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30 / July 2020 powderbulk.com which can range from interviews and documents to references. Some customers duped by "experts" have spent thousands of dollars on atrocious DHA results that weren't suitable for the bottom of a birdcage. Planning your DHA timetable One of the most frequently asked questions regard- ing DHAs is how much time the analysis will require. The time it takes to complete a DHA depends upon multiple factors such as your facility's complexity, the processes and bulk handling systems involved, and the number and type of combustible dusts involved. Some DHAs can be completed in a single day, while others have taken a week or more to finish. What's cer- tain is that a DHA needs to be done only once every 5 years, barring any changes that affect the initial DHA results. Often, a completed management-of-change document can suffice for changes that affect the initial DHA results, but this advice doesn't apply to all pro- cess changes; some may require an all-new DHA to be completed. And again, a DHA does require updating every 5 years. Preparing for your DHA Before beginning your DHA, certain tasks should be completed to provide adequate information to prop- erly execute the DHA. Some of these tasks are optional, depending upon multiple factors and preferences, and some are compulsory. Material testing, or obtaining the data from previous test results, of the involved com- bustible dusts is a highly important task that must be completed before the DHA begins. This task is referred to as "hazard identification" and is covered in Chapter 5 in all standards that are 2019 editions and later. The following is a compressed version of the manda- tory material testing requirements. • Test your materials for K St , P max , minimum ignition energy (MIE), minimum explosion con- centration (MEC), and any other explosivity characteristic — such as volumetric resistivity, ignition temperature, and others — that would influence the DHA. Having historical data avail- able for your materials in lieu of testing is suitable in some cases. • If many materials are involved, testing them all may not be necessary. If the materials are handled similarly, testing those that cause the most dam- age in an explosion is acceptable. • Make sure the material sample used is truly rep- resentational of the material. • The sample must also represent the actual haz- ards and risks. Therefore, it's recommended that the sample be a dust as opposed to larger parti- or mitigate the hazards, and ensure the safety of per- sonnel and property. Because of the DHA's purpose, completing a DHA before a system is fully designed is most logical and best practice. This allows for any adjustments to be made to the system or process. Then, once the system has been put in place and used, the DHA can be revised and confirmed as appropriate. Personnel involved in your DHA A critical question to ask yourself is who should be involved in the DHA. Ultimately, a facility's owner or operator is responsible for the completion and content of the DHA and the subsequent implementation of any necessary DHA action plan based on the results. Other experts or people who assist in the DHA won't be held responsible. Normally, conducting and com- pleting a DHA isn't feasible for just one person — even a knowledgeable one. An experienced facilitator is recommended to help perform the DHA. This facili- tator can be someone familiar with process hazards analyses (PHAs) or the NFPA combustible dust stan- dard requirements. Having one or more individuals who are fully experienced in the DHA process and bulk handling requirements of the processes involved is also critical. This could include processes such as dust collection, conveying, drying, and milling, among others. These individuals must also be fully up to date on the NFPA combustible dust standards and related regulatory requirements, for example IFC and IBC. Additionally, the plant manager; plant engineer; environmental, health, and safety (EHS) manager; maintenance manager; and other managerial personnel are typically involved in a DHA. Additional part-time participants would include operators, supervisors, and other personnel directly involved in various plant operations where combusti- ble dusts are present. Perhaps the most critical person involved would be the secretary or recorder, who doc- uments the discussion and results using an electronic display device. Proper documentation of the process and results is critical, and these records must be maintained for the life of the process, facility, or both where applicable. There's no need to involve regulatory agencies in your DHA as this analysis is strictly for the facility. And while the completed DHA isn't made public, the documentation must be kept for plant refer- ence and planning and must be available for regulatory personnel if requested. A word of caution: Ever since NFPA 652 initiated the need for the DHA, so-called "experts" have been coming out of the proverbial woodwork. If experts are employed to assist in a DHA, verify that they're truly experts in the selected field. Ask them for proof of this,