Consequence and Dispersion Modelling
We quantify thermal, explosion and toxic consequence zones for risk assessment and emergency planning
Consequence and Dispersion
Modelling
Consequence and dispersion modelling answers the physical question on which siting, emergency planning and quantitative risk all depend, which is simply how far the harm reaches if a containment fails. We trace the chain that a real release follows, from the source term and release rate, through dispersion of the flammable or toxic cloud under the prevailing weather and terrain, to the resulting thermal radiation, overpressure or toxic dose, and we map the credible hazard zones against recognised harm thresholds. Done well the work is neither needlessly conservative nor optimistic, because we choose the right release scenarios, build defensible source terms and use validated models drawn from API 521, the SFPE handbook and the TNO Yellow, Green and Purple Books, executed in tools such as PHAST, so that the numbers withstand scrutiny. The output underpins your facility siting and layout, your emergency and land use planning and the consequence side of QRA, and it turns the question of how bad it could be from an assertion into quantified evidence you can decide on.
How the study is executed
A structured, facilitated process that runs from scope definition through close out and produces defensible, actionable outputs.
Extract loss of containment scenarios from HAZOP / QRA, define representative orifice sizes (small / medium / large), release heights, orientations, fluid phases (vapour, liquid, two phase, cryogenic), and ambient conditions, build scenario register with inventory mass.
Model pool fires (Thomas correlation, SFPE), jet fires (Chamberlain / Cook Cullis), and flash fire LFL envelopes, calculate radiation iso contours at 4 / 12.5 / 37.5 kW/m² thresholds, apply view factor correction for receptor angle.
Apply TNT / Multi Energy / Baker Strehlow Tang for screening scenarios, deploy FLACS or KFX CFD for high consequence VCE cases with congestion parameterisation, produce overpressure and impulse iso contour maps for occupied building and facility siting input.
Model toxic release source terms (flash, two phase, aerosol, evaporating pool) and atmospheric dispersion using PHAST / ALOHA / SAFETI, calculate hazard distances to AEGL 1 / AEGL 2 / ERPG 2 / IDLH / SLOT / SLOD with stability class and wind speed sensitivity.
Model BLEVE fireball (Roberts / Hasegawa correlation) for pressurised liquefied gas scenarios, assess Boilover and tank farm scenarios, combine fire, explosion, and toxic effects for multi effect scenarios including domino escalation thresholds.
Integrate consequence contours into QRA risk aggregation (LSIR / F N), produce GIS compatible hazard distance tables and contour maps, derive Emergency Response Planning Zone (ERPZ), shelter in place criteria, and F&G detector placement inputs per API RP 14C.
What the study covers in full
Outcomes of Consequence and Dispersion Modelling
- We quantify hazard distances so you can design safe layout and escape routes
- We identify the worst case scenarios that define your emergency planning zones
- We support fire and gas detector placement and alarm setpoint determination
- We provide the input to your occupied building risk assessment
- We deliver EPA RMP off site consequence analysis that meets the requirement
- We provide the consequence analysis your COMAH and Seveso safety report needs
- We support the consequence evaluation in your OSHA PSM process hazard analysis
- We satisfy the development control requirements of your planning authority
- We inform safe working distances during hot work and maintenance
- We identify the equipment items that carry the highest consequence potential
- We support risk evaluation for simultaneous operations
- We provide the basis for your emergency response planning zones
- We help you avoid over conservative exclusion zones that limit operational flexibility
- We identify whether high consequence items warrant inherent safer design
- We reduce the cost of consequence modelling errors in your facility siting
- We support risk informed layout optimisation
Codes & standards we work to
Triggers that signal the need
Where Consequence and Dispersion Modelling applies
Wellheads, separators, gas compression, FPSO topsides, produced water systems.
Distillation columns, reactors, heat exchangers, storage spheres, LPG handling.
Cryogenic exchangers, liquefaction trains, BOG compressors, storage and sendout.
Reactive systems, batch reactors, solvent handling, runaway reaction scenarios.
Boilers, HRSGs, steam headers, hydrogen systems, ammonia SCR units.
Sterile vessels, CIP/SIP, pressure fermenters, solvent recovery, spray dryers.
Tangible deliverables
- Consequence modelling report with a scenario register
- Thermal radiation and overpressure output plots
- Toxic dispersion hazard distance tables
- Scenario specific consequence contour maps
- EPA RMP off site consequence analysis documentation
- Sensitivity analysis results
- Hazard range summary for each scenario
- Emergency planning zone recommendations
Ready to start your project?
Speak with our team to scope an engagement tailored to your facility, regulatory context, and lifecycle stage.