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Chapter 5 — EXHAUST SYSTEMS

506.1 Materials. Materials used in product-conveying duct

California Mechanical Code (Title 24, Part 4) · 2025 edition · updated 2026-09-10 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

systems shall be suitable for the intended use and shall be of rigid sheet metal.

Exceptions:

(1) Asbestos-cement, concrete, clay, or ceramic materials shall be permitted to be used where it is shown that these materials will be equivalent to metal ducts installed in accordance with this chapter.

(2) Ducts serving a Class 5 system shall be permitted to be constructed of approved nonmetallic material where the corrosive characteristics of the material being conveyed make a metal system unsuitable and where the mixture being conveyed is nonflammable.

Approved nonmetallic material shall be either a listed product having a flame-spread index not exceeding 25 and a smoke-developed rating of 50 or less on both inside and outside surfaces without evidence of continued progressive combustion, or shall have a flame-spread index not exceeding 25 and shall be installed with an automatic fire-sprinkler protection system inside the duct.

(3) Ducts used in central vacuum cleaning systems within a dwelling unit shall be constructed of materials in accordance with ASTM F2158 or the applicable standards referenced in Chapter 18. Penetrations of fire walls or floor-ceiling or roof-ceiling assemblies shall be in accordance with the building code.

Copper or ferrous pipes or conduits extending from within the separation between a garage and dwelling unit to the central vacuuming unit shall be permitted to be used.

TABLE 505.9 RANGE OF MINIMUM DUCT DESIGN VELOCITIES [1] {NFPA 91: TABLE A.4.2.5}

NATURE OF CONTAMINANTS EXAMPLES DESIGN VELOCITY
(feet per minute)
Vapors, gases, smoke All vapors, gases, and smoke 1000 - 20002
Fumes Welding 2000 - 2500
Very fine light dust Cotton lint, wood flour, litho powder 2500 - 3000
Dry dusts and powders Fine rubber dust, molding powder dust, jute lint, cotton dust, shavings (light), soap
dust, leather shavings		 3000 - 4000
Average industrial dusts Grinding dust, buffing lint (dry), wool jute dust (shaker waste), coffee beans, shoe dust,
granite dust, silica flour, general material handling, brick cutting, clay dust, foundry
(general), limestone dust, packaging and weighing asbestos dust in textile industries		 3500 - 4000
Heavy dusts Sawdust (heavy and wet), metal turnings, foundry tumbling barrels and shake-out,
sandblast dust, wood blocks, hog waste, brass turning, cast-iron boring dust, lead dust		 4000 - 4500
Heavy or moist dusts Lead dust with chips, moist cement dust, asbestos chunks from transite pipe cutting
machines, buffing lint (sticky), quick-lime dust		 4500 and up

For SI units: 1 foot per minute = 0.005 m/s Notes: 1 Systems that are handling combustible particulate solids shall be in accordance with NFPA 654. 2 Any desired velocity (economic optimum velocity usually within this range).

