November, 2020

202001NovAll DayUnloading PowdersEPSC Learning Sheet | Avoid sparks when unloading powders Origin: EPSC Lessons:Operational Integrity,Process KnowledgeLanguage:EN TagsElectrostatic

Summary

What Happened:
While unloading combustible powder from a FIBC type C Big Bag, a dust explosion occurred.

Aspects:
• If a type-C FIBC is not properly grounded it turns into a potential electrostatic ignition source (isolated conductor)
• Flowing of non-conductive powders will generate static charges that can accumulate and result in spark discharges
• Flammable volatiles (>0.5 w%) do increase ignition risk
• Validate that the grounding & bonding work well. The drawing shows how instruments can be used to assure this.
• Assure that bags including the inner-liner dissipate electricity well: the specs are defined in IEC 61340-4-4
• Avoid that operators get charged (shoes, clothing, earthing)
• Keep the unloading area dust free

Origin

EPSCEuropean Process Safety Centre

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