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Malt milling and City Hall

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  • Malt milling and City Hall


    Does anyone know of any good resources that have been employed to soothe the concerns of anxious civic authorities when it comes to the question of malt milling? We're doing a 10 barrel brewery with a 2 roller Kunzl but you'd think we were building a napalm factory.


    Conrad Gmoser

  • #2
    Someone else will probably have a better answer for this, but I think a key is to show you aren't actually milling the grain, but crushing it. This may seem like semantics, but there is quite a difference between milling grain into flour and crushing grains for mashing.
    Pipeworks Brewing Company


    • #3
      Didn't the latest issue of The New Brewer have an article on that? Haven't had time to read it yet, just gave it a quick skim over. There you go, "Combustible Dust Hazards in the Brewery", The New Brewer, Jan/Feb 2013.

      Same issue here, 10bbl, 2 roller Engl. After reading some threads here (and inspection horror stories) we WAY over-engineered our mill area electricals in order to cut this possible problem off at the bud. Closed all the open sockets, NEMA explosion proof everything, etc.. Unfortunately, the L&I inspector showed up, saw the conduit and big ol' dust-proof Frankenstein switch, blanched, wrote us a citation saying we had to outline our "explosion hazard area" whatever that means. Being an inspector and not a human being, he refused to tell us what that meant or help us in any way. We tried to figure out if we had to meet some specific code, or have some expert take a look. No answers. So when he came back we told him there was no danger (which given our setup is true!) and he signed it of in two seconds without a thought. We were murderous.
      Russell Everett
      Co-Founder / Head Brewer
      Bainbridge Island Brewing
      Bainbridge Island, WA


      • #4
        It's a matter of the unknown...

        Having recently gone through this very same issue (and still working on a solution), here's the letter we sent to our fire marshal concerning their fears of us blowing up the entire state.

        So, after some research on our own, we have come up with a plan to address the potential explosive hazard of the Mill Room. According to OSHA paperwork (see attached) that we were able to find online, there are four key elements that must be in place, simultaneously, for the possibility of an explosion to occur.

        From Page 3 of the attached PDF (see "NC-OSHA-paper" attachment)...

        For a dust explosion to occur in a grain elevator or mill, the four following key elements must exist simultaneously:
        1. Grain dusts, as the primary fuel
        2. Oxygen
        3. An ignition source (see Table 2)
        4. A confined space

        Without any one of these four elements, according to OSHA, an explosion cannot happen. With further reading, on pg.3, the OSHA report defines the types of grains, and their explosive properties.

        The grains we would be using generally fall under the table with "Grain Dust, winter wheat, corn, oats."
        In this cell of the table, we see that the Lower Explosive Limit (in g/m3) is 55. This translates into 0.055 oz/ft3.

        We have adjusted the size of our mill room (reflected in the "layout-6000sqft-f-millroomspecs.jpg" attachment) to a much larger room that will also house grain bag storage.

        In the newly sized room, the square footage will be 160 with a ceiling height of 15 ft. This gives us nearly 2400 ft3 of space to help minimize the #4 key element of an explosive hazard, a confined space.

        With 2400 ft3 of space, this allows for roughly 9 lbs of grain dust to be suspended and permeate the air before reaching the LEL of the room for our particular grain dust.

        Also, you will notice that we have adjusted to location of the room to encompass one of the overhead doors. With a set plan of action in place, when milling grains, to mandate that this overhead door must be open when performing any milling or cleaning of the mill room, this, in theory, effectively changes the size of the room to well beyond the definition of a confined space. This should completely remove the #4 confined space requirement for creating an explosive environment. We also intend to affix a make-up air fan to the wall adjacent to the overhead door, to create positive air flow through the room and out the door to ensure that very minimal accumulation of settling dust can occur.

        Also, from the "NC-OSHA-paper" attachment, pg.3...
        "When dusts generated from grains are not properly handled, the conditions for an explosion can develop."

        This leads to a few key points to milling grains for a brewery setting that are different than milling grain for creating flour. The type of mill we will use is not the kind that creates copious amounts of dust. If our mill were to grind the grains into powder, we would be unable to brew. The mill used for brewing beer has a wide gap between it's rollers that simply cracks the grains and exposes the inner endosperm (please see attached jpg "cracked-grains" for an example of a what we are looking for in milling). If we were to crunch the grain much more than that, we would end up with a very thick flour mixture (think pancake batter) in our brewhouse, that would be impossible to create beer with. Our main goal in crushing grains in the mill room is to leave the outer husk as intact as possible, while still exposing the inner parts of the grain. The husk becomes a natural filter bed in the brewing process, while the inner endosperm becomes the carbohydrate and sugar soup that fermentable liquid is made from.
        Yes, cracking grains in a brewery mill does create some dust and flour, but it is minimized by the type of milling achieved. If we were milling down to a flour-like consistency, there would be a much higher likelihood of creating enough dust in the air to approach the OSHA LEL limits. The way we mill grains, along with a safe and standard cleaning regiment, will keep grain dust well below the amounts needed to cause an explosion hazard.
        Also, I would like to point out that brewery mills come equipped, standard, with UL listed explosion proof motors as well as magnetic trap systems to separate and prevent any ferrous object from entering the mill. This, along with explosion proof light fixtures, fans, and electrical wiring should remove the #3 required key element, an ignition source.

