Atmospheric Pressure Crushes a 55 Gallon Steel Drum
Why Physics Stack Exchange recommends it
Physics Stack Exchange answerers point people to it as a vivid, real-world example of how the pressure difference between inside and outside, created by condensing steam, lets atmospheric pressure crush a container.
Recommended by 1 people across 1 different months, 2015 to 2025.
What it is
A short 2010 demonstration in which a 55 gallon steel drum is crushed by atmospheric pressure after the air inside is replaced by steam and then cooled so the vapour condenses. It is a dramatic version of the classic crushed-can experiment, posted by the channel thechemman.
What people said
Recommends Farcher · 2016-11 · Physics Stack Exchange · on “Why does atmospheric pressure doesn't seem to affect day to day objects?”
Have you never seen the crushed can demonstration? [this video] When the pressure within a can is reduced the net inward force on the can increases until the can collapses. If a vacuum pump is not available the p, as in the video, some water is added to the can and the can heated. The water starts to boil and eventually the can is full of water vapour. At this point the can is sealed and then cooled. The water vapour inside the can condenses and so the pressure inside the can decreases until it is much lower than atmospheric pressure outside. Eventually the pressure difference between the inside and the outside is so great that the inward force on the can causes it to fail. So a can in your your
Cites iantresman · 2015-01 · Physics Stack Exchange · on “How can a small volume of gas balance the pressure exerted by the whole atmosphere?”
It's because the atmosphere exerts a force in all directions. If you think of a thin layer of atmosphere surrounding the balloon, it also pushes against the atmosphere. Of course the air in the balloon is also part of the atmosphere pushing outwards. You could just as easily have put a box on the table, and a lid on top. The air inside the box pushes from below and balances the pressure from above. If you take the air out of the container (eg. condensing steam in a thin metal can), as you have probably seen, the atmosphere crushes it without problem. See " 55 gallon steel drum can crush [this video] "
Cites Rainer Kresken · 2015-10 · Physics Stack Exchange · on “Water vapour collapse”
If you have closed volume of water vapor and make it condense by cooling or raising the pressure, it will collapse instantly. This is demonstrated in the collapsing can experiment [this video] This effect also is the reason for cavitation. But why does it collapse instantly? The condensation of a fraction of the vapor should both lower the pressure in the volume and raise the temperature by releasing some latent heat. Both effects should damp the collapse and not expedite it. Thanks for your help!
Cites Ben51 · 2018-01 · Physics Stack Exchange · on “How did vacuum and temperature play in to a baggie sucked in to a water jug?”
Two factors contribute: thermal expansion of air and water vapor partial pressure. When you fill a jug with hot water, the air above the water quickly warms up. As it slowly cools along with the water, it contracts according to $PV=nRT$. Warm air above warm water includes quite a lot of water molecules. As the air cools, that water vapor condenses (look up Clausius-Clapeyron relation). The liquid water it forms takes up far less space than the vapor. If you boil water in a jug (probably not a plastic one) you can fill the space above the water with nearly 100% water vapor. If you then cap the jug and cool it, the water vapor condenses, and atmospheric pressure can crush the jug to a small fr
Cites mmesser314 · 2025-09 · Physics Stack Exchange · on “Vacuum chamber buckling paradox in ansys in normal vacuum vs Ultra high vacuum?”
In an air filled chamber, air presses very strongly on the inside and outside of the walls. These forces cancel and it is not obvious they are there. It becomes obvious when you remove even some of the air, as in this video [this video] . The pressure on the outside is still ginormous, while the pressure on the inside is just very large. The difference between a good vacuum and an ultrahigh vacuum doesn't matter. The pressure on the inside is tiny vs really tiny. It is the pressure on the outside that makes it collapse.