Max size typeI hood with single exhaust duct or fan

[retire09]

Is there a maximum length or size of type I hood that can be served by a single exhaust duct and fan?

Is there a maximum distance from the most remote corner of the hood to the exhaust opening?

 

[hlfireinspector]

Is the Hood listed?

507.15 Exhaust outlets. Exhaust outlets located within thehood shall be located so as to optimize the capture of particulatematter. Each outlet shall serve not more than a 12-foot(3658 mm) section of hood.

​

Exhaust outlets in a hood are the openings to whichexhaust ducts connect and, depending on the size ofthe hood, more than one outlet might be needed. Theexhaust outlets are distributed in the hood to result inuniform exhaust flow rates over the entire hood openingarea. The 12-foot (3568 mm) limitation is intendedto prevent widely varying exhaust flow rates within thehood opening area by requiring multiple outlets onlarge (long) hoods.

​

 

[Darren Emery]

2009 IMC 507.15 Exhaust outlets. Exhaust outlets located within the hood shall be located so as to optimize the capture of particulate matter. Each outlet shall serve not more than an 12-foot section of hood.

 

[Dr. J]

"Is there a maximum length or size of type I hood that can be served by a single exhaust duct and fan?" - Not by the code, perhaps by the listing (if listed). There is a practical limit that can affect the code-required vapor capture: If you are sucking from just one end of a very long hood that has multiple collars, it is difficult to properly balance the flows between the close and far-away collars. Similar for a large hood has only one collar.

"Is there a maximum distance from the most remote corner of the hood to the exhaust opening?" - The above replies are for a non-listed hood. For a listed hood, follow the listing. It is possible (although unlikely) that a listed hood could have more than 12' per section if the manufacture got the proper capture.

 

[RJJ]

I agree with Dr.J it would have to be listed and labeled.

 

[fireguy]

If the exhaust system is listed, you can save money because the listed fan can draw about 30% less air than using non-listed components.