rockwood wrote:Reminds me of something we did in science class many years ago.
We heated a one gallon metal gas can (lid off) then removed it from the heat, put the lid on tight and ran under cold water on it. The inside air contraction distorted the can and looked similar to that photo and it only took about one second.
Bingo! The atmospheric pressure collaped the tank due to a vacum inside. Notice the flange at the top with a cap? I told him he could not cap the overflow vent. The group VP wanted a cap and he got it.