Dust Hazard Analysis (DHA) Consultants

The buyer problem

Any facility that manufactures, processes, conveys, or collects combustible dust (metal powders, wood fines, grain and food dust, plastics, pharmaceutical powders, coal, and more) carries a fire and explosion risk. NFPA has required a written Dust Hazard Analysis (DHA) for existing facilities since September 2020, and the standard governing that requirement was itself rewritten in the 2025 edition of NFPA 660, which folded several older dust standards into one document. OSHA has no dedicated combustible dust regulation, but it already cites facilities under general housekeeping and electrical rules, and under the General Duty Clause when nothing more specific applies. Property insurers are increasingly layering their own dust hazard review requirements on top of that. Most buyers come to this purchase under pressure: a past-due DHA, a new process line, an insurance audit finding, an OSHA letter, or a near-miss. The complication is that, unlike many EHS purchases, there is no single license or certificate that automatically qualifies a person to lead a DHA. Vetting who actually did the work, and how, falls on the buyer.

What a dust hazard analysis (dha) consultants vendor does

A DHA consultant walks a facility process step by process step (receiving, size reduction, conveying, dust collection, blending, packaging) to identify where combustible dust is generated, where it can accumulate, and where an ignition source could reach it. That normally includes arranging lab testing of actual dust samples pulled from the site, rather than relying only on published data for a similar generic material, reviewing existing engineering controls (dust collectors, explosion venting, isolation devices, housekeeping practices), and comparing findings against the applicable NFPA requirements for that occupancy type. The deliverable is a written report: material hazard data, a hazard finding by process area, and specific, numbered recommendations the facility can act on, along with a gap list against current code. Some firms also help coordinate implementation of protection systems (venting, suppression, isolation) with a separate engineering or equipment vendor, though DHA work and protection-system design are commonly scoped and billed separately.

Methods and techniques

• ASTM E1226 (explosibility of dust clouds, Kst and Pmax measured in a 20-liter sphere)
• ASTM E1515 (minimum explosible concentration, MEC)
• ASTM E2019 (minimum ignition energy, MIE, of a dispersed dust cloud)
• ASTM E1491 (minimum ignition temperature of a dust cloud)
• ASTM E2021 (minimum ignition temperature of a dust layer)
• Process-hazard-style walkthrough adapted for combustible dust, following the CCPS (Center for Chemical Process Safety) Guidelines for Combustible Dust Hazard Analysis methodology
• Tiered screening approach: an initial screening DHA to flag processes needing detailed analysis, followed by a detailed DHA where the screening result is unclear or the risk is significant
• Hazardous (electrical) area classification review against NEC Class II Division 1/2 (Article 502) or the Zone 20/21/22 system (Article 506, harmonized with IEC practice)

What to verify before you retain

• Who the 'qualified person' actually is. NFPA's DHA standard requires a 'qualified person' but sets no fixed license, degree, or certificate requirement, and NFPA guidance is explicit that credentials like PE, CIH, CSP, or CFPS alone do not automatically qualify someone to lead a DHA. Ask for the named lead's specific combustible-dust project history. General safety credentials on their own are not a substitute for that history.
• Real lab testing versus literature values. Confirm whether Kst, Pmax, MEC, and MIE figures will come from actual ASTM-method testing of samples pulled from your process, at an accredited lab, or from generic literature values for a similar material. Particle size, moisture content, and process conditions change explosibility significantly, so a 'typical value' from a different plant is not a substitute for testing your material.
• Which edition of the standard governs the work. NFPA 660 (2025 edition), effective December 6, 2024, consolidated NFPA 61, 484, 652, 654, 655, and 664 into a single standard. Ask directly whether your DHA will be performed to NFPA 660 or to the legacy standalone standards, and how the vendor handles any gap if your occupancy classification changes under the new structure.
• Report depth and traceability. Ask to see a redacted sample report so you can confirm it documents findings by individual process step, cites the specific code sections it is evaluating against, and issues numbered, trackable recommendations rather than generic boilerplate language reused across clients.
• Insurer requirements versus the DHA scope. If your property insurer requires its own review, for example against FM Global's Property Loss Prevention Data Sheet 7-76 on combustible dusts, confirm whether the DHA scope covers that separately or only the NFPA-driven analysis. These are not automatically the same deliverable.
• Review cadence commitment. Confirm whether the proposal includes the recurring review cycle NFPA requires (at minimum every five years) or is scoped as a one-time engagement, and what would trigger an earlier re-analysis, such as a process change, new equipment, or an incident.

