NFPA 96 - Grease duct access size

[doopedeng]

Hi All,
I have a vertical grease duct serving commercial kitchen equipment that is 18x30 running up through 5 stories to the roof and wondered if that is too small to permit "personnel entry" for cleaning as per Section 7.4.2.1, Vertical Ducts in NFPA 96-2004, or elsewhere? I.e., will I need to install access hatches on each floor instead?

Thanks in advance.
Dooped

 

[Engineer6512]

If you look at section 7.4.1.1 it states for a horizontal opening, dimensions must be at least 20" x 20".

So for a vertical opening I would say at a minimum those dimensions should hold, but realistically even that might be too small to accomodate the equipment used to descend/acent the duct.

Since your minimum dimension is only 18" I would say that is too small and you should put an access door on each floor.

 

[fireguy519345]

My NFPA 96-2004 is in the van, and the van is loaded for the fire suppression system install tomorrow. I did get out my 1998 edition. to paraphrase parts of the 1998 standard, which are similar to 2004. Note the 2004 standard has been re-written and sections do not corrospond to 1998.

4-3.4.4 Acess panels shall be rated for 1500°F
Panels meeting NFPA 96 & UL are Flamegard.com and ductmate.com Others may meet the standards, these 2 I am familiar with. Don't forget to use listed access panels for the enclosure.

If access for personnel is desired, make sure the hole in the top is large enought for a person wearing a harness, and there is a frame to support that person as there are lowered into the hole.

If there is a large panel at the top of the shaft, that is what the hood cleaners will use. The 2004 calls for access panels every 10 or 12 feet, but probably will be used for inspection only. Access to the access panels will need to be furnished. Hood cleaning is normally done at night, when every other business is closed, so access can be difficult.

There are companies who specialize in cleaing duct systems such as yours. You might check the Yellow pages and contact a cleaning company doing large systems. I could furnish some names for you, but I doubt that is allowed on this board.

Fireguy

 

[doopedeng]

Thanks for your responses. My initial thought was that 18" was too small for personnel entry, so you've supported that assumption. It shouldn't be that hard for me to provide the access hatches on each floor, so we'll just add that to the expense of the project, I guess.

Thanks for all the info.

D