Which is the best way to verify flatness when starting installation on vertical vessel?

• A. With a level
• B. With a plumb bob
• C. With a ruler
• D. With a tape measure

Answer: (A)

Verifying flatness means confirming that the surface lies in a single, horizontal plane. When starting installation on a vertical vessel, you need the base surface to be truly level so subsequent components sit correctly and seals or fits align across the area. A level is designed to compare the surface against the horizontal reference using gravity, giving immediate feedback across the whole surface as you check at multiple points. A plumb bob looks at vertical alignment, not horizontal flatness, so it doesn’t address the same concern. A ruler or tape measure can only check distances or a single line, and won’t reliably reveal bowing or unevenness over the full area. So, using a level provides the most accurate assessment of flatness for this situation.