Sep 30, 2021

The Four Ws of Dust Hazard Analysis

The who, what, when and why of DHAs

source: Rembe

Many industrial facilities handle combustible particulate material which pose fire and explosion hazards. Managing combustible dust hazards is critical to ensure the safety of the plant personnel and operations. In order to effectively manage combustible dust hazards they must first be identified and understood.

A dust hazards analysis, or DHA, is a systematic review and assessment of a process and/or facility led by someone with knowledge and experience in understanding and identifying combustible dust hazards. A DHA is a tool to help plant managers and operators address and manage hazards that may not have been otherwise obvious. It is also a documented record of awareness that places a diligence and duty on the plant manager/owner to address the hazards.

NFPA_652_cover_image_(002)

Compliance with the NFPA standards for combustible dust safety, especially NFPA 652 Standard on the Fundamentals of Combustible Dust 2019 requires that a DHA be completed for new and existing processes and facilities where combustible dust is present. The deadline for DHA completion is September 7, 2020, or January 1, 2022 for existing agricultural and food processing facilities not undergoing significant modification. DHA’s must also be reviewed and updated every five years.

An effective DHA includes information to classify and quantify the material(s) as a combustible dust. This is often by reference to material explosibility testing of a representative sample(s) of the dust handled and present in the actual facility and process(es). This may include one or various materials or forms of a single material in a facility. Influential factors can include particle size and moisture content.

The bulk value of a DHA comes from the analysis of each area, process operation and equipment where combustible dust is or may be present. The analysis identifies specific combustible dust fire, flash fire and explosion hazards as well as the potential implications of the hazard event. Combustible dust hazards are assessed on the basis of the dust explosion pentagon components: fuel, oxygen, ignition source, fuel dispersion in air above the minimum explosion concentration and containment. A definitive absence of one component rules out the probability of the dust explosion however; fire and flash fire can be still highly probable. The hazards are identified under the conditions of both normal operation and abnormal or upset conditions. Existing safeguards and hazard reduction or management methods shall be clearly indicated and documented but also assessed for application suitability, reliability and maintenance.

One of the most important aspects of the DHA is specific recommendations to manage the identified hazards and the residual effects or secondary hazards. Recommendations should be as specific as possible and prioritized according to severity and probability of the hazard.

rembe_chart

Additional components of a DHA include assessment, review and recommendations of documentation and procedures with an influence on combustible dust safety. Such procedures include hot work programs, employee and contractor awareness and safety training, safety/protection systems maintenance and documentation, management of change procedures and combustible dust housekeeping.

Following preparation of the DHA document, the job is not finished. In fact, the real work is just beginning. The DHA team must then use the identified recommendations to prepare a prioritized action item list with specific tasks, assigned parties, target timeframes and required resources. This serves as both a guide to hazard reduction and a working document demonstrating reasonable effort towards managing risk.

So, in review:

  • A dust hazards analysis, (DHA) must be completed to be compliant with upcoming NFPA deadlines and is a useful tool for diagnosing and remedying deficiencies in managing combustible dust risks in industrial processes and facilities.
  • NFPA 652 requires that the process be led by someone with knowledge and experience in understanding and identifying combustible dust hazards.
  • Dust testing is a critical step in the process of a DHA so the dust hazards can be appropriately categorized and addressed.
  • Recommendations for addressing deficiencies in managing combustible dust hazards must be documented and addressed in a timely fashion acceptable to the authority having jurisdiction.
  • The DHA must be reviewed every 5 years or updated as processes, equipment or other changes are implemented.

A DHA is a useful tool and resource to manage dust rather than sit on a shelf and collect it.

About Jeramy Slaunwhite
Jeramy Slaunwhite, P.Eng, is a Mechanical Engineering graduate from Dalhousie University in Halifax, Nova Scotia, Canada with over 13 years of applied engineering experience. Slaunwhite has developed expertise in manufacturing, consulting, and governmental environments in fields including material handling, industrial ventilation, mechanical building systems, energy conservation, and project management. Slaunwhite’s career focus on industrial combustible dust assessment and design has developed his exceptional familiarity with the NFPA standards for combustible dust safety.

Recently Added to Buyer's Guide

FSU101 Bag Sealer

  • Seals up to 25 bags/minute depending on size, weight and type of high barrier material
  • Resistance-type heat seal bars with dual temperature controls

I/O Interface

  • Interface forms a smart and universal actuator
  • Offers endless modifications to give full control of exact functionalities

Reconditioned Mixers

  • Comparable to new equipment when properly restored to as-new working condition by ROSS OEM team
  • Comes with the same standard warranty as new ROSS Mixer

Model SBR Conveyor Belt Cleaner

  • Smaller version of its brush-style conveyor belt cleaner
  • Designed to remove fines and carry-back material from conveyor belt

Mid-Roof Walkarounds

  • Permanently installed walkways
  • 360-degree access to grain bin roofs and mounted components

FSU50

  • Seals 2 to 5 bags/minute depending on operator dexterity as well as size, weight and type of high barrier material
  • Foot pedal or proximity switch activation

Magazine

Marketwatch: May, 21

US Corn Price Idx: ZCPAUS.CM

open: 7.6763
high: 7.7267
low: 7.6613
close: 7.6955

US Soybean Price Idx: ZSPAUS.CM

open: 16.601
high: 16.7876
low: 16.596
close: 16.7347

US Hard Red Winter Wheat Price Idx: KEPAUS.CM

open: 12.213
high: 12.3255
low: 11.9455
close: 11.9611

US Soft Red Winter Wheat Price Idx: ZWPAUS.CM

open: 11.2661
high: 11.3836
low: 11.0864
close: 11.0916