What type of construction can nearly ensure airtight conditions for division walls?

Tangent tube construction is known for its design that allows for minimal air leakage, making it particularly effective in achieving airtight conditions for division walls. This construction method utilizes the close alignment and contact of the tubes, which helps to prevent the passage of air or gas through the wall. The design typically involves tubes arranged tangent to each other, providing a greater seal and reducing potential gaps that could compromise air-tightness.

In contrast, the other construction types do not achieve the same level of airtightness. Separate tube construction may have spaces between the tubes that could allow for air movement, while open-ended construction lacks the sealing properties necessary for airtightness. Sealed unit construction, while aimed at preventing air exchange, may not optimize the structural contact and alignment found in tangent tube construction.

Overall, tangent tube construction's specific design features contribute significantly to its capability of creating airtight divisions, making it the most suitable choice among the options provided.