VAPOR CLOUD EXPLOSION STUDY

The study was divided into five phases: Phase I included an analytical evaluation of the possible magnitude and damage potential of a spill of LNG; Phase II consisted of shock tube tests and tests in thin film hemispheres to evaluate potential transition from deflagration to detonation in unconfined clouds of flammable gases; Phase III included a series of spills of LNG onto water to determine pool size, flame height, flame radiation, vapor dispersion, and flame speed through a vapor cloud; Phase IV consisted of a series of spills of LPG and gasoline onto water to provide direct comparison of the hazard potential of LNG, LPG, and gasoline; Phase V consisted of additional thin film hemisphere tests to determine whether a detonation initiated by a high explosive charge or a detonation exiting a tube could be sustained within an unconfined vapor cloud. Preliminary analysis of the data indicate that (1) transition from deflagration to detonation in unconfined vapor clouds does not appear to occur; (2) flame heights observed during LNG pool fires are taller than predicted; (3) LNG pool fires do not spread over the entire pool surface; (4) LNG is extremely difficult to detonate; (5) due to high flame speeds, fires on LPG pools tend to cover the entire pool surface; and (6) the emissive power of the flame in both LNG vapor and pool fires is higher than expected. The results of this study will be used in updating the spill models contained within the USCG Chemical Hazards Response Information System (CHRIS) and the Population Vulnerability Model (PVM). This study was partially funded by the Energy Research and Development Administration, The American Gas Association, The Office of Pipeline Safety Operations, and the U.S. Department of Energy.