User Panel
User Panel
User Panel
|
Posted: 3/26/2017 5:32:25 PM EDT
[#1]
Quote HistoryQuoted:
Are they about to conclude this release through the spillway? They're at 839 feet on the lake. Also they said they'd only be running it for a few days... 4 I think. |
|
|
|
Posted: 3/26/2017 5:44:01 PM EDT
[#2]
Quote HistoryQuoted:
He didn't nail anything, and neither did you. The hydrostatic pressure is dependent upon the amount of drop relative to the entry point. The examples in that document only use a 30ft drop (likely because no one has ever bothered trying anything the size of this since there was never a need), but while the Oroville dam has a maximum height/depth of @ 900ft, the syphon's entry would only need to be about half of that, leaving a hydrostatic drop of @ 450ft relative to the exit point. If both entry & exit points are under water (so as not to introduce large amounts of air into the system, the rate of flow can be easily controlled by gate valves. ...Also, that document only mentions pressurized syphon systems, not natural vacuum syphon systems such as this. The maximum amount of flow would depend upon the number of pipes used, and sure - it wouldn't be all that cost effective relative to the amount of overall discharge produced, but still - I have never heard of a syphon system having a failure such to the extent that it could ever possibly cause damage to the structure of the dam. When these type of systems fail, they simply stop functioning. |
|
|
|
Posted: 3/26/2017 7:34:03 PM EDT
[#3]
Quote HistoryQuoted:
Disappointed dam didn't break flooding a good deal of commie CA. 
|
|
|
|
Posted: 3/26/2017 7:56:23 PM EDT
[#4]
Siphon would get interesting about the time something like a tree blocked the entrance for a moment.
I could just imagine the torrent of water coming out of that thing. It would be awesome - just before the turbulence destroyed it and washed out the face of the dam. |
|
|
|
Posted: 3/26/2017 8:07:13 PM EDT
[#5]
Quote HistoryQuoted:
Depends on what you make the pipe out of & how thick the pipe wall is, but even aside from that - why 5ft diameter for a single pipe? If you could do the same job with a thicker-walled 5 inch pipe using 500 of them or so to produce a similar overall flow-rate? I don't know what the answer would be, I only know that there is one. Like I said before - this kind of stuff gives me a headache.  Quote HistoryQuoted:
Quoted:
How about thinking about how much vacuum you would need to pull water up say 100 feet a 5 foot or bigger diameter pipe. Think about what that vacuum would do to that pipe. I have seen piping collapse that was not designed for vacuum. I have seen how thick piping designed for vacuum is for a very much smaller pipe and to imagine the scale of such a project I do not believe there is any pipe made like that. I don't know what the answer would be, I only know that there is one. Like I said before - this kind of stuff gives me a headache. |
|
|
|
Posted: 3/26/2017 8:12:59 PM EDT
[#6]
Quote HistoryQuoted:
He didn't nail anything, and neither did you. The hydrostatic pressure is dependent upon the amount of drop relative to the entry point. The examples in that document only use a 30ft drop (likely because no one has ever bothered trying anything the size of this since there was never a need), but while the Oroville dam has a maximum height/depth of @ 900ft, the syphon's entry would only need to be about half of that, leaving a hydrostatic drop of @ 450ft relative to the exit point. If both entry & exit points are under water (so as not to introduce large amounts of air into the system, the rate of flow can be easily controlled by gate valves. ...Also, that document only mentions pressurized syphon systems, not natural vacuum syphon systems such as this. The maximum amount of flow would depend upon the number of pipes used, and sure - it wouldn't be all that cost effective relative to the amount of overall discharge produced, but still - I have never heard of a syphon system having a failure such to the extent that it could ever possibly cause damage to the structure of the dam. When these type of systems fail, they simply stop functioning. Now go find out the physics that makes a syphon work, before you run out of toes on the other foot. As XD-Fan said, its all related to atmospheric pressure, which is 14.7 psi, on a standard day. |
|
|
|
Posted: 3/26/2017 8:25:52 PM EDT
[#7]
California operates some very large, very long siphons... it's not impossible, you just need valves in the right place.
|
|
|
|
Posted: 3/26/2017 9:23:45 PM EDT
[#8]
First I'll say I don't think you could build a siphon big enough to amount to much. Just let those turbines run full. Shut off the nuclear/coal/gas power plants instead. That said I don't think atmosphere pressure affects a siphon the way some here do. If the low fall exhaust side is significantly below the intake side it will pull the water. If you put a control valve on the intake and exhaust and closed them, then you could certainly add a tee at the top and pump the line full of water then close off the tee valve and open the intake and exhaust valves and it should run. You just have to be sure siphons with all these valves dont have air leaks. We ran an 8" siphon off a small levee once. They were using a flexible hose and they kept having trouble keeping the hose on the intake submerged properly and I don't think they ever completely got all the air evacuated properly it would run good a while then slow down and stop.
