Which statement describes a primary storage tank design feature?

Which statement describes a primary storage tank design feature?

• A. Internal and external floating roof tanks
• B. Concrete, steel welded, collapsible
• C. Glass-lined pressure tanks
• D. Wooden casks

Answer: (A)

Floating roofs are a key design feature of primary storage tanks because they minimize vapor loss by reducing the space above the stored liquid. An external floating roof sits directly on the liquid surface and moves with changing liquid levels, forming a seal at the edges to limit vapors escaping. An internal floating roof is located inside the fixed roof and also floats on the liquid surface, providing a variable barrier that reduces evaporation. Together, these designs help control emissions and improve safety and efficiency for storing volatile liquids. Other tank types listed aren’t typical primary storage designs for large-volume storage. Concrete, steel welded, collapsible tanks describe structural approaches not focused on vapor control. Glass-lined pressure tanks are designed for high-pressure service, not open-pond storage. Wooden casks are antiquated and not used for modern bulk liquid storage.

Floating roofs are a key design feature of primary storage tanks because they minimize vapor loss by reducing the space above the stored liquid. An external floating roof sits directly on the liquid surface and moves with changing liquid levels, forming a seal at the edges to limit vapors escaping. An internal floating roof is located inside the fixed roof and also floats on the liquid surface, providing a variable barrier that reduces evaporation. Together, these designs help control emissions and improve safety and efficiency for storing volatile liquids.

Other tank types listed aren’t typical primary storage designs for large-volume storage. Concrete, steel welded, collapsible tanks describe structural approaches not focused on vapor control. Glass-lined pressure tanks are designed for high-pressure service, not open-pond storage. Wooden casks are antiquated and not used for modern bulk liquid storage.