . . . . . . . . . . . . . . . . . 115
510.3 Openings . . . . . . . . . . . . . . . . . . . 115
510.4 Listed Grease Ducts . . . . . . . . . . . 116
510.5 Other Grease Ducts . . . . . . . . . . . 116
510.6 Exterior Installations . . . . . . . . . . . 117
xxxii
510.7 Interior Installations . . . . . . . . . . . 118
510.8 Underground Installations. . . . . . . 118
510.9 Termination of Type I Hood Exhaust System . . . . . . . . . . . . . . 119
510.10 Solid-Fuel Duct Systems . . . . . . . 120
511.0 Air Movement . . . . . . . . . . . . . . . . 120
511.1 Exhaust Fans for Commercial
Cooking Operations . . . . . . . . . . . 120
511.2 Airflow. . . . . . . . . . . . . . . . . . . . . . 121
511.3 Makeup Air . . . . . . . . . . . . . . . . . . 122
511.4 Common Duct (Manifold) Systems . . . . . . . . . . . . . . . . . . . . 122
511.5 Solid-Fuel Air Movement
Requirements . . . . . . . . . . . . . . . . 122
512.0 Auxiliary Equipment . . . . . . . . . . . 122
512.1 Dampers . . . . . . . . . . . . . . . . . . . . 122
512.2 Electrical Equipment. . . . . . . . . . . 122
512.3 Other Equipment . . . . . . . . . . . . . 123
512.4 Solid-Fuel Auxiliary Equipment. . . 123
513.0 Fire-Extinguishing Equipment. . . . 123
513.1 General. . . . . . . . . . . . . . . . . . . . . 123
513.2 Types of Equipment . . . . . . . . . . . 123
513.3 Simultaneous Operation . . . . . . . . 124
513.4 Fuel and Electric Power Shutoff . . 125
513.5 Manual Actuation . . . . . . . . . . . . . 125
513.6 System Annunciation . . . . . . . . . . 125
513.7 Special Design and Application . . 125
513.8 Review and Certification. . . . . . . . 125
CMC § 508.5.2.1 High relevance — show source text
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508.5.2.1 Installation. Noncanopy-type commercial cooking hoods shall be installed with the edge of the hood set back not more than 1 foot (305 mm) from the edge of the cooking surface, and the vertical distance between the lip of the hood and the cooking surface shall not exceed 3 feet (914 mm). 508.5.2.2 Capacity. In addition to other requirements for hoods specified in this section, the volume of air exhausting through a noncanopy-type hood to the duct system shall be not less than 300 cubic feet per minute per lineal foot [(ft [3] /min)/ft)] [0.464 (m [3] /s)/m] of cooking equipment. Listed noncanopy exhaust hoods and filters shall be sized and installed in accordance with the terms of their listing and the manufacturer’s installation instructions.
508.5.3 Labeling. Type I hoods shall bear a label indicating the exhaust flow rate in cubic feet per minute per lineal foot [(m [3] /s)/m].
508.6 Solid-Fuel Hood Assemblies. Where solid-fuel cooking equipment is to be used, the solid-fuel hood assembly shall be in accordance with Section 517.0.
508.7 Exhaust Outlets. An exhaust outlet within an unlisted hood shall be located so as to optimize the capture of particulate matter. Each outlet shall serve not more than a 12 foot (3658 mm) section of an unlisted hood.
509.0 Grease Removal Devices in Hoods.
509.1 Grease Removal Devices. Listed grease filters or other listed grease removal devices intended for use with commercial cooking operations shall be provided. Listed grease filters and grease removal devices that are removable but not an integral component of a specific listed exhaust hood shall be listed in accordance with UL 1046 and shall be designated on the filter. {NFPA 96:6.1.1, 6.1.2} 509.1.1 Grease Filters, Mesh-Type. Mesh filters shall not be used unless evaluated as an integral part of a listed exhaust hood or listed in conjunction with a primary filter in accordance with UL 1046. {NFPA 96:6.1.3}
509.2 Installation. The distance between the grease removal device and the cooking surface shall be as great as possible but not less than 18 inches (457 mm). [NFPA 96:6.2.1.1]
509.2.1 Vertical Distance. Where grease removal devices are used in conjunction with solid fuel or solid fueltype broilers, including gas or electrically heated charbroilers, a minimum vertical distance of 4 feet (1219 mm) shall be maintained between the lower edge of the grease removal device and the cooking surface. [NFPA 96:6.2.1.2]
Exceptions:
(1) For cooking equipment without exposed flame and where flue gases bypass grease removal devices, the minimum vertical distance shall be permitted to be reduced to not less than 6 inches (152 mm). [NFPA 96:6.2.1.3]
(2) Where a grease removal device is listed for separation distances less than those required in Section
CMC § 507.2.4 Medium relevance — show source text
507.2.4 Multitenant Applications. Multitenant applications shall require the concerted cooperation of design, installation, operation, and maintenance responsibilities by tenants and by the building owner. [NFPA 96:4.1.7]
507.2.5 Interior Surfaces. All interior surfaces of the
exhaust system shall be accessible for cleaning and inspection purposes. [NFPA 96:4.1.8]
507.2.6 Used in Other Applications. Cooking equipment used in fixed, mobile, or temporary concessions, such as trucks, buses, trailers, pavilions, tents, or any form of roofed enclosure, shall comply with this chapter. {NFPA 96:1.1.3}
507.3 Listed Devices. Penetrations shall be sealed with listed devices in accordance with the requirements of Section 507.3.1.
