Dr. J
Silver Member
If anyone asks if they can connect what looks like a Type I hood (baffle filters, welded construction, etc) to regular non-welded duct because all that is under the hood are Type II appliances (soup kettles, steamers, etc), JUST SAY NO!
I recently did an investigation where half of the cooking line up was served by welded 16 ga, black iron duct, bolted and gasketed access doors, in a rated enclosure, etc. (code compliant Type I), and the other half was served by S&Drive galvanized duct, with standard flimsy duct access doors, turning vanes, and fire dampers where it enters and exits the shaft. Standing in the kitchen, you would not know there was a difference in the duct systems because all hoods are the same - listed Type I hoods. Apparently, 25 years ago, when it was first designed, one half was dedicated to Type I equipment, and the other was for Type II equipment. However, sometime between then and now, the cooking line up was re-arranged, and now the worst offenders (6 burner hot top and CHARBROILER!!!) are under the section served by the S&Drive duct. I don't blame the kitchen manager, they did not know any better (although the facility manager should have).
OMG - a video of that duct was done and the camera kept getting buried in the grease. Grease is leaking out of the joints. Grease is clogging up the turning vanes. As the camera was being pushed along, it created an avalanche of oozy grease. Oh yeah - they have been paying a hood cleaning company to "clean" the system. The plenum behind the filters is nice and shiny though.
I would cite 506.3.1 "Ducts serving Type I hoods shall be constructed of materials in accordance with Sections 506.3.1.1 and 506.3.1.2." The argument may be "But it is a Type II hood, there is no MAXIMUM construction requirement for a type II, this hood may exceed the Type II requirements, but is not illegal". Hopefully, there are not that many people out there buying an expensive Type I hood when they don't need to.
I recently did an investigation where half of the cooking line up was served by welded 16 ga, black iron duct, bolted and gasketed access doors, in a rated enclosure, etc. (code compliant Type I), and the other half was served by S&Drive galvanized duct, with standard flimsy duct access doors, turning vanes, and fire dampers where it enters and exits the shaft. Standing in the kitchen, you would not know there was a difference in the duct systems because all hoods are the same - listed Type I hoods. Apparently, 25 years ago, when it was first designed, one half was dedicated to Type I equipment, and the other was for Type II equipment. However, sometime between then and now, the cooking line up was re-arranged, and now the worst offenders (6 burner hot top and CHARBROILER!!!) are under the section served by the S&Drive duct. I don't blame the kitchen manager, they did not know any better (although the facility manager should have).
OMG - a video of that duct was done and the camera kept getting buried in the grease. Grease is leaking out of the joints. Grease is clogging up the turning vanes. As the camera was being pushed along, it created an avalanche of oozy grease. Oh yeah - they have been paying a hood cleaning company to "clean" the system. The plenum behind the filters is nice and shiny though.
I would cite 506.3.1 "Ducts serving Type I hoods shall be constructed of materials in accordance with Sections 506.3.1.1 and 506.3.1.2." The argument may be "But it is a Type II hood, there is no MAXIMUM construction requirement for a type II, this hood may exceed the Type II requirements, but is not illegal". Hopefully, there are not that many people out there buying an expensive Type I hood when they don't need to.