AI Summary
This video explains the mechanics behind self-siphoning devices used in urinals to flush periodically. It highlights a common flaw in automatic siphons when water fills slowly and presents a clever design that overcomes it using an inner chamber and small air inlet.
Chapters
A simple automatic siphon empties a container when water rises above its top, but fails when filled slowly due to lack of a seal.
When filling slowly, the siphon doesn't prime because air can escape before a seal forms, causing the container to empty slowly.
In public restrooms, urinals use siphons to flush periodically, and they are all connected to a common system to synchronize flushes.
The mechanism solves the slow-fill problem by using a thinner inner chamber and a small hole that traps air, ensuring a seal even at low flow rates.
Using slow motion footage, the video shows how the inner chamber fills, air escapes through a hole, and water levels equalize, leading to siphon initiation.
Initial test had a flaw where water level didn't change; adjustments were made to the heights of the channels to achieve proper operation.
A narrow channel allows water to slowly fill, and when it tips over, a small hole prevents backflow, causing the main siphon to prime via trapped air.
The 3D version includes a box, copper pipe, and U-bend. The primer siphon feeds into the main siphon, ensuring reliable periodic flushing.
The video successfully demystifies a clever mechanical timer that uses water pressure to flush urinals periodically, showcasing an elegant solution to a common engineering problem.
Mentioned in this Video
Study Flashcards (3)
What is the main flaw of a simple automatic siphon?
easy
Click to reveal answer
What is the main flaw of a simple automatic siphon?
It fails to prime when the container is filled slowly.
00:17
How does the inner chamber design overcome the slow fill problem?
medium
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How does the inner chamber design overcome the slow fill problem?
A narrow channel and small hole trap air, creating a seal even when filling slowly.
02:11
What happens if the hole for air escape is too large?
hard
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What happens if the hole for air escape is too large?
Air would bubble through, and water would trickle without forming a proper seal.
05:24
💡 Key Takeaways
Slow Filling Reveals Flaw
Demonstrates a real-world limitation of a simple siphon that many might not consider.
00:59Clever Engineering Solution
Shows how a simple addition of an inner chamber and small hole solves a significant problem.
02:11From 2D to 3D
The transition from theoretical model to actual working device illustrates practical engineering.
07:08Full Transcript
[00:01] It's an example of an automatic siphon but I am already a huge fan of automatic siphons. so when the water level rises above the top of the siphon,
[00:17] and the container empties itself. to add binary numbers together, for example. that automatic siphons have a huge flaw.
[00:31] Instead of the siphon priming, no seal is created, narrower so that even if you're filling
[00:46] will ensure that there is a seal out of the container very slowly. that you fill very slowly,
[00:59] You might think that's a very niche requirement, Look, I'm very slowly filling this container, suddenly the whole thing starts to empty very quickly
[01:13] and what you're looking at here is a urinal siphon. you'll be familiar with that moment suddenly start flushing at the same time.
[01:26] such a poorly maintained amenity for this shot. whilst I was filming a urinal until it did the flush thing, This simultaneous flushing thing
[01:41] but the idea is instead of each urinal they're all connected to the same system And if you want a container to empty periodically,
[01:56] seems like the perfect mechanism to use. so we turn down the flow of water into the container. and we can't just make the siphon channel narrower
[02:11] So we need some way of getting a good seal even when the container is being filled slowly, and that's exactly what this mechanism achieves
[02:23] Just a quick note on the 2Dness of this. 2D versions of things, would sit in the middle of the container.
[02:37] into two regions that aren't connected. to one side of the container instead of in the middle. about three different siphons all working together
[02:52] because they'll block each other. You see that around the back, and then this kind of thinner inner chamber
[03:06] So strictly speaking, this isn't 2D. are 2D because of the universe we live in, this video would've been much harder to make
[03:20] if it wasn't for this video by Mr. Matt and Mr. Chay. Link in the card and the description to that video To explain how it works I've got this slow motion footage,
[03:33] and pause it in different places but I'll show it all the way through at normal speed As the container fills up,
[03:47] That's because air is able to escape but ultimately via this hole here. of that inner chamber,
[03:59] so the water level rises through there as well. the reason you are seeing water here and you can see that by looking around the back.
[04:15] The water continues to rise as before, reaches the bottom of this channel. in the main siphon chamber stops rising.
[04:28] for the air inside the main siphon chamber But this surface and this surface so we should expect them to match the level
[04:41] of the water in the main container. If there wasn't a plug of water here, would always be able to escape
[04:54] and that's happening in such a way matches the difference in height between here and here between the inside of the siphon chamber
[05:09] In Mr. Matt and Mr. Chay's animation, and the water level doesn't change that wasn't right after some initial test runs.
[05:24] otherwise you'd get air bubbling through with water trickling over the inlet. and the height of this two close together.
[05:39] the height inside the main part of the siphon chamber But actually because the water level is going down here, So in this failed version,
[05:55] as soon as the water starts tipping over the edge, where the water coming in matches the water going out But anyway, the really clever part is just coming up.
[06:08] and because this channel is so narrow, of water coming into the system This hole is small enough that water can't get back in
[06:23] and so the level of the water And because the water level has gone down, and the air that was trapped inside the siphon chamber
[06:38] And crucially by this point, is all the way up here. means that the level of water in the siphon chamber
[06:51] has a way to get out is enough to create a seal in this tube here, and so the main siphon is initiated.
[07:08] Look, this was one of my earlier designs. and air inlet tube could be vented but that just means that the main siphon chamber
[07:22] once that smaller inner siphon is activated. the water level inside drops down and the siphon breaks.
[07:36] those two channels merge with the main siphon here that route is blocked for the passage of air coming in. to be able to get out of the siphon chamber
[07:50] and over the main siphon channel. we need to stop air from being able to get back in and priming siphon join the main siphon channel here,
[08:07] to the real-world 3D device. So this siphon sits inside the system
[08:19] Around the base, there's this gap you can see here and I've loosened it already so we can take it off. this kind of box bit here, this open box.
[08:34] that I've created with the white background here. so you can see what's going on there. So look, that's where the air can get in,
[08:49] That sits at the bottom in there has to go up through there And then the copper pipe, this one here,
[09:07] You'll notice that the funny box bit That's equivalent to the little hole and this is the main siphon,
[09:21] This U-bend bit here is inside. and you can see those two holes there.
[09:35] and the exit for the primer siphon, they both feed into that final U-bend part there. As promised, here's the whole sequence at normal speed.
[09:49] (upbeat rock music)
[10:25] (light jazz music)
[10:43] because I needed light coming from the back, to get light coming through that blue liquid, and that needs to be lit from the front.
[10:56] and I'm playing around with frame rate between point-and-shoot photography and DSLR photography You could use a bread machine, it's dead easy,
[11:11] You don't have as much control over things and bake in the oven. because it's just such an unbelievably smooth transition
[11:24] another example is razor blades. And that's by design without worrying about the position of the blades
[11:36] or the point-and-click camera, there are trade-offs. and just try shaving if you've let your beard
[11:48] Before the bread machine, there was oven there was the safety razor The Henson a AR13 is friendly to your skin by default.
[12:03] extends just 30 microns from the shave plane by following the contours of your face. had that simple skill for his entire adult life
[12:15] since Henson started sponsoring my videos. that I've been trying to do recently. for a precision engineered handle from a company
[12:27] and then that's yours for life. If you're interested, go to hensonshaving.com/stevemould to get 100 free blades with the purchase of your AL13 razor.
[12:43] I hope you enjoyed this video. (light bright music)
