From: Curtis, MarthaTo: Jason Reason (jreason@dol.in.gov)Cc: Goyette, Joanne; Mucci, PattiSubject: FW: FW: NFPA 484 Wet Dust Collector QuestionDate: Friday, March 19, 2010 11:19:43 AMAttachments: CCF01282010_00000.jpg

CCF01282010_00000.jpgImportance: High

Jason, Thank you for your patience while I circulated your inquiry to the NFPA 484 TC for their assistance.The following information has been provided in response to your question. In regard to the question on venting, the intent of the 6.3.4.1.2 was to allow for those raresituations in which operations required air temperature and humidity which need to be closelymaintained for the product quality, and that exhausting to the exterior of the building made it difficult tomaintain temperature and humidity control; or those situations such as at Boeing where portable unitsare required that cannot be adequately vented to the exterior.

Appropriate venting or monitoring of the sump area and exhaust to ensure hydrogen build-up doesnot occur must be accomplished. If this is a fixed installation, venting to the exterior of the buildingshould occur.

It is important to note again that the intent of 6.3.4.1.2 was to allow an exception to those rarecases mentioned above. With that in mind with regard to clean air being returned to the work area, theconcern was that combustible fugitive dusts would not be released into the structure that couldaccumulate over time and present fugitive dust fire and/or explosion hazards.

With regard to who the testing agency should be, it must be one which is acceptable to theauthority having jurisdiction, in this case OSHA, to certify that if the air off the filter is to be recycledwithin the structure, that the filter is efficient enough to prevent combustible metal fugitive dustaccumulations. Whether it is the employer or manufacturer who is responsible for the testing, I do notbelieve matters. The bottom line is a testing agency must certify that the exhausting of the air streaminto the structure will not present a hazard to the personnel and structure from fugitive dustaccumulations that may occur over time. I would imagine the test would require actual operationsutilizing the machinery and product that will be collected when the equipment is operating, and that inchanges in equipment and/or process would require additional testing to ensure appropriatecapture/cleaning of the recycled air.

I believe it was the Committee's intent for wet filters to be exhausted to the exterior, but in order toallow for those unique circumstances where venting was not possible, to allow an exception for recyclingthe air. In most cases, it will involve the utilization of secondary filtration that will need to bemaintained and monitored.

I hope this information is useful for your purposes. Thank you for using NFPA codes and standards. Regards, Martha Curtis

Martha H. CurtisSenior Chemical Specialist/Staff Liaison to NFPA 484NFPA1 Batterymarch ParkQuincy, MA 02169-7471Phone: 617-984-7496Fax: 617-984-7110Email: mcurtis@nfpa.org

********************************************IMPORTANT NOTICE: This correspondence is not a Formal Interpretation issued pursuant to NFPA

mailto:/O=NFPA/OU=NORTH AMERICA/CN=RECIPIENTS/CN=MCURTISmailto:jreason@dol.in.govmailto:jgoyette@NFPA.orgmailto:pmucci@NFPA.org

regulations. Any opinion expressed is the personal opinion of the author, and does not necessarilyrepresent the official position of the NFPA or its Technical Committees. In addition, this correspondenceis neither intended, nor should be relied upon, to provide professional consultation or services.*******************************************NFPA Membership keeps you Up-To-Date! Visit www.nfpa.org/join for more information or call 1-800-344-3555

> Martha H. Curtis> Senior Chemical Specialist/Staff Liaison to NFPA 484 NFPA> 1 Batterymarch Park> Quincy, MA 02169-7471> Phone: 617-984-7496> Fax: 617-984-7110> Email: mcurtis@nfpa.org >> >> NFPA Membership keeps you Up-To-Date! Visit www.nfpa.org/join> for more information or call> 1-800-344-3555>> >> From: Reason, Jason [mailto:jreason@dol.IN.gov]> Sent: Tuesday, February 02, 2010 7:52 AM> To: Curtis, Martha> Cc: Kidwell, Mick; Cook, Suellen> Subject: NFPA 484 Wet Dust Collector Question> Importance: High>> >> Martha,>> >> I have a question about wet dust collectors used to collect aluminum> dust and/or powder (Chapter 6 of NFPA 484-2009). I am researching a> wet dust collector that an employer wants to install to abate (fix) a> General Duty Clause citation we issued for not conveying aluminum dust> to a dust collector. Information about the wet dust collector is> attached to this email for your reference, and it essentially consists> of two downdraft tables with a dust collector in the middle. I am> pretty sure they can place this dust collector inside of the facility> without explosion protection, but I have questions about how the> exhaust from the dust collector needs to be handled. My questions are> about Section 6.3.4.1 of NFPA 484, which states that "the exhaust vent> shall terminate outside of the building and shall be securely> fastened." I believe this is required to get rid of any hydrogen> generated during the wet removal process. After I explained this> requirement to the wet dust collector manufacturer, they stated that> the employer did not have to exhaust the dust collector to the outside due to 6.3.4.1.2.>> >> My questions are what does NFPA 484 mean by "clean air" in Section> 6.3.4.1.2? Does this mean that the air must be filtered prior to> being returned to the work area? If it does need to be filtered, what> type of filter should be used? 6.3.4.1.2 also mentions that "tests> conducted by an approved testing organization" are required to "prove

mailto:mcurtis@nfpa.orghttp://www.nfpa.org/joinmailto:jreason@dol.IN.gov

> that the collector's efficiency is great enough to provide safety to> both personnel and property." What specifically is required to be> proven in these tests and who is required to perform them (the> manufacturer or the employer)? Also, what tests need to be done and> do they have to follow recognized testing methods (OSHA, NIOSH, ACGIH,> ASTM, etc.)? Are they required to test the hydrogen or aluminum> levels in the immediate area in and around the dust collector?>> >> If you are the person this needs to go to, could you please forward> this to the correct person and have them email or call me> (317-372-2042) with answers to the above questions when they get a> chance. The employer is waiting to install this until we (or in this> case I) ok the unit, so I need to get answers to these questions and> then discuss things with the dust collector manufacturer.>> >> Thanks for all of your help and I look forward to finally meeting you> in a few weeks.>> >> Jason Reason>