Category: General

The vessel or pool releasing a hazardous chemical into the atmosphere

The distance above the ground at which a chemical is being released.

Either the rate the chemical enters the atmosphere or the burn rate, depending on the scenario. A chemical may escape very quickly (so that source strength is high), as when a pressurized container is ruptured, or more slowly over a longer period of time (so that source strength is low), as when a puddle evaporates

Heat released during a fire and explosion that may pose a hazard to people and structures. The effects people experience will depend on both the level of thermal radiation and the length of time they are exposed to it.

The ratio of the amount of water vapor that the air contains to the maximum amount of water vapor that it could hold at the ambient temperature and pressure. Relative humidity is expressed as a percentage. When relative humidity is 50%, the air contains one half as much water vapor as it could potentially hold.

A pool fire occurs when a flammable liquid forms a puddle on the ground and catches on fire. Thermal radiation is the primary hazard associated with a pool fire. Other potential pool fire hazards include smoke, toxic byproducts from the fire, and secondary fires and explosions in the surrounding area

At equilibrium, molecules move from the liquid to the gas phase at the same rate as they return to the liquid from the gas phase. In liquids that are mixtures of chemicals, each component vaporizes (evaporates) at its own characteristic rate. The partial pressure of a chemical in a mixture is a measure of the concentration of that chemical’s gas-phase molecules in the air directly in contact with the liquid. In most actual cases equilibrium is not reached so the partial pressure represents the limiting value for chemical concentration in the air.

Refers to the sudden onset of a pressure wave after an explosion. This pressure wave is caused by the energy released in the initial explosion—the bigger the initial explosion, the more damaging the pressure wave.