EXHAUST SYSTEMS

TABLE 506.2(1) MINIMUM SHEET METAL THICKNESS FOR ROUND DUCTS
NEGATIVE
PRESSURE
(inches
water
column)
REINF.
SPACING
(inches)		 CLASS 1
(inches)		 CLASS 1
(inches)		 CLASS 1
(inches)		 CLASS 1
(inches)		 CLASS 1
(inches)		 CLASS 1
(inches)		 CLASS 1
(inches)		 CLASS 1
(inches)		 CLASS 1
(inches)
NEGATIVE
PRESSURE
(inches
water
column)
REINF.
SPACING
(inches)		 Up to 7 8 to 11 12 to 15 16 to 19 20 to 23 24 to 35 36 to 47 48 to 59 60
To 7 0 0.021 (24 ga.) 0.021 (24 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.127 (10 ga.) –– ––
To 7 96 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.)
To 7 48 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.055 (16 ga.)
To 7 24 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.044 (18 ga.)
8 to 11 0 0.021 (24 ga.) 0.027 (22 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.097 (12 ga.) –– –– ––
8 to 11 96 0.021 (24 ga.) 0.027 (22 ga.) 0.027 (22 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.097 (12 ga.)
8 to 11 48 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.)
8 to 11 24 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.027 (22 ga.) 0.027 (22 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.)
12 to 15 0 0.021 (24 ga.) 0.033 (20 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.097 (12 ga.) –– –– ––
12 to 15 96 0.021 (24 ga.) 0.027 (22 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.097 (12 ga.) 0.112 (11 ga.) 0.112 (11 ga.)
12 to 15 48 0.021 (24 ga.) 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.097 (12 ga.)
12 to 15 24 0.021 (24 ga.) 0.021 (24 ga.) 0.021 (24 ga.) 0.027 (22 ga.) 0.027 (22 ga.) 0.027 (22 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.)
16 to 20 0 0.021 (24 ga.) 0.044 (18 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.112 (11 ga.) –– –– –– ––
16 to 20 96 0.021 (24 ga.) 0.033 (20 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.112 (11 ga.) 0.112 (11 ga.) 0.112 (11 ga.)
16 to 20 48 0.021 (24 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.112 (11 ga.)
16 to 20 24 0.021 (24 ga.) 0.021 (24 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.097 (12 ga.)
CLASS 2
(inches)		 CLASS 2
(inches)		 CLASS 2
(inches)		 CLASS 2
(inches)		 CLASS 2
(inches)		 CLASS 2
(inches)		 CLASS 2
(inches)		 CLASS 2
(inches)		 CLASS 2
(inches)
To 7 0 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.127 (10 ga.) –– ––
To 7 96 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.)
To 7 48 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.)
To 7 24 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.)
8 to 11 0 0.027 (22 ga.) 0.027 (22 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.097 (12 ga.) –– –– ––
8 to 11 96 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.097 (12 ga.)
8 to 11 48 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.)
8 to 11 24 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.)
12 to 15 0 0.027 (22 ga.) 0.033 (20 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.097 (12 ga.) –– –– ––
12 to 15 96 0.027 (22 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.097 (12 ga.) 0.112 (11 ga.) 0.112 (11 ga.)
12 to 15 48 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.097 (12 ga.)
12 to 15 24 0.027 (22 ga.) 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.)
16 to 20 0 0.027 (22 ga.) 0.044 (18 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.112 (11 ga.) –– –– –– ––
16 to 20 96 0.027 (22 ga.) 0.033 (20 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.112 (11 ga.) 0.112 (11 ga.) 0.112 (11 ga.)
16 to 20 48 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.097 (12 ga.)
16 to 20 24 0.027 (22 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.)
CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)
To 7 0 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.127 (10 ga.) –– ––
To 7 96 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.068 (14 ga.)
TABLE 506.2(1) MINIMUM SHEET METAL THICKNESS FOR ROUND DUCTS
To 7 48 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.068 (14 ga.)
To 7 24 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.068 (14 ga.)
8 to 11 0 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.097 (12 ga.) –– –– ––
8 to 11 96 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.097 (12 ga.)
8 to 11 48 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.068 (14 ga.)
8 to 11 24 0.033 (20 ga.) 0.033 (20 ga.) 0.044 (18 ga.) 0.044 (18 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.068 (14 ga.)

