the flammable vapour in the cloud is 90 tonnes (U.S. EPA, b). The threshold is estimated by modeling with Process Hazard Analysis Software The equation for estimating the evaporation rate of a liquid from a pool is . Flammable Gases and Office of Prevention and Toxic Substance (). EPA R KEY WORDS: Acute hazards; environmental equity; GIS; worst-case exposure. 1. Flammable gases and liquids and their hazards (EPA R-. ). Background: Section (r) of the Clean Air Act (CAA) requires facilities that have threshold installation: a hazard assessment, a management program, . Agency (EPA) an RMP that summarizes their Risk Management Program Gases handled as refrigerated liquids at EPA R

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WHAZAN modeling was also carried out for the ten chemicals shown in Exhibit 11 using additional meteorological conditions of wind speed of 1. He concludes that since the flamnable.gases outside of the cloud exposed to intense thermal radiation is liquidds, no fatalities due to thermal radiation can be expected outside the area engulfed in flame.

Gasoline is not regulated as a special case under any of the regulations or codes mentioned above. The diameter of the pool is calculated from the volume of propane in the pool, assuming the pool spreads out to a thickness of.

In cases where there were sufficient data, modeling was carried out using reported data from selected incidents as model input The modeling effort and the results obtained are discussed in Section 9. The procedures and examples in this module have illustrated various modeling techniques that can be used to predict areas of possible impact associated with hazardous material accidents.

The classifications are designed to give “a general idea of the inherent hazards of any material and the order of severity of these hazards as they relate to fire prevention, exposure and control” NFPA In an official inquiry to the Agency inSenator Frank Lautenburg also noted concern for hazards other than toxicity and asked that EPA focus on other hazards.

The purpose of the list was to identify those substances that, if accidentally released, could cause death or serious irreversible health effects from toxicity off-site after a short exposure. The data for a specific quantity and hazard criteria level are fairly consistent from chemical to chemical.


Brief Records : EPA National Library Catalog

The hazards of projectiles resulting from explosions are also discussed. Note also that the quantity in the cloud is considerably smaller than the quantity released; i. The most recent and complete data base records for OSHA inspections fiscal year were examined for this analysis. If the dominant means of transfer of heat to the pool is wind, the previous equation is appropriate.

Varying the meteorological conditions appeared to have no effect; results obtained were identical to the results obtained using moderate meteorological conditions, indicating that meteorological conditions would be expected to have little impact on the consequences of BLEVEs.

Pool fire diameters can also be calculated for surfaces with friction, and with no friction. Guidelines for peak overpressures required to produce property damage are presented in Exhibit C The explosion data was just outside this predicted range. Delayed ignition might allow more flammable vapor be released, and the vapor cloud might travel further off-site, possibly increasing the potential for off-site damage.

The user can add chemicals and properties to the data base. Propylene liquefied under pressure K, It has also been assumed that the optimum orientation between observer and flame that yields a maximum view factor prevails.

Assume the reactor is constructed of carbon steel and that the fracture is ductile F Oleum a solution of sulfur trioxide in sulfuric acid also is discussed. Levels below the LFL are used to account for variability within the cloud from its edge to its center and inaccuracies in dispersion modeling.

For modeling purposes, several hazard criteria levels of overpressure, thermal radiation, or concentration associated with each type of accident consequence were used for modeling.

Some damage to house ceilings. Neutrally buoyant and dense gases are dispersed in different ways when they are released.

The WHAZAN buoyant plume dispersion model was used to estimate the greatest downwind distances at which a flame will move through a flammable vapor cloud. Scenario 2 The 744-r-9-4002 of the vessel fragment Af is given in Scenario 2 as 10 ft2 or 0. A major consideration in this work was the need to express the hazards of flammable chemicals as correctly and simply as possible for use by risk managers.


The explosion in Canada involving 1, pounds may be an anomaly since it was a partially confined vapor cloud explosion. The evaporation rate at the minimum pool thickness is calculated as follows: The most conservative assumption would be to assume the entire quantity is in the cloud; such an occurrence seems very unlikely, however.

It is dependent on the quantity of chemical released, the nature of the release scenario i. Offshore and marine transportation incidents are excluded.

Flammable Gases and Liquids and Their Hazards

Modeling indicates that pool fires are less hazardous than vapor cloud fires and explosions, based on the distance results. If the gas liquefied by refrigeration would form a pool one centimeter 0. Exhibit 14 presents WHAZAN modeling results for BLEVEs of gases ethylene, propylene, propane, and n-butane and for pentane, a volatile liquid assumed to be stored under pressure, for release quantities of 1, pounds topounds.

Gases liquefied by refrigeration that would form a pool one centimeter 0. If ammonia is liquefied by refrigeration alone, use Figureeven if the duration of the release is greater than 10 minutes.

Estimate fragment velocity and distance. Quantities released displayed on the graph range from 1, to 50, pounds. The indicative criteria related to flammability are discussed in Appendix A. High overpressure levels can liqukds death or injury as a direct result of an explosion; such effects generally occur close to the site of an explosion.

A spark ignited the fuel-air mixture, ans killing four of the van’s occupants; two occupants later died of injuries sustained, while the other two were severely burned. These factors may be used to estimate an average release rate for the hazardous substances from a pool formed by a spill of solution. Twenty to 25 minutes later, the cargo tank exploded, burning or otherwise injuring 28 people, one of whom was feet away from the explosion.

Unmitigated Releases of Toxic Liquids. In planning with regard to injury to personnel, the following guidelines have been recommended Brasie and Simpson