Crushing of Steel Drum

Dan Stamm, a physics teacher at Campbell High School in Smyrna, GA constructed a platform for heating water in a steel drum. The drums used had a surface area of about 3000 square inches. The force of one atmosphere of pressure on that area is about 44,000 lbs or 22 tons! Nevertheless, such cans can be made of reasonably thin steel because the same force normally acts outward from the inside of the vessel.

The procedure involved pouring about a gallon of water into the drum (just enough to cover the bottom) and and heating it over a propane burner for 15 to 30 minutes. The water is brought to the boiling point where its vapor pressure is equal to atmospheric pressure. The vapor will then push most of the air out of the can. The can is then sealed as the heat is removed. If the drum is cooled quickly, the sudden drop in vapor pressure will result in enough net inward pressure to crush the can. 该过程涉及将约一加仑的水倒入桶中（只需覆盖底部即可），然后在丙烷燃烧器上加热15到30分钟。水被加热至沸点，此时其蒸汽压等于大气压。蒸汽将推动罐内大部分空气排出。当热量移除时，将密封罐体。如果桶迅速冷却，蒸汽压的突然下降将导致足够的净内压，使罐体被压扁。 丹·斯塔姆是佐治亚州斯米纳市卡姆皮尔高中的一名物理老师，他设计了一个用于加热水的平台，使用的是钢桶。这些钢桶的表面积约为3000平方英寸。一个大气压对这个面积的力约为44,000磅或22吨！然而，这样的桶可以用相对薄的钢制成，因为同样的力通常作用于容器的内侧向外。 Load Movie 1 电影1 Movie 2 电影2 Movie 3 电影3 Movie 4 电影4 加载

Boiling Water to Produce a Vacuum

Drum crushing experiment" 鼓式破碎实验

Boiling water in a steel drum drives the air out. Since the definition of the boiling point is the temperature at which the vapor pressure is equal to atmospheric pressure, it follows that boiling water for a period of time will force most of the air out of the vessel. If the drum is then sealed, then the pressure inside is just the vapor pressure of the water. This vapor pressure drops precipitously as the vapor is cooled below 100 degrees C. Dropping the temperature to 60 degrees C lowers the vapor pressure to about 20% of atmospheric. The drums used had a surface area of about 3000 square inches. The force of one atmosphere of pressure on that area is about 44,000 lbs or 22 tons! Even the modest cooling to 60 degrees C would result in an inward crushing force of over 17 tons! Sudden cooling to 20 degrees C would lower the pressure to just over 2% of an atmosphere and provide over 21 tons of crushing force. 钢 drum 中的沸腾水会将空气排出。由于沸点的定义是蒸汽压等于大气压的温度，因此在一段时间内沸腾水会使容器中大部分空气被排出。如果然后将 drum 密封，那么内部压力就只是水的蒸汽压。当蒸汽冷却到低于 100 摄氏度时，蒸汽压会急剧下降。将温度降至 60 摄氏度时，蒸汽压会降至约大气压的 20%。所用的 drum 表面积约为 3000 平方英寸。一个大气压在这面积上的力约为 44,000 磅或 22 吨！即使冷却到 60 摄氏度，也会产生超过 17 吨的内挤压力！突然冷却到 20 摄氏度时，压力会降至略高于大气压的 2%，并提供超过 21 吨的挤压力。