104 2025 CALIFORNIA MECHANICAL CODE

EXHAUST SYSTEMS

TABLE 506.2(1) (continued) MINIMUM SHEET METAL THICKNESS FOR ROUND DUCTS
NEGATIVE
PRESSURE
(inches
water
column)		 REINF.
SPACING
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)		 CLASS 3
(inches)
NEGATIVE
PRESSURE
(inches
water
column)		 REINF.
SPACING
(inches)		 Up to 7 8 to 11 12 to 15 16 to 19 20 to 23 24 to 35 36 to 47 48 to 59 60
12 to 15 0 0.133 (20 ga.) 0.133 (20 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.197 (12 ga.) –– –– ––
12 to 15 96 0.133 (20 ga.) 0.133 (20 ga.) 0.144 (18 ga.) 0.144 (18 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.197 (12 ga.) 0.112 (11 ga.) 0.112 (11 ga.)
12 to 15 48 0.133 (20 ga.) 0.133 (20 ga.) 0.144 (18 ga.) 0.144 (18 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.168 (14 ga.)
12 to 15 24 0.133 (20 ga.) 0.133 (20 ga.) 0.144 (18 ga.) 0.144 (18 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.168 (14 ga.)
16 to 20 0 0.133 (20 ga.) 0.144 (18 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.112 (11 ga.) –– –– –– ––
16 to 20 96 0.133 (20 ga.) 0.133 (20 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.112 (11 ga.) 0.112 (11 ga.) 0.112 (11 ga.)
16 to 20 48 0.133 (20 ga.) 0.133 (20 ga.) 0.144 (18 ga.) 0.144 (18 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.197 (12 ga.)
16 to 20 24 0.133 (20 ga.) 0.133 (20 ga.) 0.144 (18 ga.) 0.144 (18 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.168 (14 ga.)
CLASS 4
(inches)		 CLASS 4
(inches)		 CLASS 4
(inches)		 CLASS 4
(inches)		 CLASS 4
(inches)		 CLASS 4
(inches)		 CLASS 4
(inches)		 CLASS 4
(inches)		 CLASS 4
(inches)
To 7 0 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) –– ––
To 7 96 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.197 (12 ga.) 0.197 (12 ga.)
To 7 48 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.197 (12 ga.) 0.197 (12 ga.)
To 7 24 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.197 (12 ga.) 0.197 (12 ga.)
8 to 11 0 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.197 (12 ga.) –– –– ––
8 to 11 96 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.197 (12 ga.) 0.197 (12 ga.)
8 to 11 48 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.197 (12 ga.) 0.197 (12 ga.)
8 to 11 24 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.197 (12 ga.) 0.197 (12 ga.)
12 to 15 0 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.197 (12 ga.) –– –– ––
12 to 15 96 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.112 (11 ga.) 0.112 (11 ga.)
12 to 15 48 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.155 (16 ga.) 0.168 (14 ga.) 0.168 (14 ga.) 0.197 (12 ga.) 0.197 (12 ga.) 0.097 (12 ga.)
12 to 15 24 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.097 (12 ga.) 0.097 (12 ga.)
16 to 20 0 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.112 (11 ga.) –– –– –– ––
16 to 20 96 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.112 (11 ga.) 0.112 (11 ga.) 0.112 (11 ga.)
16 to 20 48 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.097 (12 ga.) 0.097 (12 ga.)
16 to 20 24 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.055 (16 ga.) 0.068 (14 ga.) 0.068 (14 ga.) 0.097 (12 ga.) 0.097 (12 ga.) 0.097 (12 ga.)

For SI units: 1 inch = 25.4 mm, 1 inch water column = 0.249 kPa

Aluminum ducts shall not be used in systems conveying flammable vapors, fumes, or explosive dusts, nor in Class 2, 3, or 4 systems. Galvanized steel and aluminum ducts shall not be used where the temperature of the material being conveyed exceeds 400°F (204°C). Metal ducts used in Class 5 systems that are not resistant to the corrosiveness of the product shall be protected with an approved corrosion-resistant material.