507.3.1 Penetration. Devices that require penetration of a Type I hood or grease duct, such as pipe and conduit penetration fittings and fasteners, shall be listed in accordance with UL 710 or UL 1978. Seams, joints, and penetrations of the hood enclosure shall comply with Section 508.3.2. Seams, joints, and penetrations of the ductwork shall comply with Section 510.5.3. 507.4 Clearance. Where enclosures are not required, hoods, grease removal devices, exhaust fans, and ducts shall have a clearance of at least 18 inches (457 mm) to combustible material, 3 inches (76 mm) to limited-combustible material, and 0 inches (0 mm) to noncombustible material. [NFPA 96:4.2.1]
507.4.1 Listed. Where a hood, duct, or grease removal device is listed for clearances less than those required in Section 507.4, the listing requirements shall be permitted. [NFPA 96:4.2.2]
507.4.2 Clearance Reduction. Where a clearance reduction system consisting of 0.013 of an inch (0.33 mm) (28 gauge) sheet metal spaced out 1 inch (25.4 mm) on noncombustible spacers is provided, there shall be a minimum of 9 inches (229 mm) clearance to combustible material. [NFPA 96:4.2.3.1]
507.4.2.1 Mineral Wool Batts or Ceramic Fiber Blanket. Where a clearance reduction system consisting of 0.027 of an inch (0.686 mm) (22 gauge) sheet metal on 1 inch (25.4 mm) mineral wool batts or ceramic fiber blanket reinforced with wire mesh or equivalent spaced 1 inch (25.4 mm) on noncombustible spacers is provided, there shall be a minimum of 3 inches (76 mm) clearance to combustible material. [NFPA 96:4.2.3.2]
507.4.2.2 Field-Applied Grease Duct Enclo- sure. Where a clearance reduction system consisting of a listed and labeled field-applied grease duct enclosure material, system, product, or method of construction specifically evaluated for such purpose in accordance with ASTM E2336, the required clearance shall be in accordance with the listing.
[NFPA 96:4.2.3.3]
CMC § 3.3.48 Medium relevance — show source text
Utility Gas. See Fuel Gas.
Gas Convenience Outlet. A permanently mounted, handoperated device providing a means for connecting and disconnecting an appliance or an appliance connector to the gas supply piping. [NFPA 54:3.3.48]
Gas Piping. An installation of pipe, valves, or fittings that are used to convey fuel gas, installed on any premises or in a building.
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DEFINITIONS
Gas Piping System. An arrangement of gas piping or regulators after the point of delivery and each arrangement of gas piping serving a building, structure, or premises, whether individually metered or not. Generator. A device equipped with a means of heating used in an absorption system to drive refrigerant out of solution. GeoMicroDistrict. A collection of building and facilities on an independently pumped ambient temperature loop (ATL) that supplies or receives energy. An independent segment served by a thermal highway. Geothermal Energy System. A system that exchanges thermal energy between the earth, subsurface water, and/or bodies of water, for the purposes of space heating and cooling, and/or water heating. Geothermal Energy System, Closed-Loop. A closed-loop hydronic geothermal system that uses one or more heat exchangers submerged in a body of water or buried in the ground, fluidly coupled to one or more heat exchangers or heat pumps serving one or more conditioned spaces or thermal storage vessels. Geothermal Energy System, Open-Loop. An open-loop geothermal energy system draws in surface or ground water, passes it through one or more heat exchangers and/or heat pumps, and then discharges the water back into the environment.