ETA a siphon is just simply gravity working. |
|
|
|
Posted: 3/26/2017 9:49:30 PM EDT
[#9]
If only I could go back to being an 8th grader...
|
|
|
|
Posted: 3/26/2017 10:11:46 PM EDT
[#10]
Quote HistoryQuoted:
How about thinking about how much vacuum you would need to pull water up say 100 feet a 5 foot or bigger diameter pipe. Think about what that vacuum would do to that pipe. I have seen piping collapse that was not designed for vacuum. I have seen how thick piping designed for vacuum is for a very much smaller pipe and to imagine the scale of such a project I do not believe there is any pipe made like that. Quote HistoryQuoted:
Quoted:
Why do you think so? foot or bigger diameter pipe. Think about what that vacuum would do to that pipe. I have seen piping collapse that was not designed for vacuum. I have seen how thick piping designed for vacuum is for a very much smaller pipe and to imagine the scale of such a project I do not believe there is any pipe made like that. |
|
|
|
Posted: 3/26/2017 10:21:56 PM EDT
[#11]
Quote HistoryQuoted:
Doesn't matter how strong the pipe is. You can't pull water more than 33.9ft. At that point no matter how hard the suction all you do is form a vacuum, the water won't go higher. |
|
|
|
Posted: 3/26/2017 10:28:28 PM EDT
[#12]
Wiki actually has a decent summary of how a siphon actually works. Scroll way down to the bottom of the article for a calculation of maximum height of a siphon.
siphons |
|
|
|
Posted: 3/26/2017 11:38:29 PM EDT
[#13]
Quote HistoryQuoted:
I call them turbulators. Quote HistoryQuoted:
Quoted:
Good eye.  Ping G30 Driver "Turbulators" (Music Video) |
|
|
|
Posted: 3/27/2017 12:43:36 AM EDT
[#14]
|
|
|
|
Posted: 3/27/2017 1:10:35 AM EDT
[#15]
As someone commented earlier in the thread, at 100,000 cfs that spillway has more cfs than the Mississippi river.
Seems that any siphon that could possibly be built, would be rather puny by any comparison. |
|
|
|
Posted: 3/27/2017 2:08:33 AM EDT
[#16]
Quote HistoryQuoted:
As someone commented earlier in the thread, at 100,000 cfs that spillway has more cfs than the Mississippi river. St Cloud, MN is around 9,000 cfs. But down in St Louis, the Mississippi is currently flowing 179,000 cfs... And when you get to Baton Rouge the flow is over 500,000 cfs. |
|
|
|
Posted: 3/27/2017 7:16:57 AM EDT
[#17]
Quote HistoryQuoted:
As XD-Fan said, its all related to atmospheric pressure, which is 14.7 psi, on a standard day. |
|
|
|
Posted: 3/27/2017 7:44:40 AM EDT
[#18]
Quote HistoryQuoted:
Well, I suppose at some points up north... St Cloud, MN is around 9,000 cfs. But down in St Louis, the Mississippi is currently flowing 179,000 cfs... And when you get to Baton Rouge the flow is over 500,000 cfs. Quote HistoryQuoted:
Quoted:
As someone commented earlier in the thread, at 100,000 cfs that spillway has more cfs than the Mississippi river. St Cloud, MN is around 9,000 cfs. But down in St Louis, the Mississippi is currently flowing 179,000 cfs... And when you get to Baton Rouge the flow is over 500,000 cfs. Link "The Flood of 2011 set new record stages at Vicksburg and Natchez.[26][27] The peak streamflow at Vicksburg, 2,310,000 cubic feet per second (65,000 m3/s), exceeded both the estimated peak streamflow of the Great Mississippi Flood of 1927, 2,278,000 cu ft/s (64,500 m3/s), and the measured peak streamflow of the 1937 flood, 2,080,000 cu ft/s " |
|
|
|
Posted: 3/27/2017 8:17:58 AM EDT
[#19]
Quote HistoryQuoted:
The lower Mississippi river has topped 2,000,000 cfs at times. Link "The Flood of 2011 set new record stages at Vicksburg and Natchez.[26][27] The peak streamflow at Vicksburg, 2,310,000 cubic feet per second (65,000 m3/s), exceeded both the estimated peak streamflow of the Great Mississippi Flood of 1927, 2,278,000 cu ft/s (64,500 m3/s), and the measured peak streamflow of the 1937 flood, 2,080,000 cu ft/s " Quote HistoryQuoted:
Quoted:
Quoted:
As someone commented earlier in the thread, at 100,000 cfs that spillway has more cfs than the Mississippi river. St Cloud, MN is around 9,000 cfs. But down in St Louis, the Mississippi is currently flowing 179,000 cfs... And when you get to Baton Rouge the flow is over 500,000 cfs. Link "The Flood of 2011 set new record stages at Vicksburg and Natchez.[26][27] The peak streamflow at Vicksburg, 2,310,000 cubic feet per second (65,000 m3/s), exceeded both the estimated peak streamflow of the Great Mississippi Flood of 1927, 2,278,000 cu ft/s (64,500 m3/s), and the measured peak streamflow of the 1937 flood, 2,080,000 cu ft/s " |
|
|
|
Posted: 3/27/2017 8:38:28 AM EDT
[#20]
Quote HistoryQuoted:
450 feet of water is about 13.5 atmospheres of pressure. How do you prime a system like that? |
|
|
|
Posted: 3/27/2017 11:12:24 AM EDT
[#21]
Quote HistoryQuoted:
Plug both ends, pump full of water, open both ends. |
|
|
|
Posted: 3/27/2017 11:31:19 AM EDT
[#22]
Quote HistoryQuoted:
Now you have a pipe full of water that won't flow. What good is that?z TA DA! Of course it would probably collapse and rupture at the high point and just drain the pipe so it wouldn't likely wash out the dam or anything. |
|
|
|
Posted: 3/27/2017 11:54:15 AM EDT
[#23]
Quote HistoryQuoted:
Doesn't matter how strong the pipe is. You can't pull water more than 33.9ft. At that point no matter how hard the suction all you do is form a vacuum, the water won't go higher. |
|
|
|
Posted: 3/27/2017 12:48:52 PM EDT
[#24]
Quote HistoryQuoted:
It sounds as if nobody here ever heard of a water barometer. Quote HistoryQuoted:
Quoted:
Doesn't matter how strong the pipe is. You can't pull water more than 33.9ft. At that point no matter how hard the suction all you do is form a vacuum, the water won't go higher. Although siphons can exceed the barometric height of the liquid in special circumstances, e.g. when the liquid is degassed and the tube is clean and smooth,[84] in general the practical maximum height can be found as follows. Setting equations 1 and 3 equal to each other gives: {\displaystyle {0^{2} \over 2}+g(0)+{P_{\mathrm {atm} } \over \rho }={v_{B}^{2} \over 2}+gh_{B}+{P_{B} \over \rho }} {0^2 \over 2}+g(0)+{P_\mathrm{atm} \over \rho}={v_B^2 \over 2}+gh_B+{P_B \over \rho} Maximum height of the intermediate high point occurs when it is so high that the pressure at the intermediate high point is zero; in typical scenarios this will cause the liquid to form bubbles and if the bubbles enlarge to fill the pipe then the siphon will "break". Setting PB = 0: {\displaystyle {P_{\mathrm {atm} } \over {\rho }}={v_{B}^{2} \over 2}+gh_{B}} {P_\mathrm{atm} \over {\rho}}={v_B^2 \over 2}+gh_B Solving for hB: General height of siphon: {\displaystyle h_{B}={P_{\mathrm {atm} } \over \rho g}-{v_{B}^{2} \over 2g}.} h_B={P_\mathrm{atm} \over \rho g} - {v_B^2 \over 2g}. This means that the height of the intermediate high point is limited by pressure along the streamline being always greater than zero. Maximum height of siphon: {\displaystyle h_{B\mathrm {,max} }={P_{\mathrm {atm} } \over \rho g}} h_{B\mathrm{,max}}={P_\mathrm{atm} \over \rho g} This is the maximum height that a siphon will work. Substituting values will give approximately 10 metres for water and, by definition of standard pressure, 0.76 metres (760 mm or 30 in) for mercury. The ratio of heights (about 13.6) equals the ratio of densities of water and mercury (at a given temperature). Note that as long as this condition is satisfied (pressure greater than zero), the flow at the output of the siphon is still only governed by the height difference between the source surface and the outlet. Volume of fluid in the apparatus is not relevant as long as the pressure head remains above zero in every section. Because pressure drops when velocity is increased, a static siphon (or manometer) can have a slightly higher height than a flowing siphon. |
|
|
|
Posted: 3/27/2017 12:50:10 PM EDT
[#25]
This thread has taken me places. For a long time I thought "what dumbasses, they should have kept the diversion tunnels.!"
