Guidelines for Combustible Dust Hazard Analysis

Combustible dust can lead to catastrophic fires and explosions if not managed appropriately. The following conditions are required to initiate a dust explosion: fuel, oxygen, dust disbursement, dust confined in a specific space, and an ignition source. If all five are present, you are in serious danger of a dust fire or explosion.

Here’s how it works. The pressure wave from an explosion may dislodge accumulated dusts in the area, including “fugitive” dusts that have concentrated on equipment, overhead beams, drop ceilings, floors, etc. In some cases, a second explosion happens soon after, igniting the fugitive dust now dispersed in the air. The damages can range from minimal to catastrophic.

Getting these risks under control is critical to your operations. The best way to mitigate risk? Conduct a combustible Dust Hazard Analysis (DHA) which is a systematic evaluation process to identify and mitigate risks associated with combustible dust within a facility. 

Interested in learning the guidelines for combustible dust hazard analysis? Read on.

What is required for a dust hazard analysis?

A DHA analysis involves multiple key steps to ensure that all aspects of combustible dust risk are assessed, addressed, and mitigated. The guidelines for combustible dust hazard analysis are listed below.

1. Identify dust hazard locations. The first step in a DHA is to identify all areas within the facility where combustible dust is generated, processed, or handled. This includes dust-producing operations like cutting, grinding, or pulverizing. Identify places in your facility where dust typically accumulates and determine if they are near heated equipment.
2. Material characterization. Determine what type of material is being used in your facility and its combustibility. This will likely be dependent on moisture, particle size, and other variables.
3. Evaluate your process to control combustible dust risks. Conduct a thorough examination of all equipment and systems that handle combustible dust. Look at dust collection, storage, and conveying systems, and safeguards such as venting, suppression systems, and spark detection.
4. Analyze housekeeping practices. The DHA must assess the effectiveness of current housekeeping practices in controlling dust accumulation. It’s critical that this step identify any housekeeping practices that actually disperse dust into the air. Is a well-meaning staff member sweeping up dust? They may be unknowingly dispersing dust into the air, leading to a fire hazard.
5. Find ignition sources. All potential ignition sources must be identified and evaluated. This includes electrical equipment, hot work operations, static discharge, frictional heating, and more.
6. Make recommendations to mitigate risk. The DHA should provide a risk assessment that prioritizes identified hazards based on their potential impact and likelihood – and recommendations to make your facility better protected. Following this assessment, a risk management plan should be developed to address these hazards, which may include engineering controls, administrative changes, and training.
7. Follow through and measurement. Track the effectiveness of corrective actions and periodically check on your progress. Ensure that ignition sources are safeguarded, airborne dust levels have reduced, and less dust is accumulating on surfaces all around your facility.

Does OSHA require a dust hazard analysis?

OSHA has a series of mandatory requirements regarding combustible dust including provisions addressing specific aspects of combustible dust hazards. General industry 29 CFR 1910 has subparts explaining general working requirements, emergency action plans, ventilation, and more. 1910 subpart R offers specifics on various industries such as paper mills, bakeries, electric power generation, and grain handling facilities. OSHA also has many voluntary guidelines for employers and employees.

OHSA can site companies for inadequate protection of combustible dust risks. The citations typically come from violations of OSHA’s general duty clause or NFPA 652: Standard on the Fundamentals of Combustible Dust. NFPA 652 provides the general requirements for management of combustible dust fire and explosion hazards. In a September 2020 update, the standard requires a combustible Dust Hazard Analysis (DHA) to identify and evaluate risks such as fires, flashfires, and explosions.

How often is dust hazard analysis required?

NFPA 652 requires a dust hazard analysis every five years, even if no changes have been made to your facility or processes. A DHA is also required if you have made new installations or expanded or upgraded existing installations. OSHA generally expects facilities to implement the recommendations from a combustible dust hazard analysis within two years.

What are the OSHA guidelines for combustible materials?

OSHA has many guidelines for combustible dust hazard analysis, including robust guidelines on identification and abatement of dust hazards. Many are in its Fire Protection and Prevention 1926 Subpart F requiring that storage sites be kept free of the accumulation of combustible materials, no combustible materials be stored outdoors within 10 feet of a building, clearance be maintained around lights and heating units to prevent ignition, and more. OSHA also has plenty of rules identifying combustible and flammable liquids.

What NFPA standards regulate combustible dust?

NFPA 652 offers dust hazard analysis requirements and requires that a DHA be completed every five years. It offers high-level standards on the management of combustible dust fire and explosion hazards.

NFPA 654 presents safety measures to prevent and mitigate fires and dust explosions in facilities that handle combustible particulate solids, which include combustible dusts, fibers, flocks, flakes, chips, and chunks. Recommendations include minimizing dust escape from equipment and ventilation systems, using dust collection systems, dust residue inspections, and cleaning methods that don’t generate dust clouds.

NFPA 61 lays out protections for handling grains that have not undergone processing or size reduction. It also outlines the engineering of dry material handling systems such as batching systems, bulk bag unloading, and bulk bag filling systems.

NFPA 484 applies to metal dusts and alloys capable of producing combustible powder or dust and potentially leading to fire or explosions. It covers the production, processing, finishing, handling, recycling, storage, and use of those materials and operations using those materials. It also discusses additive manufacturing and has provisions for safe system shutdown, usage of conductive powder, and shipping and handling.

Want to learn more about dust hazard analysis? Download our whitepaper Protect Against Combustible Dust Fires and Explosions today.