Grade. A reference plane representing the average finished ground level adjoining the building at exterior walls. Gravity Heating System. A heating system consisting of a gravity-type warm air furnace, together with all air ducts or pipes and accessory apparatus installed in connection therewith.
Gravity-Type Floor Furnace. A floor furnace depending primarily on circulation of air by gravity. This classification also includes floor furnaces equipped with booster-type fans that do not materially restrict free circulation of air by gravity flow when such fans are not in operation. [NFPA 211:3.3.79.12.2] Grease. Rendered animal fat, vegetable shortening, and other such oily matter used for the purposes of and resulting from cooking, preparing foods, or both. [NFPA 96:3.3.29] Grease might be liberated and entrained with exhaust air or might be visible as a liquid or solid. Grease Filter. A removable component of the grease removal system designed to capture grease and direct it to a safe collection point. [NFPA 96:3.3.24.1] Grease Filter, Mesh-Type. A filter construction consisting of a net made from intersecting strands with a space between each strand. [NFPA 96:3.3.24.2] Grease Removal Devices. A system of components designed and intended to process vapors, gases, or air as it is drawn through such devices by collecting the airborne grease particles and concentrating them for further action at some future time, leaving the exiting air with a lower amount of combustible matter.
CMC § 517.4.3 Medium relevance — show source text
517.4.3 Prohibited. Wall terminations of solid-fuel exhaust systems shall be prohibited. [NFPA 96:15.4.4]
517.5 Grease Removal Devices for Solid-Fuel Cook- ing. Grease removal devices shall be constructed of steel or stainless steel or be approved for solid-fuel cooking. [NFPA 96:15.5.1] 517.5.1 Spark Arrester Devices. If airborne sparks and embers can be generated by the solid fuel cooking operation, spark arrester devices shall be used prior to using the grease removal device, to minimize the entrance of these sparks and embers into the grease removal device and into the hood and the duct system. [NFPA 96:15.5.2] 517.5.2 Filters. Filters shall be a minimum of 4 feet (1219 mm) above the appliance cooking surface. [NFPA 96:15.5.3] 517.6 Air Movement for Solid-Fuel Cooking. Exhaust system requirements shall comply with Section 511.0 for hooded operation or shall be installed in accordance with the manufacturer’s recommendations for unhooded applications.
[NFPA 96:15.6.1]
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517.6.1 Replacement Air. A replacement or makeup air system shall be provided to ensure a positive supply of replacement air at all times during cooking operations.
[NFPA 96:15.6.2]
517.6.2 Operation. Makeup air systems serving solidfuel cooking operations shall be interlocked with the exhaust air system and powered, if necessary, to prevent the space from attaining a negative pressure while the solidfuel appliance is in operation. [NFPA 96:15.6.3]
517.7 Fire-Extinguishing Equipment for Solid-Fuel Cooking. Solid-fuel cooking appliances that produce greaseladen vapors shall be protected by listed fire-extinguishing equipment.
Exception: Where acceptable to the Authority Having Jurisdiction, solid-fuel cooking appliances constructed of solid masonry or reinforced Portland or refractory cement concrete and vented in accordance with NFPA 211 shall not require fixed automatic fire-extinguishing equipment. [NFPA 96:15.7.1, 15.7.2]
517.7.1 Grease Removal Devices, Hoods, and Duct Systems. Listed fire-extinguishing equipment shall be provided for the protection of grease removal devices, hoods, and duct systems. [NFPA 96:15.7.3]
Exception: Where acceptable to the Authority Having Jurisdiction, solid-fuel cooking appliances constructed of solid masonry or reinforced Portland or refractory cement concrete and vented in accordance with NFPA 211 shall
not require automatic fire-extinguishing equipment for the protection of grease removal devices, hoods, and duct systems. [NFPA 96:15.7.4]
517.7.2 Listed Fire-Extinguishing Equipment. Listed fire-extinguishing equipment for solid-fuel-burning cooking appliances, where required, shall comply with Section 513.0 and shall use water-based agents.
[NFPA 96:15.7.5] **517.7.3 Rating and Design.
CMC § 509.2.3 Medium relevance — show source text
509.2.3 Grease Filters. Grease filters shall be listed
and constructed of steel or other non-combustible material, and shall be of rigid construction that will not distort or crush under normal operation, handling, cleaning, or replacement. [SFM] For applications listed in Section 1.11.0 regulated by the Office of the State Fire Marshal, grease filters shall be Class I when tested in accordance with the test method in Title 24, Part 12, Chapter 12-71, SFM Standard 12-71-1.
