13 pages

Please download to get full document.

View again

of 13
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
  GAPS Guidelines GAP.  A Publication of Global Asset Protection Services LLC DUST COLLECTION SYSTEMS INTRODUCTION  Any facility that handles materials in solid form will generate dust by abrading the solid. The dust generated this way is usually not produced in quantities large enough to be hazardous and can be addressed by regular housekeeping. If the dust in question is combustible, explosive or otherwise reactive, and is generated in large enough quantities to be dangerous, then it must be removed at its source. More recently, similar concerns have risen over dusts which are potentially toxic. Some dusts also contain adhesive materials leading to a residue buildup in, or even clogging of, dust collection systems. Some examples are pressboard, particle board, composites or dust coated with coolant or lubricating residues.  At one time, simply exhausting such dusts to the outside atmosphere was an adequate way to address the problem. Environmental concerns now make it necessary to collect such materials before they pollute the surrounding area. Dust handling systems have therefore grown from simple dust exhaust systems to complex dust collection systems. Because of these constraints, some processes simply cannot operate if the associated dust collection systems are out of service. Although a dust explosion can be large enough to destroy an entire facility, even a relatively small amount of property damage to a collection system can cause a large business interruption loss. Consequently, major loss prevention and control attention to dust collection systems is justified. This section only covers fugitive dust collection systems. It does not address dust collection systems integral to production processes, such as pneumatic conveyors, spray dryers, etc. as these are specific to the individual process. This section does not cover electrostatic precipitators as these are addressed by GAP. POSITION Management Programs Management program administrators should report to top management through the minimum number of steps. They should also institute adequate loss prevention inspection and audit programs to communicate program effectiveness to top management. This management feedback is a key feature of GAP.1.0.1 ( OVERVIEW ), Global Asset Protection Services’ (GAPS) total management program for loss prevention and control. In developing a program, pay particular attention to the following important areas: Material Hazard Evaluation Program Develop a test program to determine the pertinent physical and chemical properties of dusts that are likely to be generated. Choose test conditions that best represent all possible operating conditions. Include in the program the following tests: ã   Minimum explosive concentration of (MEC) dust cloud – ASTM E1515 determines this. 100 Constitution Plaza, Hartford, Connecticut 06103 Copyright   2015, Global Asset Protection Services LLC   Global Asset Protection Services LLC and its affiliated organizations provide loss prevention surveys and other risk management, business continuity and facility asset management services. Unless otherwise stated in writing, our personnel, publications, services, and surveys do not address life safety or third party liability issues. The  provision of any service is not meant to imply that every possible hazard has been identified at a facility or that no other hazards exist. Global Asset Protection Services LLC and its affiliated organizations do not assume, and shall have no liability for the control, correction, continuation or modification of any existing conditions or operations. We specifically disclaim any warranty or representation that compliance with any advice or recommendation in any document or other communication will make a facility or operation safe or healthful, or put it in compliance with any law, rule or regulation. If there are any questions concerning any recommendations, or if you have alternative solutions, please contact us.   GAP. ã   Minimum ignition energy of dust cloud – ASTM E2019 determines this. ã   Sieve analysis – ASTM D1921 determines the particulate size distribution of a product sample. ã   Dielectric data – ASTM D150 determines the various dielectric properties needed to calculate the relaxation time. ã   Maximum rate of pressure rise at optimum concentration - ASTM E-1226 determines this property, also known as Kst. ã   Maximum explosion pressure at optimum concentration – ASTM E-1226 determines this property, also known as Pmax. ã   Resistivity measurements – ASTM D257 determines various electrical properties of the material. ã   Hot surface ignition temperature – ASTM E2021 determines this. ã   Minimum ignition temperature of dust cloud – ASTM E1491 determines this.  As an alternative, obtain data from Material Safety Data Sheets provided by the supplier of the material. Process Hazards Evaluation Program While designing the various facility processes, consider the desirability of reducing the generation of hazardous dusts. Ideally, switch to noncombustible materials, or at least less combustible ones. If that is not practical, improved equipment may produce less dust, and consequently the amount that must be collected and handled will be less. Something as simple as increasing the particle size can markedly reduce the hazard. Determine the safe operating and potential upset conditions of all new or existing dust collection equipment used by the plant. Give special attention to static electricity and to dust buildup on hot surfaces as potential ignition sources. Interlock processes to shut down automatically and safely in the event that associated dust collection systems are inoperative or shutdown, or when their fire protection systems are activated. Operator Training Program Educate all operators in the hazards of the dusts involved and in the functions of the dust control equipment. Authorize operators to stop the process when any of this control equipment is out of order. Train operators in proper start-up procedures as well as manual emergency shut down procedures. Also train operators to respond to upset conditions and to be knowledgeable of required equipment maintenance and available fire and explosion protection systems Promote strict adherence to the written procedures. Housekeeping Design the housekeeping program to keep dust at predetermined safe levels throughout the facility.  