Which of the following is NOT a dispersion pattern for pressure containers?

• A. Hemispheric
• B. Cloud
• C. Plume
• D. Cone

Answer: (B)

When a pressure container vents, the released material behaves like a high-energy jet whose shape is strongly influenced by wind and the source geometry. The near-field forms shape patterns that reflect that physics: if the release expands almost equally in all directions, you get a hemispherical pattern; if the gas escapes through a small opening and fans out, it forms a cone; and as wind carries the release, it can stretch into a plume downwind. A cloud, by contrast, implies a more diffuse, fog-like spread from ongoing evaporation or a broad, slow-forming vapor, not the rapid, directional jet behavior typical of a ruptured pressurized vessel. For that reason, cloud is not considered a standard dispersion pattern for pressure-container releases.