Water hammer can work in both directions, and I only discussed one of those in the previous video (https://www.youtube.com/watch?v=xoLmVFAFjn4). Today's episode revisits that demonstration to show how water hammer can form a vacuum pressure in a pipe. Momentum carrying fluid away from a valve wants to keep going even after the valve is closed. This generates a negative pressure than can cause major damage! Watch this video and the entire Practical Engineering catalog ad-free on Nebula: https://go.nebula.tv/practical-engineering -Patreon: http://patreon.com/PracticalEngineering -Website: http://practical.engineering/ Marxist Arrow by Twin Musicom is licensed under a Creative Commons Attribution License Source: https://www.youtube.com/watch?v=rBlLC8TUXP0 Tonic and Energy by Elexive is licensed under a Creative Commons Attribution License Source: https://www.youtube.com/watch?v=U6fBPdu8w9U This video was sponsored by Skillshare.