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Separate Grain Room?


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We're currently working with an architect to finish ironing out our floor plan. We plan to purchase local grain and mill ourselves with a hammermill. We have a flex-flow auger system for moving the grain afterward. They're stating that building a separate fire rated grain room is required for milling and storage. I can't recall seeing a separate room in any other distillery that I've visited.

I've searched through the IFC and IBC and looked at all of the MAQ tables. I just can't seem to find anything that is clear. I could understand the hammermill being separated because of the dust, but does the grain have to be separated while it is being stored before milling?

Could someone point me in the right direction of where I can find out a definite answer on this?

Thanks much!

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I am not an architect, engineer, and most certainly am not a lawyer.

Read up on the differences between NEC Class 1 and Class 2. In addition, if you have state variations of the IBC and IFC, search them for references to combustible dust being a trigger for high hazard (H2) occupancy. I've seen versions table 307 that list Combustible Dust as physical hazard. Lastly, review required fire rating between groups/occupancies/incidental use. Could be any number of things.

It's a stretch, but I'd also check your local codes for recs and guidance around how other high dust uses are handled (woodworking shops are sometimes very clearly spelled out).

I would say the typical argument is that you aren't generating enough dust to represent a hazard or that would require a separation.

You might want to check with your suppliers to see if they can provide cracked or milled grain. Run the numbers. What's the payback on the equipment, labor, maintenance, and construction costs? It might not be worth your time or money to mill.

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Thanks for your help, James! I did more research and have found a little more information. I'll attach it here for anyone else interested in digging through and reading it for themselves.

The IFC does not address this issue directly, rather it points to the NFPA to give guidance. From what I have found so far, the NFPA only requires grain to be separated if the grain storage area is greater than 5000 sq ft.

IFC Chp 22 - Combustible Dust Producing Procedures


2204.1 Standards.
The fire code official is authorized to enforce applicable provisions of the codes and standards listed in Table 2204.1 to prevent and control dust explosions.


NFPA 61 Agricultural and Food Products

NFPA 69 Explosion Prevention

NFPA 70 National Electrical Code

NFPA 85 Boiler and Combustion System Hazards

NFPA 120 Coal Preparation Plants

NFPA 484 Combustible Metals, Metal Powders and Metal Dusts

NFPA 654 Manufacturing, Processing and Handling of Combustible Particulate Solids

NFPA 655 Prevention of Sulfur Fires and Explosions

NFPA 664 Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities

NFPA - 61


4.3.1 - Interior Wall Construction

Storage areas larger than 5000 sq ft and containing packaging , bagging, palletizing, and pelleting equipment shall be cut off from all other areas with fire barrier walls designed for a minimum fire resistance of 2 hours and designed in accordance with NFPA 5000, Building Construction and Safety Code Chapter 8, Fire-Resistive Materials and Construction.

NFPA 654


This references testing the risks associated with combustible dust. I think this will come down to being able to convince your local authorities that the dust produced by your hammermill does not present a hazard.

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Lost Ark,

You may want to run this by your local fire inspector before you finalize you design and start building.

Point of fact, one of the most dangerous things you can do in a distillery is mill grain. Dust related explosions were directly spoken to during the safety track at ASCA during the conference last year. If you have the resources to do so, don't take this issue lightly.

From DISCUS Recommended Fire Protection Practices for Distilled Beverage Facilities:

For milling operations:

Process Occupancy guidelines:

Protect in accordance with NFPA 13 for Ordinary Hazard Group 2 occupancy (with a suggested minimum design area of 2000 ft2 (186 m2).

Electrical Area Classification:

Grain Handling




Equipment approved for use in Division 1or Zone 1 hazardous location is needed in all areas where grain dust can form a potentially explosive cloud, except those rooms or enclosures that have been specially purged, pressurized, or in some method separated from the dust hazard.



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My local fire inspector reviewing my high-level plans...

Boiler - yawn.

2K gal IB in barrels in the warehouse - double yawn.

"You going to be milling grain?" I say nope, pre-milled. Visible sigh of relief.

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Thanks guys. We're certainly not doing anything just yet. This is all in preparation before we sit down with the county and Fire Marshall. Our architects have never dealt with this, so we're educating them in a lot of areas. Our space already has a small "machine room" built out of block that would house our hammermill perfectly. Block is generally rated for 2 hours from what I can find. I just wanted to make sure that our unmilled grain storage did not also have to be in an enclosed and compartmentalized space. That would require us building a pretty large room which is expensive and take up precious space.

Appreciate all of the input!

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