MattD Posted February 9 Share Posted February 9 I understand that the 'correct' way to turn a drain through 90° at an inspection chamber (IC) is to connect a 45° elbow at either end of the IC. The diagram below comes from here (I have added the red arrows): As a total newcomer to the field, I'm struggling to understand why the preferred method isn't to simply connect the incoming pipe into the inlet which already enters at 90° to the outlet, i.e following the red arrows. That would avoid the need for the two additional 45° elbows, and presumably would make rodding easier too. I must be missing something. Can anyone explain why the above is preferred? Link to comment Share on other sites More sharing options...
ETC Posted February 9 Share Posted February 9 Because it keeps everything in the main channel as it comes around a corner. Link to comment Share on other sites More sharing options...
MattD Posted February 9 Author Share Posted February 9 Thanks @ETC. But why does that matter? I guess it has to do with efficiency of the flow and/or reducing the risk of the IC silting up? But if all of the inlets were in use then wouldn't two of them have to bend by 90° anyway..? Link to comment Share on other sites More sharing options...
ProDave Posted February 9 Share Posted February 9 I used the 90 degree input on all of mine. BC were happy, and it meant no bends in line just straight runs. Link to comment Share on other sites More sharing options...
saveasteading Posted February 9 Share Posted February 9 Generally there is a drop in level from the secondary inlets down to the main channel. The through channel works better and you don't lose height along the main run, and sometimes that matters, to maintain gradient. As a minor advantage, 2 x 45° allows a little more adjustment than 1 x 90°. Link to comment Share on other sites More sharing options...
Ian Posted February 10 Share Posted February 10 (edited) I had to relay one of my manholes a year after completion because it hadn’t been installed properly (ie it wasn’t done as shown in your diagram) Some solids were always being left behind in the area next to the capped-off lower channel which was then leading to smells. Edited February 10 by Ian Link to comment Share on other sites More sharing options...
Crunchynut Posted February 10 Share Posted February 10 (edited) You want to have a flow through the main low level channel to ‘catch’ and ‘sweep away’ anything that has dropped in from the side entry channels. If there is no main channel flow then bend at entry to the IC so you can use the main channel and the drop is avoided. Edited February 10 by Crunchynut Link to comment Share on other sites More sharing options...
ToughButterCup Posted February 10 Share Posted February 10 Our BC explained that the arrangement (as outlined above) is to ' soften the turn ' by making the flow turn 45 degrees each time. She told me the flow speed would be slowed down more by a single 90 degree turn. I've always wondered if there is any truth to that. Anyone know ? @SteamyTea @Iceverge, @MikeSharp01 , @saveasteading? Yes, I would have asked the same question if the BCO had been male. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted February 10 Share Posted February 10 Our BC wanted the sweeps kept shallow so we do have some interesting pipework leading up to the chamber to avoid a 90 bend in the chamber. I have colleagues at the Uni doing some research work with one of the big pipe manufacturers and they are building a long drop (20m) to rest bend then into chamber all in clear plastic instrumented to death to research how these flows work, the forces involved and the challenges of transporting the stuff that regularly gets flushed that probably shouldn't. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 10 Share Posted February 10 10 minutes ago, MikeSharp01 said: I have colleagues at the Uni doing some research work with one of the big pipe manufacturers and they are building a long drop (20m) to rest bend then into chamber all in clear plastic instrumented to death to research how these flows work, the forces involved and the challenges of transporting the stuff that regularly gets flushed that probably shouldn't. I am looking forward to the Christmas video. 20 minutes ago, ToughButterCup said: soften the turn Link to comment Share on other sites More sharing options...
saveasteading Posted February 10 Share Posted February 10 50 minutes ago, ToughButterCup said: there is any truth to that. Anyone know ? That's exactly right. Water and contents going round a 90° bend encounters turbulence. That slows flow, especially of solids. Esp to be avoided for gentler slopes. Free water is also likely to run past the solids. Think bobsleigh going round a sharp bend. If it slings up high it is taking a longer route and slowing. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 10 Share Posted February 10 2 hours ago, saveasteading said: If it slings up high it is taking a longer route and slowing Swapping kinetic energy for potential energy, which will be used later. I suspect the biggest problem is friction/striction. I think I read somewhere that took great a fall can cause problems as the solids stick to the pipe because the fluids have passed by too quickly. Link to comment Share on other sites More sharing options...
