GexCon AS

FLACS Software


FLACS is the industry standard for CFD explosion modeling and one of the best validated tools for modeling flammable and toxic releases in the technical safety context.

FLACS is a comprehensive, yet easy to use, software tool for modelling (dispersion and explosion) consequences in full 3D for all typical flammable and toxic release scenarios. It is used extensively in the Oil and Gas and Process industries and also increasingly in the nuclear industry, in facilities with dust explosion potential and many other fields. By modelling with CFD (Computation Fluid Dynamics) in full 3D it is possible to predict consequences much more accurately and to include the effect of all contributing and mitigating effects (such as confinement and congestion due to real geometry, ventilation, deluge). A better understanding and higher accuracy of results not only contributes to raising the true level of safety but also allows designers to choose truly effective design option and mitigation measures and thereby improving both safety and cost effectiveness way.

FLACS is a consequence modelling software tool which provides you with:

  • Integrated explosion and dispersion modelling capabilities
  • Consequence modelling in Full-3D
  • Geometry import (Microstation dgn v7/8 format, PDMS(via dgn), PDS, AutoReagas)
  • Efficient manual editing of geometry
  • 2-phase (flashing liquid) modelling
  • Gas mixtures
  • Transient (time dependent) modelling
  • Include effects of mitigation and preventive measures
  • Accurate and extensively validated results
  • Various different options for viewing results (2D, 3D, animations, text file output)
  • A better understanding of the phenomena and results
  • Comprehensive user guidelines based on extensive validation against experiments

FLACS is used extensively for the following applications:

  • Offshore Explosion study (both risk based and deterministic)
  • Onshore building risk assessments (i.e. control room or temporary buildings)
  • Gas detector optimisation
  • Toxic dispersion calculations
  • Dust Explosions (with FLACS-DustEx)
  • Accident investigation (FLACS was used for investigating many different accidents such as Piper Alpha, Buncefield, Deep water Horizon, Texas City Refinery, TWA 800 aircraft accident)

FLACS is used extensively by:

  • Almost all major Oil and Gas companies
  • Technical Safety consultants
  • Engineering contractors
  • Research institutes (including nuclear)
  • Universities

The FLACS suite of software is based on the CFD technology developed at Gexcon (CMR/CMI) since 1980. FLACS has, since the first version was released in 1986, been a world leader within gas explosion models. This is due to a competent modelling team, good experimental facilities and understanding, stimulating sponsor companies and a large in-house user group of consultants.
The FLACS standard package can handle explosion, dispersion, ventilation, mitigation and pool modelling. It is also possible to buy or lease individual modules – at a significantly lower price than for FLACS standard package.

This is a subset of the FLACS simulator that has the capabilities of the FLACS simulator in the area of dispersion and ventilation, but where the explosion capabilities are deactivated. Due to the ability to represent detailed geometries with the distributed porosity concept, the dispersion capabilities of FLACS have proven particularly powerful in calculating release scenarios in process areas where the density of objects and pipes is high. FLACS has been extensively validated against large-scale realistic release and explosion tests performed at Gexcon and full-scale experiments carried out at the Advantica test site Spadeadam in a 2600 m3 semi-confined model of an offshore module.


Since FLACS is a dedicated explosion simulator, the dispersion models are highly suitable in calculating explosion cloud sizes and use in explosion risk assessments. Recent work has addressed the ability to simulate toxic release scenarios onshore, in which representation of terrain and turbulent wind profiles are important. Models for release and dispersion of aerosols are also under development. These can be added as a complementary option.
The price of FLACS-DISPERSION will be significantly lower than for the FLACS standard package.

Capabilities include:

  • Geometry import from CAD
  • Various gases (More than 10 + user-defined) and mixtures of these
  • Wind boundary conditions with wind profiles
  • Effect of water deluge on dispersion
  • Efficient pre-processing, reasonable simulation times
  • Export of gas clouds to explosion calculations (FLACS)
  • Data to estimate transient ignition probabilities and cloud sizes
  • Local gas concentrations and accumulated cloud estimates
  • 2D and 3D field plots with various variables
  • Automatic generation of mpg-videos from post-processor
  • Extensive validation (Phase 3B, Dispersion JIP, GSP, Licorefla, SMEDIS)
  • And more...

The tool will be suitable for companies interested in a well-developed and validated dispersion tool suitable for representing realistic geometry densities efficiently. Also companies that would use other tools than FLACS for explosion calculations could benefit from using FLACS-DISPERSION to estimate likely gas cloud sizes in a process area.

FLACS-Gasex is a subset of the FLACS simulator that has the capabilities of the FLACS simulator in the area of explosion, but where the ventilation and dispersion capabilities is removed. In the gas explosion area FLACS-Gasex has more extensive capabilities and applicability than its competitors and has the same validity as FLACS.
The price of FLACS-Gasex will be significantly lower than 
for the FLACS standard package.

Capabilities include:

  • Geometry import from CAD
  • Import of dispersed gas clouds (FLACS and a few more CFD-codes)
  • Well validated CFD-explosion simulator
  • Efficient pre-processing and simulation times
  • Various gases (More than 10 + user-defined) and mixtures of these
  • Fuel lean, stoichiometric and rich mixtures with air
  • Effect of water deluge and dilution by inert gas
  • Effect of increased oxygen content in air
  • Non-standard temperature and initial pressure
  • Initial turbulence
  • Rupture discs, relief panels and simplified wall failures
  • Blast propagation (multiblock concept / non-reflecting boundary condition)
  • Local pressures and average wall pressures (and other variables)
  • 2D and 3D field plots of various variables
  • Automatic generation of mpg-videos from post-processor
  • And more

Area of use:

  • Offshore installations (natural gas mixtures)
  • Onshore plants (natural gas, ethylene/propylene, hydrogen/synthesis gas)
  • Explosions in factory buildings
  • Domestic explosions (natural gas, propane, butane, CO)
  • Explosions inside process equipment / exhaust systems
  • Tunnel explosions

FLACS-Hydrogen has the same capabilities as the 
FLACS standard package with regard to hydrogen dispersion and explosions, or situations in where hydrogen dominates the gas mixture. This version of FLACS can be useful in risk evaluations in connection with the use of hydrogen as an energy carrier, for nuclear plants, in chemical factories, synthesis gas (gas to liquid processes) and microprocessor factories (on request Silane SiH4 will also be possible to model).

With FLACS-Hydrogen one can simulate and evaluate to what extent a leak scenario may produce flammable gas clouds in a given scenario, and to what extent the flammable gas clouds may represent a significant risk. FLACS has been able to simulate hydrogen explosions since before 1990. In recent years, a number of research projects have been considered the validity of FLACS in the area of hydrogen explosions.

The price of FLACS-Hydrogen will be significantly lower than 
for the FLACS standard package as its use is limited to gas mixtures dominated by hydrogen.

Capabilities include:

  • Manual geometry definition or import from CAD
  • Efficient pre-processing, reasonable simulation times
  • Dispersion of hydrogen dominated mixtures from leak
  • Explosion of dispersed or pre-defined gas clouds
  • Pressure curves at various locations and walls (averaged)
  • Pressure relief panels with inertia can represent collapsing walls
  • 2D and 3D field plots of various variables (flame and maximum pressure)
  • Automatic generation of mpg-videos from post-processor

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