Questions to put in your RFP

1. Who is the named qualified person who will lead our DHA, and what is their specific project history with combustible dust (facility types, process types, number of years)?
2. Will dust samples from our actual process streams be sent to an accredited lab for ASTM E1226, E1515, E2019, E1491, and/or E2021 testing, or will findings rely on published literature values for similar materials?
3. Will this DHA be performed against NFPA 660 (2025) or the legacy NFPA 61/652/654 framework, and how will you handle it if our occupancy classification changes under NFPA 660?
4. Can you provide a redacted sample DHA report showing the level of process-step detail and the recommendation format we should expect?
5. What is included in the base scope versus billed as a change order: initial screening, detailed DHA, hazardous area electrical classification review, and follow-up verification after we implement recommendations?
6. Do you carry professional liability (errors and omissions) insurance specific to safety consulting work, and what are the coverage limits?
7. What is the proposed timeline from site visit to final signed report, and does that timeline include turnaround for material testing at an outside lab?
8. How will you document the required review cycle, and what specific conditions would you flag as triggers for an earlier re-analysis?

Red flags

• Vendor quotes a fixed price and turnaround before seeing the facility, process list, or material types involved.
• Vendor cannot name the individual who will actually lead the analysis or describe that person's relevant combustible-dust project history.
• Vendor proposes to skip material testing entirely and use generic 'typical' literature values for a material with no test data on file matching your specific particle size and process conditions.
• Vendor presents a generic checklist-only walkthrough with no facility-specific, process-step-level analysis or numbered, written recommendations.
• Vendor implies or states the report will guarantee a pass on an OSHA inspection or insurance audit. A DHA is a hazard analysis, not a compliance certification, and no credible provider guarantees a regulatory outcome.
• Vendor or its proposal shows no awareness that NFPA 652, 654, 61, 484, 655, and 664 were consolidated into NFPA 660 (2025 edition, effective December 6, 2024).
• Proposal makes no mention of the recurring review requirement and treats the DHA as a one-time deliverable with no update path.

Standards and governing bodies

Bodies referenced in this category. Listed for context; they do not endorse this index or any provider. Verify any credential directly with the issuing body.

NFPA

National Fire Protection Association. NFPA 660 (2025 edition), effective December 6, 2024, consolidated NFPA 61, 484, 652, 654, 655, and 664 into a single standard for combustible dusts and particulate solids. NFPA also separately publishes NFPA 68 (deflagration venting) and NFPA 69 (explosion prevention systems), which DHA recommendations commonly reference for protection-system design.

OSHA

Occupational Safety and Health Administration. No dedicated OSHA standard covers combustible dust specifically. OSHA cites dust hazards under 29 CFR 1910.22 and 1910.176(c) (housekeeping), 29 CFR 1910.307 (hazardous electrical locations), and the General Duty Clause (OSH Act Section 5(a)(1)) when no specific standard applies. OSHA's Combustible Dust National Emphasis Program (CPL 03-00-008) was last revised in January 2023.

ASTM

ASTM International. Publishes the test methods behind DHA material characterization data, including E1226 (Kst and Pmax explosibility in a 20-liter sphere), E1515 (minimum explosible concentration), E2019 (minimum ignition energy), E1491 (cloud minimum ignition temperature), and E2021 (layer minimum ignition temperature).

NEC / NFPA 70

National Electrical Code. Article 502 classifies hazardous dust locations as Class II, Division 1 or 2, and Article 506 provides the equivalent Zone 20/21/22 classification system; both draw on the general hazardous-locations framework set out in Article 500. Together they govern what electrical equipment is permitted where combustible dust is present.

IEC

International Electrotechnical Commission. IEC 60079-10-2 is the international standard for classifying combustible dust atmospheres into hazardous zones, relevant when a facility or equipment sourcing needs to align with the Zone system used outside the traditional US Class/Division approach.

FM Global

FM Global. A private commercial property insurer, not a regulatory body. Its Property Loss Prevention Data Sheet 7-76 (Combustible Dusts) sets its own hazard mitigation expectations that some insurers require separately from, and in addition to, a code-driven DHA.