        I hope you see, and can agree, that with proper equipment, proper protocol, and a generously sized room, we can drastically reduce, and/or eliminate three of the four key elements that must be in place simultaneously to create an explosion hazard in our mill room. Thanks, and please let us know your thoughts in light of the new plan.
        The OSHA attachment I submitted can be found here, and the image of cracked grains is here.
        Alas, all that effort resulted in our fire marshal coming back to us saying that he understood what we were talking about, but couldn't give to OK for us to mill grains on-site without an "exhaustive and complete" review by a certified fire safety engineer. Funny thing is, he is certified as exactly that according to his e-mail signature. I think I can smell some double-dipping...
        Until we get this review, common sense and understanding isn't winning in our case, but I hope the information helps you, though! Keep me posted as you proceed. I'd love to hear how it works out for you in the end and any tips you get along the way may just help us, too.
        Jason Mullikin
        Head Brewer/Janitor/Wearer of many Hats
        Mully's Brewery
        141 Schooner Ln.
        Prince Frederick, MD


        • #5
          Anyone reading this thread and potentially going down this road remember: it's a malt crusher!
          Jamie Fulton
          Community Beer Co.
          Dallas, Texas

          "Beer for the Greater Good"


          • #6
            Thanks for the feedback so far. We did use the rather bland sounding 'Grain Handling' label on our drawings but that was enough to cause looks of consternation. We're just girding ourselves for comments from the building department and all the other fun departments who have an opportunity to get involved. I'll be sure to post some reports on our progress, however slow and excruciating it may me.

            I found the following image of a sieve analysis. It is from a Briess power point presentation called Practical Milling for the Craft Brewer.




            • #7
              Combustible dust... Opinion and Report?

              We too are experiencing quite a bit of harassment from our city officials and the building department. Here is a sample of what they are asking, oh and this is one of several emails they have sent me! My question is, have any of you worked with an engineer who is capable of writing a technical opinion and report on this matter? If so please let me know, thanks!

              Combustible dust exists as part of your proposed process. The remaining question is: Does the necessary mixes of factors exist which would cause us to classify the building or a portion thereof as a hazardous (H) occupancy. I am attaching a copy of the Dallas Building Code section which defines a “combustible dust.”

              We will need for you to submit to us a technical opinion and report. The opinion and report shall be prepared by a qualified engineer, specialist, laboratory or fire safety specialty organization acceptable to the building official and shall analyze the fire safety properties of the design, operation or use of the building or premises and the facilities and appurtenances situated thereon, to recommend necessary changes. The design submittal is to be prepared by, and bear the stamp of, a registered Texas engineer. Please be prepared to submit proper documentation indicating that the engineer has the appropriate background and experience to prepare such an analysis.

              The following is some information to give you an idea of the questions to be addressed.

              1. Determine the combustibility, explosive severity, and ignition sensitivity of dusts present in the facility. Knowing the explosion severity and ignition sensitivity will allow a determination to be made of the degree of hazard posed by the dusts present. It will also provide the data necessary for design of explosion suppression or venting systems and determine the degree of ignition source control required.

              2. Assess housekeeping in the facility and keep accumulations of dust to a minimum. Small layers of accumulated dust, if dispersed by an initiating event, are capable of producing large dust clouds of sufficient concentration to cause an explosion. Removal of dust accumulations can eliminate the risk of secondary explosions.

              3. Keep all processing equipment as tight as possible to prevent the escape of dust into the work environment. Keeping equipment tight will reduce the efforts needed in housekeeping.

              4. Assess the need for explosion protection in processing equipment. Processing equipment can contain standing or episodic dust clouds and is, often, not of sufficient strength to withstand a dust explosion. Adequate explosion protection will suppress, contain, or safely vent any explosion that occurs inside the equipment.

              5. Conduct a Hazardous Area Classification exercise of the facility. Electrical equipment is capable of igniting dust layers or clouds. A Hazardous Area Classification exercise will determine the degree of protection required for electrical installations in the facility.

              6. The implementation of a hot work permitting system. Hot work such as welding, flame cutting and grinding is capable of igniting dust layers or clouds. A hot work permitting system, if followed, will ensure that hot work is not conducted in areas unsafe for such activities.

              7. The implementation of a comprehensive preventive maintenance program to prevent and/or quickly identify equipment failures. Malfunctioning equipment is capable of generating sufficient heat to ignite dust layers or clouds.

              8. Is there a management of change process to prevent a change of conditions (increase or decrease the hazard)?

              9. Familiarize yourself with the requirements of NFPA 61 and NFPA 654. Additional activities may be required as determined by the technical report.

