Technical documentation and software quality assurance for project ...

Martin Goodrich Baker Engineering and Risk Consultants
Greg Jackson University of Maryland
Tom Spicer University of Arkansas
Doug Walton National Institute of Science and Technology
Kin Wong Department of Transportation
Special Training Requirements/Certification:
There are no special additional requirements or certification required to use the new fire
and explosion option scenarios in ALOHA. However, certain terminology peculiar to
these specific scenarios will be different from those involving the toxic gas model runs.
It is recommended that anyone new to fire and explosives forecasting review the user
documentation and become familiar with the example problems. In particular, hazards
now include overpressure and thermal radiation risk, as opposed to toxic chemical
concentrations.
Data Sources:
Eagle-ALOHA uses the existing ALOHA/CAMEO chemical data sources with the
exception of information on fuel reactivity. For a small set of chemicals, ALOHA uses
values for fuel reactivity referenced in Appendix C of John L. Woodward, Estimating the
Flammable Mass of a Vapor Cloud, published by American Institute of Chemical
Engineers, 1998. For all other flammable chemicals, ALOHA assigns medium reactivity.
Program structure:
TECHNICAL DOCUMENTATION
Generally, the project only allows the new scenarios for that subset of existing ALOHA
chemicals that are classified by the National Fire Protection Association's Fire Protection
Guide to Hazardous Materials as a category 3 or 4 flammable hazard. This includes
flammable gases and liquids with a flash point below 100 °F. The model will allow the
user to select combustible liquids (category 1 and 2 flammable hazard) but may, for lowtemperature
scenarios, provide a warning to the user that the chemical may not burn at
the user-specified temperature.
Figure 1 shows the possible scenarios for a chemical release from a tank, pool, or
pipeline with an ignition source present at the beginning of the release. For a delayed
ignition, there may be time for a flammable cloud to develop, thereby creating the
potential for a flashfire or explosion. For a pool release, there is also the potential for a
flashback causing a subsequent pool fire. This is not modeled in this project.
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