What triggers a DHA review before five years?

Changes to materials, particle form, process equipment, throughput, dust collection, building arrangement, operating procedures, or safeguards can invalidate DHA assumptions. Incidents, near misses, test results, or newly identified hazards should also be screened rather than waiting for the periodic revalidation date.

Composition, moisture, particle size, or supplier Equipment, rate, routing, enclosure, or collection Incident, near miss, inspection, or new test result

The source links below support the regulatory, standards-development, investigation, or test-characteristic context stated on this page. DustDHA does not reproduce paywalled standard text and does not turn general source material into a facility-specific engineering conclusion. Where a fact depends on the current NFPA 660 edition, use the official NFPA publication and record the edition reviewed.

Record the material form, process conditions, equipment and enclosure, current safeguards, authority having jurisdiction, and the evidence used. Separate verified facts from assumptions. If a decision affects life safety, explosion protection, code compliance, or a signed engineering deliverable, have a qualified professional evaluate the actual site rather than relying on this summary.