saveasteading Posted February 10 Share Posted February 10 5 hours ago, SteamyTea said: potential energy, which will be used later. Friction and turbulence. The extreme would be a non moulded corner, and this is in-between. The same is happening in pressure pipes where sharp turns should be minimised. 5 hours ago, SteamyTea said: too great a fall can cause problems as the solids stick to the pipe because the fluids have passed by too quickly. That's correct. And using too big a pipe can do the same. The range of gradients in the building regulations is slightly conservative but I stick to them to allow for real life level control. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 10 Share Posted February 10 21 minutes ago, saveasteading said: Friction I wonder, if it is possible, to put a lubricant in the flushing water. As long as it is environmentally benign, it could reduce water usage. Those of us that live in wet areas really should be using captured rainwater, should not be hard to design a roof with a gutter halfway down it that runs into a loft tank. Today I would have had about 100 litres at least. I had to unblock the car park drain today. Every so often it get blocked and floods. You may never need to clean a toilet again, thanks to a new material that keeps the bowl free of any waste By Alex Wilkins 21 August 2023 A test of the miniature toilet using dyed honey Bin Su et al. A 3D-printed toilet is so slippery that almost nothing can stick to it, even after heavy use, meaning it could massively reduce the amount of water used for flushing. There are many kinds of slippery toilet surfaces, like Teflon-coated bowls, but they all suffer from a lack of durability. The more they are used, the less slippery they become, so the coating or toilet needs to be replaced for it to remain effective. Now, Yike Li at Huazhong University of Science and Technology in Wuhan, China, and his colleagues have developed a toilet that is extremely slippery and remains so in the face of abrasion. Li and his team made a model of the toilet, around 10 times smaller than a full-sized version, by 3D printing a mixture of plastic and hydrophobic sand grains, using a laser to fuse the particles together and create a complex structure. They then lubricated the surface with a kind of silicon oil, which also penetrated below the surface because of the toilet’s material structure. The researchers tested the toilet by throwing muddy water, milk, yogurt, honey, starch-filled gel and synthetic faeces into it, and found that none of them stuck. In fact, the toilet was just as slippery even after rubbing it with sandpaper more than 1000 times, which is a result of the lubricant oil sitting below the rubbed-away surface, says Li. 1 Link to comment Share on other sites More sharing options...
saveasteading Posted February 10 Share Posted February 10 42 minutes ago, SteamyTea said: result of the lubricant oil sitting below the rubbed-away surface, says Li. I don't understand that bit. There already are some super slippy wc pans, at a cost. But this is just to make the brush redundant, not aid drainage. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 11 Share Posted February 11 8 hours ago, saveasteading said: 9 hours ago, SteamyTea said: result of the lubricant oil sitting below the rubbed-away surface, says Li. I don't understand that bit. I think it is just highlighting the structure's properties. Link to comment Share on other sites More sharing options...
saveasteading Posted February 11 Share Posted February 11 3 hours ago, SteamyTea said: the structure's properties Porous with the pores filled with oil? Link to comment Share on other sites More sharing options...
SteamyTea Posted February 11 Share Posted February 11 26 minutes ago, saveasteading said: Porous with the pores filled with oil? I think so. It could be that the silicone oil molecule, that is attracted to the plastic or sand, while the other end repels water or carbon. Link to comment Share on other sites More sharing options...
FuerteStu Posted February 11 Share Posted February 11 13 hours ago, SteamyTea said: I wonder, if it is possible, to put a lubricant in the flushing water. I considered this after living in an old victorian house at the bottom of a gradual hill. Several times a year the manhole cover would lift off with all the wipes and debris. I asked a drain cleaning company if there was anything we could line the outgoing pipe with (where the common blockage would form). He pointed out the concrete and clay surfaces that had been eroded by all the chemicals and detergents flushed down there. It looked like the inside was lined with gravel. I think half the problems in the systems are the age and materials used Modern pvc won't have those issues. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 11 Share Posted February 11 (edited) 40 minutes ago, FuerteStu said: Modern pvc won't have those issues. It does degrade, just hopefully slower and in a more predictable way. Edited February 11 by SteamyTea Link to comment Share on other sites More sharing options...
ToughButterCup Posted February 13 Share Posted February 13 On 10/02/2024 at 19:49, SteamyTea said: ... You may never need to clean a toilet again, thanks to a new material that keeps the bowl free of any waste ... Wise use of the Conditional tense. '...may never...' Yeah, right. I'm thinking of marketing the output of our two grandchildren as StickToAnythingShit . "Grandad he's done it (his brother) again , come quick ! I'll get the coal shovel eh Grandad? Coal shovel? Why? Well thats what my daddy uses. Oh how children dob their parents in soooo easily. Link to comment Share on other sites More sharing options...
Mr Punter Posted February 13 Share Posted February 13 On 10/02/2024 at 13:53, SteamyTea said: I think I read somewhere that took great a fall can cause problems as the solids stick to the pipe because the fluids have passed by too quickly. I think this is no longer considered the case. Years ago there were maximum recommended gradients for drainage. They have now been abandoned as they had no basis in evidence. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 13 Share Posted February 13 35 minutes ago, Mr Punter said: They have now been abandoned as they had no basis in evidence Could be that PVC pipes are inherently smoother, including the joints. My first house had a glazed downpipe, had been repaired with some concrete mix. The Richards often got stuck halfway down. The next house and all but one since had PVC, no problems, except the old one in Weymouth. Link to comment Share on other sites More sharing options...
saveasteading Posted February 13 Share Posted February 13 5 hours ago, Mr Punter said: They have now been abandoned as they had no basis in evidence. I can give the evidence. I've seen it plenty of times. In an active system the next flush will probably move it all along though. But I think it is a real thing. I'd have to look at the reg's to see if it has been quietly dropped or simply isn't covered any longer. Link to comment Share on other sites More sharing options...
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