55 Gallon Drum Collapse from Vacuum

When the air inside a 55 gallon steel drum is pumped out, we see the weight of the atmosphere push inward with 101 kPa of pressure.

The top and bottom of the drum has a radius of about 30 centimeters, and it is about 1 meter tall. This means the atmosphere pushes down on the top of the drum with about 6,500 pounds of force! We leave the calculation of the force on the sides as an exercise to the student.

We pump on the drum with a Varian SD-200 vacuum pump. Usually the initial collapse will occur after a minute or two. The drum seen here actually underwent initial collapse after 35 seconds of pumping; the footage was edited to make it more watchable.

For more details on our setup, see https://sciencedemonstrations.fas.harvard.edu/presentations/55-gallon-drum