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36 / May 2020 powderbulk.com EXPLOSION PROTECTION: SAFELY MANAGING PROCESS CHANGES When making changes to powder and bulk solids manufacturing processes, there are many factors to consider, aside from the actual change itself. The effects of any change can go beyond the process and impact a facility's existing explosion prevention and protection systems. This article explains the importance of complete process-change reviews, explains factors to consider, and provides some real-world examples of the potential consequences of incomplete reviews. David Grandaw, IEP Technologies cess and render the current EPP system incapable of responding and protecting as intended. The following examples highlight some real-world consequences of not considering the entire process when making these types of changes. • A bulk solids manufacturer handling a vitamin additive switched from conductive to nonconduc- tive filter bags inside the dust collector, which led to electrostatic charge accumulation on the filters. These charges caused deflagrations in the dust collector over three consecutive days. • A chemical company changed the material being processed, switching to a material with more than triple the explosivity (K St index) of the original material. This increased K St meant that the facil- ity's original EPP system was now undersized for the explosion threat. Since the system was no longer suitable to mitigate a deflagration of this magnitude, structural damage to multiple vessels occurred during an explosion event. • A wood processing facility added an opening in the process line to create additional airflow. The opening adversely affected the explosion pressure detection function of the EPP system, enabling the explosion that did occur to propagate without the system initiating the explosion isolation system. Process changes and explosion risk These are just a few examples of the potential explo- sion-related consequences faced when implementing process changes. The following section discusses how changes in processed material, operating conditions, protected equipment, and interconnections can affect an existing explosion protection strategy within a process. This isn't an exhaustive list, of course. Pro- cess-specific conditions and many other factors also could impact the effectiveness of an EPP system at a facility. Adequately evaluating these factors may require specialized knowledge and involve close dia- I n today's fast-paced, global business environment, the need for manufacturers to adapt and change to take advantage of new market opportunities and technology innovations is ever-present. For chemical, pharmaceutical, food, and other bulk solids proces- sors, introducing new products, altering formulas, and modifying or upgrading a plant for increased produc- tion are all typical factors that might require changes to existing processes. Before implementing any of these types of changes, however, a multidisciplinary, complete, start-to-finish review into all aspects of the change and the expected or potential consequences should occur. A critical focus in this type of review should always be a detailed look at any safety-related change implications. Often termed a hazard and operability study (HAZOP), these types of analyses take into account any impacts the proposed changes would have on the plant, the process, and the people working in the environment. The review must examine the likelihood of an explosion and how any unintended consequences might intensify and com- promise the facility's existing explosion prevention and protection (EPP) systems and their ability to safeguard the plant's integrity. The process review in facilities that handle combustible materials such as loose solids, powder (dust), gases, and vapors is especially vital. In facilities that deal with materials that generate combus- tible dusts, a more specific review called a dust hazards analysis (DHA) is required by NFPA standards and other agencies. DHAs will be discussed later in this article. When processing changes occur Put simply, if correctly specified, a plant's existing EPP system will have been designed to cope with the spe- cific set of materials being processed, the operating conditions, and the plant's equipment design, geome- try, and layout. Alterations to any of these factors can greatly change the explosive characteristics of a pro-