              Finally, if your assertion is that all of the above has been accounted for and your facility should not be classified as an H-occupancy, your assessment should include sufficient information to support this assertion. Moreover, the possible occupancy classifications as a non-hazardous occupancy will be a Group F, Division 1 or Group F, Division 2 classification. We will require specific documentation on your finished product indicating its percentage alcohol content in order to determine which division would be appropriate


              • #8

                Seriously? That's beyond ridiculous. They're also asking for the ABV of the finished product? Wtf? This is the city of Dallas building dept?
                Jamie Fulton
                Community Beer Co.
                Dallas, Texas

                "Beer for the Greater Good"


                • #9
                  I wish I was joking!


                  As far as I can tell, the reason they are asking for the ABV has to do with the Dallas Fire Code, apparently places that make beer above 12% would be considered F-1 MODERATELY HAZARDOUS, F -2 Low-hazard Occupancy hazard Occupancy includes 12% and below.

                  I am trying to figure out what all this means and how it will screw our plans up!


                  • #10
                    This is bizarre, but I wish I was surprised by anything the clowns at Dallas City Hall pull any more. If you manage to get this untangled, please let us know!
                    Cheers and beers,
                    Drew - BrainDead Brewing
                    Fighting ignorance and apathy since 2004.


                    • #11
                      RJA is probably the biggest firm in Dallas that does fire safety engineering but they are probably quite expensive and beyond the scope of your needs. My thought is to send an email to the local chapter of the society of fire preventing engineers and ask if they can refer you to somebody. You can reach them at Not sure if their members would be the right people to reach but I would imagine their members would know somebody.
                      DFW Employment Lawyer


                      • #12
                        As was said, it is a malt cracker not a mill. It is all in the wording. Mills make powder, crackers/crushers make smaller pieces.
                        Joel Halbleib
                        Partner / Zymurgist
                        Hive and Barrel Meadery
                        6302 Old La Grange Rd
                        Crestwood, KY


                        • #13
                          Another Dallas Brewer...

                          Drew and I chatted about this today and I remembered this thread, so I'll share our experience.

                          For the Brewpub in Dallas that we're starting we decided to use pre milled grain for now, it's really not what we want to do but it has it's advantages besides being safer in the eyes of our inspectors. I had decided this before the City even asked me, which they did as our construction blueprints were making the rounds in the permitting office. They asked for a letter from the head brewer on how we're going to handle our milling operations. So I whipped up a letter that outlined our plan for using pre milled malt from specific vendors as well as our storage plan and cleaning schedule, (even if you're not milling they were still worried about accumulated dust from handling). After I produced that letter they haven't brought it up again, we're a few months away from opening so I'm not sure if it'll come up again or not.

                          Honestly, I would love to mill our own as soon as possible but I'm not going to let the biz get held up by something like this.

                          I wonder if any inspectors ever read probrewer?


                          • #14
                            Opening soon in DFW

                            Aaron - are you guys still buying pre-milled malt?

                            We are considering wet milling, which I figure would drastically cut down on the "smaller" pieces left behind by "crushing." But what about the dust from pouring the malt before it hits water? And what if we don't wet mill?

                            I'm meeting with the GC and the inspector on Monday, and wanted to see if anybody else has recommendations on how to cut down their definition of a hazardous environment or help navigate through their concerns? Right now they are considering calling us Class III which I'm not sure what that means from a cost and manufacturing perspective, but the definition relies on "Division 1: Easily ignitable fibers or materials producing combustible flyings are handled, manufactured or used; Division 2: Easily ignitable fibers are stored or handled, other than in the process of manufacture." Class II doesn't seem too good either, including combustible dust in lieu of fibers.


                            • #15
                              Wake up!

                              Quit playing with semantics and realize you have a significant hazard of dust explosion in your milling room! If your milling room is absolutely dust free, sure, you're safe, but you're not living on the same planet as the rest of us.

                              The primary source of ignition in the majority of dust explosions is static electricity. Grain moving through a plastic pipe can generate thousands of volts of static potential, capable of producing a nice, fat spark. We had an employee using an ungrounded canister vacuum in the mill room get knocked off her feet by a static discharge from the vacuum hose.

                              The easiest way to deal with dust in the mill room is to seal all sources of dust--anywhere grain is moving, pre- or post-mill, then use a wood shop-style dust collection system to remove the dust and create a negative-pressure environment so no dust can escape. We assembled such a collection system for around $1,000 w/installation, and it totally satisfied OSHA and our local inspectors, and brought me a great deal of peace of mind.

                              If I can find the post, I'll link to it, but given the search engine here, it's not likely.

                              Well, I'll be D'ed! Here's our dust collection system: It's now been running for a couple of years, and has passed several inspections, OSHA, FDA, Fire Marshal, and health dept.
                              Last edited by TGTimm; 02-10-2017, 03:18 PM.
                              Timm Turrentine

                              Terminal Gravity Brewing,
                              Enterprise. Oregon.