Issue link: https://www.e-digitaleditions.com/i/1263839
July 2020 / 33 What is the purpose of zone 3? Zone 3 provides for the collection, control, and disposal of the ne dust parti- cles carried by the process air ow stream to prevent additional dust emissions within the process area. What is the purpose of node P (dust collector)? Node P (dust collector) separates the incoming air-dust mix- ture. The clean air goes through the lters, and the dust goes to the bottom where the particulates will be discharged through node Q (rotary valve) into the pneumatic transfer system. The lters are continuously cleaned using an automatic pulse-jet-type system. Can combustible dust be suspended in air? Yes, combus- tible dust can be suspended in air. Fine dust constantly exists suspended inside node P (dust collector) and especially when the lters are pulse-cleaned with compressed air (continuous and automatic). Dust levels above the MEC are nearly constantly present. If a de agration event was to occur inside node P (dust collector), can the heat propagate? Yes, since there's no explosion protection or mitigation and no isolation provided, any de agration in the collector would prop- agate throughout the entire ducting system and to the multiple hood and venting connections that are dust sources. The result would be catastrophic. Are there credible ignition sources? Yes, credible igni- tion sources include embers from any of the devices directly or indirectly connected to the system, such as the mill, for example. Since the dust is pyrophoric, there's the possibility that the dust could sponta- neously heat as there are multiple ledges and other spaces in the unit where material accumulates and stays for long periods of time. This scenario is a de - nite and credible hazard with viable ignition sources that could have catastrophic results. Are there plant personnel present or involved? The dust collector is elevated, and normally, only maintenance personnel are around the equipment. Operators aren't normally around the unit. What methods of explosion management and mitigation exist? None, except for irregular inspections and pres- sure differential measurements across the lters. No de agration protection or other mitigating equipment or methods are provided. Is special PPE required for personnel around node P (dust collector)? No special PPE is required except for needing a con ned space permit when entering the unit. Are there other factors to consider? A multitude of factors in the proper unit and system design should be taken into consideration, but these factors can't all be covered here. There are many checklist and what-if items that would be involved in a DHA. The previous text was only an example and only included partial checklist Process While Conveying. Move and process your bulk materials at the speed you want in the volume you need with a Carman Vibrating Conveyor. Carman's solutions are custom designed for your application. Call us today at 800-456-7560 or email for a FREE brochure. info@carmanindustries.com • 800-456-7560 www.carmanindustries.com Versatile Conveying! Designed, Built and Tested in the USA.