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▸Contents — California Mechanical Code (Title 24, Part 4)
California Mechanical Code (Title 24, Part 4)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — VENTILATION AIR
  5. ▸Chapter 5 — EXHAUST SYSTEMS
    Overview
    1. 503.1 General. Motors and fans shall be sized to provide
    2. 503.2 Fans. Parts of fans in contact with explosive or flammab…
    3. 504.1 General. Where not specified in this chapter, exhaust
    4. 501.1 Applicability. This chapter includes requirements for
    5. 502.1 Exhaust Opening Protection. Exhaust openings
    6. 502.2 Termination of Exhaust Ducts. Exhaust ducts
    7. 504.2 Independent Exhaust Systems. Single or combined mechanic…
    8. 504.3 Domestic Cooking Exhaust Equipment.
    9. 504.4 Clothes Dryers. A clothes dryer exhaust duct shall
    10. 504.5 Heat Recovery Ventilation (HRV) and Energy
    11. 505.1 General. A mechanical ventilation or exhaust system
    12. 505.2 Incompatible Materials. Incompatible materials
    13. 505.3 Flammability Limit. Unless the circumstances stipulated …
    14. 505.4 Air-Moving Devices. Air-moving devices shall be
    15. 505.5 Generating Flames, Sparks, or Hot Materials.
    16. 505.6 Fire Dampers. Fire dampers shall be permitted to be
    17. 505.7 Fire Detection, Smoke Control, and Alarm Sys-
    18. 505.8 Product-Conveying Duct Classifications. Product-conveyin…
    19. 505.9 Minimum Velocities and Circulation. The velocity and cir…
    20. 505.10 Makeup Air. Makeup air shall be provided to replenish a…
    21. 505.11 Hoods and Enclosures. Hoods and enclosures shall
    22. 505.12 Pharmacies – Compounding Area of Par-
    23. 506.1 Materials. Materials used in product-conveying duct
    24. 506.2 Construction. Ducts used for conveying products
    25. 506.3 Penetrations. Exhaust ducts shall not pass through
    26. 506.4 Condensate. Joints in duct construction shall be liquidt…
    27. 506.5 Fittings. Fittings in Class 2, 3, and 4 systems shall be
    28. 506.6 Explosion Venting. Ducts conveying explosive dusts
    29. 506.7 Supports. Supports shall be of noncombustible materials,…
    30. 506.8 Fire Protection. Sprinklers or other fire-protection
    31. 506.9 Protection from Physical Damage. Ducts and
    32. 506.10 Duct Clearances. Unless the conditions stipulated
    33. 506.11 Clearance Reduction Methods. It shall be permitted to p…
    34. 507.1 Exhaust Systems. Exhaust systems serving Type I
    35. 507.2 Type I Hood Exhaust System Requirements.
    36. 507.3 Listed Devices. Penetrations shall be sealed with
    37. 507.4 Clearance. Where enclosures are not required, hoods,
    38. 507.5 Drawings. For cooking operations in buildings, a
    39. 507.6 Notification of Change. If required by the Authority Hav…
    40. 507.7 Pharmaceutical Compounding Exhaust Dis-
    41. 508.1 Where Required. Type I hoods shall be installed at
    42. 508.2 Listed Type I Hood Assemblies. Listed hood
    43. 508.3 Construction of Type I Hoods. The hood or that
    44. 508.4 Supports. Hoods shall be secured in place to resist
    45. 508.5 Hood Size. Hoods shall be sized in accordance with
    46. 508.6 Solid-Fuel Hood Assemblies. Where solid-fuel
    47. 508.7 Exhaust Outlets. An exhaust outlet within an
    48. 509.1 Grease Removal Devices. Listed grease filters or
    49. 509.2 Installation. The distance between the grease removal
    50. 509.3 Solid-Fuel Grease Removal Devices. Where
    51. 510.1 General. Ducts shall not pass through fire walls.
    52. 510.2 Clearance. Clearance between ducts and combustible
    53. 510.3 Openings. Openings shall be provided at the sides or
    54. 510.4 Listed Grease Ducts. Listed grease ducts shall be
    55. 510.5 Other Grease Ducts. Other grease ducts shall comply with…
    56. 510.6 Exterior Installations. For cooking operations in
    57. 510.7 Interior Installations. In all buildings more than one
    58. 510.8 Underground Installations. Grease ducts installed
    59. 510.9 Termination of Type I Hood Exhaust System.
    60. 510.10 Solid-Fuel Duct Systems. Where solid-fuel cooking equip…
    61. 511.1 Exhaust Fans for Commercial Cooking Opera-
    62. 511.2 Airflow. The air velocity through a duct shall be not
    63. 511.3 Makeup Air. The makeup air quantity shall prevent
    64. 511.4 Common Duct (Manifold) Systems. Master