509.2.3.1 Arrangement. Grease filters shall be arranged so that all exhaust air passes through the grease filters. [NFPA 96:6.2.3.4]
509.2.3.2 Accessibility. Grease filters shall be easily accessible for removal. [NFPA 96:6.2.3.5]
509.2.3.3 Angled Installation. Grease filters shall be installed at an angle not less than 45 degrees (0.79 rad) from the horizontal. [NFPA 96:6.2.3.6]
509.2.3.4 [DPH] Grease filters shall be Class I when tested in accordance with the test method in
SFM 12-71-1.
509.2.4 Grease Drip Trays. Grease filters shall be equipped with a grease drip tray beneath their lower edges. [NFPA 96:6.2.4.1]
509.2.4.1 Size and Pitch. Grease drip trays shall be kept to the minimum size needed to collect grease. Grease drip trays shall be pitched to drain into an enclosed metal container having a capacity not exceeding 1 gallon (4 L). [NFPA 96:6.2.4.2, 6.2.4.3]
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EXHAUST SYSTEMS
509.2.5 Grease Filter Orientation. Grease filters that require a specific orientation to drain grease shall be clearly so designated on the face of the filter as to be visible with the filter installed, or the hood or filter shall be constructed so that filters cannot be installed in the wrong orientation. [NFPA 96:6.2.5]
509.3 Solid-Fuel Grease Removal Devices. Where solid-fuel cooking equipment is provided with grease removal devices, these devices shall be in accordance with Section 517.0.
510.0 Exhaust Duct Systems.
510.1 General. Ducts shall not pass through fire walls.
[NFPA 96:7.1.1]
510.1.1 Fire Hazards. All ducts shall lead directly to the exterior of the building, so as not to unduly increase any fire hazard. [NFPA 96:7.1.2]
510.1.2 Interconnection. Duct systems shall not be interconnected with any other building ventilation or exhaust system. [NFPA 96:7.1.3]
CMC § 507.4.1 Medium relevance — show source text
507.4.1 Listed. Where a hood, duct, or grease removal device is listed for clearances less than those required in Section 507.4, the listing requirements shall be permitted. [NFPA 96:4.2.2]
507.4.2 Clearance Reduction. Where a clearance reduction system consisting of 0.013 of an inch (0.33 mm) (28 gauge) sheet metal spaced out 1 inch (25.4 mm) on noncombustible spacers is provided, there shall be a minimum of 9 inches (229 mm) clearance to combustible material. [NFPA 96:4.2.3.1]
507.4.2.1 Mineral Wool Batts or Ceramic Fiber Blanket. Where a clearance reduction system consisting of 0.027 of an inch (0.686 mm) (22 gauge) sheet metal on 1 inch (25.4 mm) mineral wool batts or ceramic fiber blanket reinforced with wire mesh or equivalent spaced 1 inch (25.4 mm) on noncombustible spacers is provided, there shall be a minimum of 3 inches (76 mm) clearance to combustible material. [NFPA 96:4.2.3.2]
507.4.2.2 Field-Applied Grease Duct Enclo- sure. Where a clearance reduction system consisting of a listed and labeled field-applied grease duct enclosure material, system, product, or method of construction specifically evaluated for such purpose in accordance with ASTM E2336, the required clearance shall be in accordance with the listing.
[NFPA 96:4.2.3.3]
507.4.2.3 Zero Clearance. Zero clearance to limited-combustible materials shall be permitted where protected by one of the following:
(1) Metal lath and plaster.
(2) Ceramic tile.
(3) Quarry tile.
(4) Other noncombustible materials or assembly of noncombustible materials that are listed for the purpose of reducing clearance.
(5) Other materials and products that are listed for the purpose of reducing clearance. [NFPA 96:4.2.3.4]
507.4.3 Clearance Integrity. In the event of damage, the material or product shall be repaired and restored to
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EXHAUST SYSTEMS
meet its intended listing or clearance requirements and shall be acceptable to the Authority Having Jurisdiction.