Adjust the number of cleaning personnel and equipment and the frequency of cleaning to match the dust accumulation rates under standard operating conditions. Establish an emergency procedure to immediately detect, report and clean up any unexpected dust concentrations. Use fixed vacuum systems rather than portable ones for cleaning. Avoid cleaning methods which tend to raise dust clouds such as vigorous sweeping or blowing down with compressed air or steam. If such methods must be employed, do so only with the following precautions: ã   Vacuum the area thoroughly beforehand. ã   Shut down all electrical systems and any other ignition source. ã   Use only low pressure (15 psi [103 kPa]) compressed air or steam. ã   Ensure that no hot surfaces capable of igniting a dust cloud or layer exist. Duplication of Equipment In cases where a production curtailment would be critical, provide a backup dust collection system.  As an alternative, install several separate smaller dust collection systems instead of one large unit. GAPS Guidelines 2    A Publication of Global Asset Protection Services LLC   GAP. Separate duplicate units by barriers or distance. Keep multiple dust collection systems completely separate by avoiding the use of manifolding. Keep on site a supply of critical spare parts, such as filter bags or bag cages. Location In descending order of desirability, locate dust collectors: ã   Outside. ã   In cutoff attached rooms with three outside walls. ã   In cutoff rooms with one outside wall. ã   In a cutoff interior room. ã   In the same area as other occupancies but with as much distance as possible between the dust collector and any large value item. In accordance with NFPA 654, dust collectors should be located outside unless protected with deflagration vents or an explosion suppression system. Deflagration vents must terminate outside the building or be equipped with a deflagration arrestor. Operations  Avoid the use of dust collection systems to pick up trash or scrap. If such use is unavoidable, arrange the system to separate the scrap and the dusts. For instance, installing coarse screens at the pick up points prevents scrap from entering the system, while coarse filters followed by fine filters separates scrap and dust after they enter the system. Install magnetic separators to remove ferrous materials at or near pickup and dump points.  Avoid the recycling of collector exhaust back into the building. If such an arrangement is unavoidable, install High Efficiency Particulate Air (HEPA) filters so that no dust is carried back into the building. In addition, provide an isolation device to block the propagation of a fire or explosion into the building. Such devices include a local explosion suppression system or a very fast automatic valve. Construction Materials Design and construct dust collection systems in accordance with NFPA 654. Use noncombustible construction in the building. See NFPA 220. Use noncombustible materials to construct dust collection systems. Construct dust collection systems of conductive materials and avoid the use of materials which tend to produce static electric charges such as plastic ducts. If it is not practical to use noncombustible bags in bag type filters, then use materials of the lowest combustibility possible. Use only nonsparking (nonferrous) metals for fan components. Structure Design structures so that they do not collect dust and are easy to clean. Avoid the use of roof supports members with extensive horizontal surfaces or any surface with an angle less than the angle of repose of the dust. Design the internal supports of large ducts so as to not form pockets which would collect dust. Design Design the dust collector fans to maintain negative pressure in the system to avoid dust leaks. Install the fans downstream of the dust collectors so that the dust laden air does not pass through the fans. Design and install electrical systems in accordance with NFPA 70. Protection If a dust collection system is of noncombustible construction and the dust being collected is also noncombustible, no fire or explosion protection is needed. However, if the dust or the collection system construction is combustible, provide the sprinkler and hose station protection listed below. If GAPS Guidelines 3    A Publication of Global Asset Protection Services LLC   GAP. the dust is determined to be explosive, also install explosion protection as needed. See also GAP.2.3.2 for protection of ducts of combustible construction.  Automatic Fire Suppression Install automatic sprinklers inside the dust collection system. Use open head deluge systems activated by fixed temperature detectors for large high value bag houses. Use closed head sprinkler systems for all other dust collection system components. Design the sprinklers in accordance with NFPA 13 and NFPA 15 to provide 0.25 gpm/ft 2  (10.2 L/min/m 2 ) over the entire internal area of bag type dust collectors. Install the heads in the clean air plenum and the fixed temperature detector in the clean air duct. Provide a density of 0.20 gpm/ft 2  (8.15 L/min/m 2 ) over the interior of the ducts, hoppers and cyclones. Design the dust collection system to withstand the weight of the maximum possible water containment. In lieu of that, install automatic drains. Be sure to extend sprinkler coverage beneath dust collection hoods which block ceiling sprinklers.  Although a water based system is preferred, other extinguishing agents, such as CO 2 , dry chemical are acceptable, provided that they are designed and installed in accordance with the applicable NFPA standard. See NFPA 12 and NFPA 17 for details. Courtesy of Fike Figure 1 . Explosion Isolation. Explosion Isolation Install explosion isolation valves in large dust collection systems as needed. Arrange these valves so that a single explosion cannot propagate from unit to unit destroying the entire dust collection system. Figure 1 shows such isolation. Since isolation valves do not protect the individual units where the explosion srcinates, install explosion relief or suppression on the individual units. Figure 2 shows an example of this. Explosion Relief Install adequate explosion relief throughout the dust collection system in accordance with NFPA 68. In descending order of desirability, do the following: ã  For outdoor locations, install the relief panels directly on the dust collectors. GAPS Guidelines 4    A Publication of Global Asset Protection Services LLC
Related Search
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks

We need your sign to support Project to invent "SMART AND CONTROLLABLE REFLECTIVE BALLOONS" to cover the Sun and Save Our Earth.

More details...

Sign Now!

We are very appreciated for your Prompt Action!