How a Multi-Size Pipe Plug Holds Back a Sewer: Pressure, Area and Grip
A short explanation of F = p × A, pipe-plug grip and how one multi-size plug seals a range of sewer pipe sizes.
Application Overview
This is an excerpt from the full explainer. The figures use the published MS 150-300 example and F = p × A. Confirm the model, measured pipe size and back-pressure rating for each project.
English transcript
Based on YouTube's automatic captions, with sound tags removed and obvious transcription errors corrected. Refer to the video and product documentation for technical details.
This rubber plug weighs 2.5 kg. Yet in a 300 mm sewer, it can hold back a push of about 700 kg. So, how does a rubber plug do that? Let's take it apart. Push in a plug, inflate it, and the flow stops. But the water keeps building up behind it. That buildup is back pressure, and it pushes on every square centimeter of the plug. Here's the key idea. Force equals pressure times area. One bar is 10 newtons on every square centimeter. A 300 mm pipe has about 700 square cm of face. So, one bar of back pressure pushes with about 7,000 newtons. That's roughly 700 kg. Now, double the pipe diameter. The face area goes up four times and so does the force at the same pressure. Watch the full explainer on our channel.
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