Chapter 5 Hoods

Question 1

5.1.1

Answer 1

The hood or that portion of a primary collection means designed for collecting cooking vapors and residues shall be constructed of and be supported by steel not less than 0.048 inches (No. 18 MSG) in thickness, stainless steel not less than 0.036 (No. 20 MSG) in thickness, or other approved material of equivalent strength and fire and corrosion resistance.

Question 2

5.1.2

Answer 2

All seams, joints, penetrations of the hood enclosure that direct and capture grease-laden vapors and exhaust gases shall have a liquid tight continuous external weld to the hood’s lowers outermost perimeter.

Question 3

5.1.3

Answer 3

Seams, joints, and penetrations of the hood shall be permitted to be internally welded, provided that the weld is formed or ground smooth, so as to not trap grease, and is cleanable.

Question 4

5.1.4

Answer 4

Internal joints, seams, filter support frames, and fixtures within the hood enclosure do not need to be continuously welded but must be smooth and easily cleanable.

Question 5

5.1.12

Answer 5

Devices that require penetration of the hood, such as pipe and conduit penetration fittings and fasteners, shall be listed in accordance with ANSI/UL 1978.

Note: When a hood is penetrated for items, such as fire-extinguishing systems piping, the penetrations must be sealed with listed devices that can provide the same integrity as the hood. During the initial design and installation process, this can easily be identified and provided. Sealing penetrations that are made later on in the life of the system cannot be overlooked. Penetrations compromise the ability of the hood to capture grease-laden vapors and to contain a fire, and whenever a penetration is needed it must be properly sealed.

Question 6

5.1.13

Answer 6

Wall-mounted exhaust hood assemblies shall be tight against the back wall so as not to permit passage of grease vapor behind the hood or between the back wall and the hood assembly.

Question 7

5.2 Hood Size

Answer 7

Hoods shall be sized and configured to provide for the capture and removal of grease-laden vapors. The hood size is determined by the front and side overhang requirements form the hood to the cooking appliance, which are dimensions F (Front) (measured from front of the cooking surface not the appliance) and S (Side) in Exhibit 5.7(a) and Exhibit 5.7(b). Most listed hoods have many different listed overhang dimensions based on the type of cooking appliance under the hood. For example, the hood listing might call for 12 inch for dimension F when the hood is over a charbroiler, 9 inches when over a griddle, and only 6 inches when over a convection oven. One important difference between the nonlisted and the listed hood is that the listed hood “F” dimension is measured from the front of the cooking surface, not the front of the cooking appliance.

Question 8

5.4.1

Answer 8

Listed hood assemblies shall be installed in accordance with the terms of their listing and the manufacturer’s instructions.

Question 9

5.4.2

Answer 9

Listed hood assemblies shall be tested in accordance with UL 710 or equivalent.

Question 10

5.5 Listed Ultraviolet Hoods

Answer 10

Listed hoods shall be installed and maintained in accordance with the terms of their listing and the manufactures instructions.

Question 11

5.5.1

Answer 11

Duct systems connected to ultraviolet hoods shall comply with Chapter 7.

Question 12

5.5.2

Answer 12

Ultraviolet hoods shall be tested and listed in accordance with UL 710 and UL 710C.