[NFPA 96:4.2.4.1]
507.4.3.1 Fire. In the event of a fire within a kitchen exhaust system, the duct and its enclosure (rated shaft, factory-built grease duct enclosure, or fieldapplied grease duct enclosure) shall be inspected by qualified personnel to determine whether the duct and protection method are structurally sound, capable of maintaining their fire protection function, and in compliance with this chapter for continued operation. [NFPA 96:4.2.4.2]
507.4.3.2 Required Protection. Protection shall be provided on the wall from the bottom of the hood to the floor, or to the top of the noncombustible material extending to the floor, to the same level as required in Section 507.4. [NFPA 96:4.2.4.3]
CMC § 2.5 Medium relevance — show source text
(7) A fire suppression system nozzle(s) shall be installed to protect the solid fuel holder.
(8) The fire suppression system shall be designed and installed to protect the entire cooking operation.
(9) Each solid fuel holder shall be limited to a size of 150 cubic inches (2.5 L), with no dimension to exceed 20 inches (508 mm).
(10) A maximum of one solid fuel holder for each 100 000 Btu/h (29 kW), or portion thereof, of burner capacity shall be permitted.
(11) Solid fuel shall be immersed in water for a continuous period of at least 24 hours immediately prior to being placed in the cooking equipment.
(12) The inspection frequency shall be the same as for solid fuel cooking operations in Table 514.3.
[NFPA 96:15.3.4] 517.4 Exhaust Systems for Solid-Fuel Cooking. Where a hood is not required, in buildings where the duct system is three stories or less in height, a duct complying with Section 510.0 shall be provided. [NFPA 96:15.4] 517.4.1 Hood. If a hood is used in buildings where the duct system is three stories or less in height, the duct system shall comply with Section 510.0. [NFPA 96:15.4.1] 517.4.2 Building Exceeding Four Stories. A listed or approved grease duct system that is four stories in height or greater shall be provided for solid-fuel cooking exhaust systems. [NFPA 96:15.4.2]
517.4.3 Prohibited. Wall terminations of solid-fuel exhaust systems shall be prohibited. [NFPA 96:15.4.4]
517.5 Grease Removal Devices for Solid-Fuel Cook- ing. Grease removal devices shall be constructed of steel or stainless steel or be approved for solid-fuel cooking. [NFPA 96:15.5.1] 517.5.1 Spark Arrester Devices. If airborne sparks and embers can be generated by the solid fuel cooking operation, spark arrester devices shall be used prior to using the grease removal device, to minimize the entrance of these sparks and embers into the grease removal device and into the hood and the duct system. [NFPA 96:15.5.2] 517.5.2 Filters. Filters shall be a minimum of 4 feet (1219 mm) above the appliance cooking surface. [NFPA 96:15.5.3] 517.6 Air Movement for Solid-Fuel Cooking. Exhaust system requirements shall comply with Section 511.0 for hooded operation or shall be installed in accordance with the manufacturer’s recommendations for unhooded applications.
[NFPA 96:15.6.1]
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EXHAUST SYSTEMS
517.6.1 Replacement Air. A replacement or makeup air system shall be provided to ensure a positive supply of replacement air at all times during cooking operations.
[NFPA 96:15.6.2]
CMC § 509.2.4.1 Medium relevance — show source text
509.2.4.1 Size and Pitch. Grease drip trays shall be kept to the minimum size needed to collect grease. Grease drip trays shall be pitched to drain into an enclosed metal container having a capacity not exceeding 1 gallon (4 L). [NFPA 96:6.2.4.2, 6.2.4.3]
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EXHAUST SYSTEMS
509.2.5 Grease Filter Orientation. Grease filters that require a specific orientation to drain grease shall be clearly so designated on the face of the filter as to be visible with the filter installed, or the hood or filter shall be constructed so that filters cannot be installed in the wrong orientation. [NFPA 96:6.2.5]
509.3 Solid-Fuel Grease Removal Devices. Where solid-fuel cooking equipment is provided with grease removal devices, these devices shall be in accordance with Section 517.0.
510.0 Exhaust Duct Systems.
510.1 General. Ducts shall not pass through fire walls.
[NFPA 96:7.1.1]
510.1.1 Fire Hazards. All ducts shall lead directly to the exterior of the building, so as not to unduly increase any fire hazard. [NFPA 96:7.1.2]
510.1.2 Interconnection. Duct systems shall not be interconnected with any other building ventilation or exhaust system. [NFPA 96:7.1.3]
510.1.3 Duct Installation. All ducts shall be installed with a minimum slope of ¼ inch per linear foot (20.8 mm/m) on horizontal runs up to 75 feet (22 860 mm) and a minimum slope of 1 inch per linear foot (83.2 mm/m) on horizontal runs greater than 75 feet (22 860 mm). Factory-built grease ducts shall be permitted to be installed at a lesser slope in accordance with the listing and the manufacturer’s instructions. All horizontal ducts shall be provided with access in accordance with Section 510.3.3.
