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1 Appendix D 1. REPORT OF THE SUBPANEL ON RECOMMENDED STANDARDS AND REGULATIONS A subpanel of the Panel on Causes and Prevention of Grain Elevator Explosions was formed to review existing regulations and standards and to make recommendations that will reduce losses. The work was limited to grain elevators and did not include feed mills and processing plants although much of the information is transferable. The recommendations are not of grain elevator design nature, though it was recognized that a need exists, but rather are directed at existing operating grain elevators. 1 The subpanel a cco~npl ished the following: 1. Peviewed existing regulations and standards Established facts about explosions that would be a basis for credi table regulations Made regulation recommendations REVIEW OF EX ISTING REGULATIONS There doers not exist a regulation specifically for grain elevators, but there are same standards, alerts and instructions which have been reviewed. The following matters were reviewed: l 1. Occupational Safety and Health Administration Grain Elevator Industry Hazard Alert - January 5, 1978 Letter S/19/78 Le tter 7/18/78 2. U.S. Department of Agriculture Federal Grain Inspection Service FGTS Ins truction 370-3 Rev. 1 Alert Gu ideline Procedures and Policies -upon Encountering "Hazardous Conditions. in Grain Elevators. Ma tional Fire Protection Association Grain Elevators Bulk Handling facilities 1973 NE PA 61B 127 1

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128 4. Industry Safety Standards - Continental Grain Company - Bunge Corporation - Cargill, Inc. 5 . State of Mi chigan De pa rtment of Labor Occupational Safety Standards Commission Part 77 Grain Elevators and Mills Occupational Safety and Health Administration Hazardous Materials Fire Protection Occupational Safety and Health Administration Longshoring - Draf t 8 . Ma tional Electrical Code - Article 500 - Hazardous Locations Panel 14 - Peview draft The majority of the regulations reviewed were either interim in concept or are being reviewed at this time. For this reason, the subpanel opted to avoid specific review of individual documents, but make general comments only and move on to the positive work of recommendations for effective regulations. Regulations are too lengthy, containing support data, opinions, statistics and design criteria in addition to the regulations. More than half of all grain elevators have two or less employees who must handle all the management functions including loss control, and they require a simple clear regulation. When part of the regulation is based on controversial opinion, the entire regulation loses credibility and results in a low level of campl lance and court cost, dissipating capital that should be employed in loss control. Efficient regulation focuses on reduction in loss of life, limb and property. BASIC FACTS To draft an efficient regulation it is first required to establish the basic facts to support the regulation. At present, statistics in the industry are poor and sane additional research is needed to eliminate the controversy over such questions as the role of metal sparks in dust cloud ignition. The following are facts on which an efficient, creditable regulation can be written and enforced today. 1. The leg or bucket elevator is the number one location for primary grain dust explosion. 2. Poor housekeeping and inadequate dust control leads to disastrous secondary explosions with high loss of personnel and property. There is little record of primary explosion in working spaces of the elevator and none in large bins, flat warehouses or ship holds. Dust cloud ignition sources may be divided into high and law incidence:

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129 High Hot Bearings Welding and cutting Belt slippage and misalignment Open flames Foreign objects caught in machinery REGULATION ARC - ~NDATION Low - Electrical Static electricity Lightning Metal and stone sparks - Spontaneous combustion 1 A; simple regulation aimed at the bucket elevator and the high incidence ignition sources should eliminate 90 percent of the primary explosions. Regulation of the dust systems and housekeeping will reduce the lass resulting from the few remaining dust cloud ignitions and the secondary explosions. 1. Legs (bucket elevator} within closed elevator spaces a. Should be equipped with motion switches that sound an alarm when belt speed falls 10 percent and shut the leg down i f the condition is not corrected in 30 seconds . b. Bearings should not be mounted inside the leg cas ing . c. A method must be provided to check bearing temperatures each operating day and a record maintained. In small elevators a simple log will suffice . d. The leg discharge should have a plug switch to shut down leg feed or sound an alarm when discharge becomes plugged. e. Receiving leg feeds should be protected by a grate where the greater dimension is less than the cup projection and the lesser dimension is 1/2 the cup projection. f. Leg should have explosion vents to the- outside. The vent should be at least the full size of the head. Vent as near vertical as possible. It is not implied that venting of the head pulley area will be effective for explosions other than those originating in or near the head. g. A written maintenance program including a work log dating belt inspection, cup inspection, pulley lagging inspection, motion and plug switch checks should be undertaken.

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130 2. Electrical a. All closed areas of the grain elevator housing grain-handling equipment should have dust control and housekeeping so as to qualify as Class TI, Division 2 locations. This will include loading and unloading sheds with two or more walls. b. me following will be considered ordinary locations (not as hazardous as Division 2 locations): - Open roof, dock, and yard areas - Buildings containing no grain-handling equipment and separated from those containing grain-handling equipment by fire walls and fire doors - Pressu ri zed rows c. Electrical equipment located within conveyor housing or other containers where dus t concentrations may reach the rawer explosive limit during normal operation shall be suitable for Class II, Division 1. d. All replacement belts and pulley lagging should be conductive having 15 meg ohm or less resistance to ground. All motors should be grounded in accordance with National Electrical Code. 3 . Dus t Control a. Within closed elevator spaces, transfer points and free-fall areas should be dust tight or dust control should be provided. All interior legs should have dart control. b. A maintenance program and work log should be kept on all dus t sys tems wi thin the elevator closed space s . c. Performance of the dust control system should be continuously monitored. 4. Housekeeping in work areas of the building: a . Housekeeping schedules and log" should be kept on al 1 closed areas containing grain-handling equipment. Each gallery, each tunnel, each headhouse shall be deemed an area. b. As a guideline, layered dust in each area should not exceed 1/64" and if made airborne the concentration would not exceed 40 g/m3 (0.04 oz/ft3) for the total volume of the area. Grain spills are not considered here; only that material that will pass through a 200 - Hash screen (7 4 ~ or smal ler in diameter ~ .

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1 5. Procedures 131 Welding and cutting should not be permitted in the elevator when operating and a permit system should be in effect. Electrical and air tools should not be used on grain-handling equipment while running, and a method of control should be in place. An emergency signal system should be in place. 1 d. Emergency procedures should be written and posted. Outs ide contractors working in the elevator should be required to observe the above procedures. 6. The following training will be documented: Emergency procedure drill l b. Explanation of dust explosion pentagon c. Explanation of this regulation d. Annual meeting with local fire department This regulation will be acceptable to responsible grain men, can be enforced, and will eliminate more than 90 percent of the grain elevator dust e "1 as ion problem. 1

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