    65. 511.5 Solid-Fuel Air Movement Requirements. Where
    66. 512.1 Dampers. Dampers shall not be installed in exhaust
    67. 512.2 Electrical Equipment. Wiring systems of any type
    68. 512.3 Other Equipment. Fume incinerators, thermal recovery uni…
    69. 512.4 Solid-Fuel Auxiliary Equipment. Where solid fuel
    70. 513.1 General. Fire-extinguishing equipment for the protection…
    71. 513.2 Types of Equipment. Fire-extinguishing equipment
    72. 513.3 Simultaneous Operation. Fixed pipe extinguishing
    73. 513.4 Fuel and Electric Power Shutoff. Upon actuation of
    74. 513.5 Manual Actuation. All systems shall have both automatic …
    75. 513.6 System Annunciation. Upon actuation of an automatic fire…
    76. 513.7 Special Design and Application. Hoods containing
    77. 513.8 Review and Certification. Where required, complete
    78. 513.9 Installation Requirements. Installation of systems
    79. 513.10 Portable Fire Extinguishers. Portable fire extinguisher…
    80. 513.11 Maintenance. Portable fire extinguishers shall be
    81. 513.12 Solid-Fuel Fire-Extinguishing Equipment.
    82. 514.1 Operating Procedures. Exhaust systems shall be
    83. 514.2 Inspection, Testing, and Maintenance. Maintenance of the…
    84. 514.3 Inspection for Grease Buildup. The entire exhaust
    85. 514.4 Cleaning of Exhaust Systems. If, upon inspection,
    86. 514.5 Cooking Equipment Maintenance. Inspection and
    87. 515.1 Cooking Equipment. Cooking equipment shall be
    88. 515.2 Operating Controls. Deep-fat fryers shall be equipped
    89. 516.1 General Requirements. Recirculating systems containing o…
    90. 516.2 Design Restrictions. All recirculating systems shall
    91. 516.3 Interlocks. The recirculating system shall be provided
    92. 516.4 Location and Application Restrictions. The
    93. 516.5 Additional Fire Safety Requirements. In addition to the …
    94. 516.6 Use and Maintenance. Automatic or manual covers on cooki…
    95. 517.1 Venting Application. Venting requirements of solidfuel c…
    96. 517.2 Location of Appliances. For cooking operations in
    97. 517.3 Hoods for Solid-Fuel Cooking. Hoods shall be sized
    98. 517.4 Exhaust Systems for Solid-Fuel Cooking. Where
    99. 517.5 Grease Removal Devices for Solid-Fuel Cook-
    100. 517.6 Air Movement for Solid-Fuel Cooking. Exhaust
    101. 517.7 Fire-Extinguishing Equipment for Solid-Fuel
    102. 517.8 Other Safety Requirements. Metal-fabricated solidfuel co…
    103. 518.1 General. Downdraft appliance ventilation system
    104. 518.2 Ventilation System. The downdraft appliance ventilation …
    105. 518.3 Fire-Extinguishing Equipment. For fire-extinguishing equ…
    106. 518.4 Airflow Switch or Transducer. An airflow switch or
    107. 518.5 Surface Materials. Any surface located directly
    108. 519.1 Where Required. Type II hoods shall be installed
    109. 519.2 Construction of Type II Hoods. Type II hoods
    110. 519.3 Type II Hood Exhaust System Net Airflow. The
    111. 519.4 Type II Exhaust Duct Systems. Ducts and
    112. 519.5 Termination of Type II Hood Exhaust System.
    113. 519.6 Makeup Air. Makeup air shall be provided in accordance w…
    114. 519.7 Independent Exhaust Duct System. Single or
  6. Chapter 6 — DUCT SYSTEMS
  7. Chapter 7 — COMBUSTION AIR
  8. Chapter 8 — CHIMNEYS AND VENTS
  9. Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES
  10. Chapter 10 — BOILERS AND PRESSURE VESSELS
  11. Chapter 11 — REFRIGERATION
  12. Chapter 12 — HYDRONICS
  13. Chapter 13 — FUEL GAS PIPING
  14. Chapter 14 — PROCESS PIPING
  15. Chapter 15 — SOLAR ENERGY SYSTEMS
  16. Chapter 16 — STATIONARY POWER PLANTS
  17. Chapter 17 — GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE…
  18. Chapter 18 — REFERENCED STANDARDS
  19. Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
  20. Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
  21. Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
  22. Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
  23. Appendix E — SUSTAINABLE PRACTICES
  24. Appendix F — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
  25. Appendix G — EXAMPLE CALCULATION OF OUTDOOR AIR RATE
  26. Appendix H — PROFESSIONAL QUALIFICATIONS
  27. Appendix I — INDOOR HORTICULTURAL FACILITIES
  28. Appendix J — CLEAN AIR DELIVERY

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