Drains shall be provided at low points in horizontal ducts. Where provided, drains shall be continuously welded to the exhaust duct or in accordance with the terms of the listing and the manufacturer’s installation manual.
All ducts shall be installed without forming dips or traps. In manifold (common duct) systems, the lowest end of the main duct shall be connected flush on the bottom with the branch duct. [NFPA 96:7.1.5 – 7.1.5.5]
510.1.4 Accessibility. Openings required for accessibility shall comply with Section 510.3 through Section 510.3.2. [NFPA 96:7.1.6]
510.1.5 Sign. A sign stating the following shall be placed on all access panels:
ACCESS PANEL – DO NOT OBSTRUCT [NFPA 96:7.1.7]
CMC § 0.06 Medium relevance — show source text
For SI units: 1 inch = 25 mm, 1 gallon per minute = 0.06 L/s
Notes: 1 For interceptor sizing by the fixture capacity see the example below. 2 1 ∕ 4 inch slope per foot (20.8 mm/m) based on Manning’s formula with friction factor N = 0.012.
EXAMPLE 1014.2.1
SIZING HYDROMECHANICAL GREASE INTERCEPTOR(S)
USING FIXTURE CAPACITY
Step 1: Determine the flow rate from each fixture.
[Length] X [Width] X [Depth] / [231] = Gallons X [0.75 fill factor] / [Drain
Period (1 minute or 2 minutes)]
Step 2: Calculate the total load from fixtures that discharge into
the interceptor.
FIXTURES COMPART-
MENTSLOAD
(gallons)SIZE OF
GREASE
INTERCEPTOR
ONE-MINUTE
DRAINAGE
PERIOD
(gpm)TWO-
MINUTE
DRAINAGE
PERIOD
(gpm)
Compartment
size–– –– –– ––
24 inches x 24
inches x 12
inches2 44.9 –– ––
Hydrant–– 3 –– ––
Rated
Appliance–– 2 –– ––
–––– 49.9 50 25 For SI units: 1 inch = 25.4 mm, 1 gallon per minute = 0.06 L/s, 1 gallon =
3.785 L
1014.3 Gravity Grease Interceptors. Required gravity grease interceptors shall comply with the provisions of Section 1014.3.1 through Section 1014.3.7.
1014.3.1 General. The provisions of this section shall apply to the design, construction, installation, and testing of commercial kitchen gravity grease interceptors.
1014.3.2 Waste Discharge Requirements. Waste discharge in establishments from fixtures and equipment
For SI units: 1 inch = 25.4 mm, 1 gallon per minute = 0.06 L/s, 1 gallon =
3.785 L
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TRAPS AND INTERCEPTORS
which contain grease, including but not limited to, scullery sinks, pot and pan sinks, dishwashers, soup kettles, and floor drains located in areas where grease-containing materials exist, shall be permitted to be drained into the sanitary waste through the interceptor where approved by the Authority Having Jurisdiction.
1014.3.2.1 Toilets and Urinals. Toilets, urinals, and other similar fixtures shall not drain through the interceptor.
1014.3.2.2 Inlet Pipe. Waste shall enter the interceptor through the inlet pipe.
1014.3.3 Design. Gravity interceptors shall be constructed in accordance with the applicable standard in Chapter 17 or the design approved by the Authority Having Jurisdiction.
Frequently asked questions
What is the single most important thing to get right?
Use listed grease removal devices and maintain required clearances — or use a listed enclosure that explicitly states the reduced clearance it provides. § 509.1; § 507.4.6.3
Can I use mesh grease filters?
Not unless the mesh filter is evaluated as an integral part of a listed exhaust hood or listed in conjunction with a primary filter per UL 1046. § 509.1.1
How close can a grease duct be to a combustible wall?
Default is 18 inches (457 mm) clearance; reduced clearances are only permitted by an approved/listed reduction system or enclosure. § 507.4; § 507.4.1
What if I have a solid‑fuel charbroiler?
Grease filters must be at least 4 feet (1219 mm) above the cooking surface, and grease removal devices must meet solid‑fuel device rules in Section 517.0. § 509.2.1; § 509.3; § 517.5
Do I have to follow manufacturer instructions?
Yes. Listed hood/grease filter products are installed per their listings and the manufacturer’s instructions; listed products may specify reduced separation distances. § 509.2 Exception (3); § 507.4.1
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