Chemical Safety Evaluation & Testing

Calorimetry & Dust Explosibility Testing

Reaction calorimetry (RC1 / ARC) + 20-L sphere / MIKE / Hartmann tube — generating ATEX / NFPA 660 design data

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What this study delivers

Calorimetry & Dust
Explosibility Testing

Specialised laboratory testing for reactive chemistry and combustible dust generates the engineering data that underpins vent sizing per DIERS / NFPA 68, suppression design per NFPA 69, ignition-source control per IEC 80079-36 / EN 1127-1, and ATEX Zone classification per IEC 60079-10-2. The reaction-calorimetry stack — DSC (mg-scale screening), RC1 (mL isothermal kinetic), ARC (mL-scale adiabatic worst-case), VSP2 / Phi-Tec (10 mL adiabatic two-phase), Mettler Toledo HEL — produces complementary datasets feeding Stoessel criticality and DIERS vent-sizing methodology. The dust-testing stack — Hartmann tube (legacy MIE screening), MIKE 3 (modern MIE per EN 13821), Godbert-Greenwald or BAM oven (MIT per EN 50281-2-1), 20-L sphere (Kst / Pmax per EN 14034 / ASTM E1226), MEC apparatus (EN 14034-3) — generates the parameters required for Zone 20/21/22 classification, vent area calculation, suppression bottle sizing, and inerting LOC determination. Most industrial powder facilities operate without site-specific dust data — relying on generic K-values that under-protect their actual material; OSHA NEP and FM Global increasingly demand site-specific testing.

Calorimetry & Dust Explosibility Testing — Overview
Study execution

How the study is executed

A structured, facilitated process — from scope definition through close-out — producing defensible, actionable outputs.

Dust Sample Preparation & Characterisation

Prepare dust sample per ASTM E1226 / ISO 6184 — sieve to typical -200 mesh (<75 μm), measure particle size distribution (laser diffraction), moisture content, and bulk density; align with NFPA 660 sample protocol.

Explosibility Screen (Yes / No)

Conduct explosibility screen per ASTM E1226 modified Hartmann tube or 20-L sphere; classify as explosible (yes / no) per NFPA 660 / IEC 80079-20-2; if yes, proceed to quantitative testing.

Kst / Pmax Testing (20-L Sphere)

Conduct Kst and Pmax testing in 20-L Siwek sphere per ASTM E1226; calculate Kst (bar·m/s) and Pmax (bar); classify per ATEX Dust Class — St 0 (Kst=0), St 1 (0-200), St 2 (200-300), St 3 (>300).

MIE / MIT / LOC Testing

Conduct MIE (Minimum Ignition Energy) per ASTM E2019, MIT (Minimum Ignition Temperature) per ASTM E1491 (layer) / E2154 (cloud), and LOC (Limiting Oxygen Concentration) per ASTM E2079; align with NFPA 660 / IEC 80079.

Hybrid Mixture & Conductivity Testing

For hybrid dust-gas atmospheres, characterise interaction effects — MIE depression, MEC reduction, Kst modification; conduct conductivity testing (volume resistivity per ASTM D257) for static-ignition risk assessment.

DHA Input & Vent Sizing Data

Compile testing report with full Kst / Pmax / MIE / MIT / LOC / MEC results; align with NFPA 660 DHA (Dust Hazard Analysis) input requirements; specify vent sizing per NFPA 68 with Kst input; align with NFPA 69 suppression design.

Calorimetry & Dust Explosibility Testing — Scope
Study scope

What the study covers in full

DSC screening for mg-scale thermal events — onset temperature, ΔH, decomposition energy
RC1 isothermal calorimetry — kinetic resolution, dose-control feedback, heat-flux profile
ARC adiabatic worst-case with Phi correction for runaway TMR / SADT determination
VSP2 / Phi-Tec two-phase calorimetry for DIERS vent-sizing — vapour / gassy / hybrid system
20-L sphere Kst / Pmax testing per EN 14034-1/-2 with St 1 / 2 / 3 classification
MEC (Minimum Explosible Concentration) testing per EN 14034-3 / ASTM E1515
MIE testing per EN 13821 — MIKE 3 with capacitor discharge (1 mJ to 1000 mJ range)
MIT (Minimum Ignition Temperature) per EN 50281-2-1 — Godbert-Greenwald cloud / BAM oven layer
LOC (Limiting Oxygen Concentration) determination for inerting strategy
Volume resistivity and chargeability per EN 13335 for electrostatic hazard assessment
Why it matters

Outcomes of Calorimetry & Dust Explosibility Testing

Dust / Energetic Material Hazard Quantification
  • Generates site-specific data replacing generic K-values that under-protect actual dust
  • Identifies MIE <10 mJ dusts requiring electrostatic-bonding control
  • Defines defensible vent area, suppression mass, and isolation design
  • Anchors inerting LOC for nitrogen blanketing strategy
NFPA 660 / UN TDG Testing Defence
  • NFPA 660 (2024 unified) DHA data requirement
  • DIERS-compliant calorimetric data for two-phase vent sizing
  • ATEX Zone classification per IEC 60079-10-2 with EN 14034 evidence
  • FM Global / OSHA Combustible Dust NEP audit-defensible data
Process & Storage Design Improvement
  • Targets dust-collection ventilation design to actual MEC / Kst
  • Drives grounding / bonding programmes against measured volume resistivity
  • Informs inerting nitrogen flow vs measured LOC
  • Supports realistic vent-panel and isolation-valve specification
Testing-Led vs Incident-Led Cost
  • Avoids the 30–50% vent / suppression over-specification of conservative generic values
  • Reduces inerting nitrogen consumption through measured-LOC operation
  • Targets electrostatic-control investment to genuine MIE risks
  • Supports FM Global premium-tier dialogue with measured data
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