Which confined space is considered to be an open top enclosure?

Which confined space is considered to be an open top enclosure?

• A. Tank
• B. Vault
• C. Duct
• D. Pit

Answer: (D)

Open-top enclosure means a confined space that is enclosed on the sides and bottom but has an opening at the top, not covered. A pit fits this description: it’s a hole in the ground with no lid, so the space is open to the surface. A tank is usually closed at the top with a cover, a vault is sealed with a lid, and a duct is a conduit that’s enclosed along its length (air enters mainly through ends rather than through an open top). So the space that’s open to the atmosphere at the top is the pit.

Open-top enclosure means a confined space that is enclosed on the sides and bottom but has an opening at the top, not covered. A pit fits this description: it’s a hole in the ground with no lid, so the space is open to the surface. A tank is usually closed at the top with a cover, a vault is sealed with a lid, and a duct is a conduit that’s enclosed along its length (air enters mainly through ends rather than through an open top). So the space that’s open to the atmosphere at the top is the pit.