Among other reasons stated, that would be impossible. Impossible because if a valve fails, how to you fix it? Only way would be to drain the lake to river level. Not feasible. They didn't plug the tunnels because they wanted to, they plugged them because they had to. |
|
|
|
Posted: 3/27/2017 1:27:57 PM EDT
[#26]
Today's 11am pst press conference will unfortunately be here: https://www.facebook.com/CADWR/
If anyone finds a youtube or periscope link please post it. |
|
|
|
Posted: 3/27/2017 2:09:35 PM EDT
[#27]
Quote HistoryQuoted:
Today's 11am pst press conference will unfortunately be here: https://www.facebook.com/CADWR/ If anyone finds a youtube or periscope link please post it.  Lake Oroville Spillway Press Briefing | 3-27-2017 |
|
|
|
Posted: 3/27/2017 2:29:31 PM EDT
[#28]
Quote HistoryQuoted:
 https://www.youtube.com/watch?v=MjiAdNcjI6c" target="_blank">https://www.youtube.com/watch?v=MjiAdNcjI6cStarting to shutdown main spillway at noon. 6 hours to full shutdown. Power plant is currently not flowing but will start flowing again as the main spillway is shut down. The main concern is the height of the water in the pool beneath the dam and the back pressure that can place on the turbines. Expecting to start back up around 4pm. They'll inspect and repair what they can during the time they have while the main spillway is shut down. Work will be done to prevent further erosion of the slopes around the spillway. They have a rock crusher on site now. Concrete batch plant is being procured. They hope to have a spillway to use by Nov 1... it might be temporary... Expect to use the spillway at least 1 more time... and maybe 2-3 more times. Will wait until water gets back up to 860 or 865 to use it again. |
|
|
|
Posted: 3/27/2017 3:25:57 PM EDT
[#29]
Quote HistoryQuoted:
How about thinking about how much vacuum you would need to pull water up say 100 feet a 5 foot or bigger diameter pipe. Think about what that vacuum would do to that pipe. I have seen piping collapse that was not designed for vacuum. I have seen how thick piping designed for vacuum is for a very much smaller pipe and to imagine the scale of such a project I do not believe there is any pipe made like that. There are many ways to prime a siphon... 
|
|
|
|
Posted: 3/27/2017 3:31:34 PM EDT
[#30]
Seems someone earlier in the thread was wrong.
Teach me to quote an unsubstantiated source. 
|
|
|
|
Posted: 3/27/2017 3:45:06 PM EDT
[#31]
Quote HistoryQuoted:
You can only pull it up about 30 feet no mater what. You are relying on atmospheric pressure to provide the 'driving' force. 14.7 PSI. Laminar flow is less damaging but very difficult to maintain as velocity climbs on a large drop. The viscosity of water is the viscosity of water and that drives a whole lot of flow calculations. I have not done any of this kind of work in 30 years. We had to deal with Reynolds numbers and boundary flow conditions. You can destroy all sorts of equipment when flow gets turbulent inside a line. Precisely! If even that and at sea level... There IIRC, the height of a column of water whose weight is equal to ~14.7 psi is ~32 feet... Now, this all may be reversed in the Southern Hemisphere... |
|
|
|
Posted: 3/27/2017 4:31:54 PM EDT
[#32]
Quote HistoryQuoted:
There IIRC, the height of a column of water whose weight is equal to ~14.7 psi is ~32 feet... |
|
|
|
Posted: 3/27/2017 4:57:40 PM EDT
[#33]
Quote HistoryQuoted:
Pressure.
|
|
|
|
Posted: 3/27/2017 8:15:12 PM EDT
[#34]
Ahahahahaha..............lololol..................errrr...............ummmmm...........(facepalm).
I have finally seen the light - or rather ....been smacked by it, and now see the error of my prior beliefs. My apologies to those of Arfcom whom I may have offended in my ignorance. ...I did mention this stuff makes my head hurt, right?
|
|
|
|
Posted: 3/27/2017 10:26:41 PM EDT
[#35]
Quote HistoryQuoted:
Ahahahahaha..............lololol..................errrr...............ummmmm...........(facepalm). I have finally seen the light - or rather ....been smacked by it, and now see the error of my prior beliefs. My apologies to those of Arfcom whom I may have offended in my ignorance. ...I did mention this stuff makes my head hurt, right? 
|
|
|
|
Posted: 3/27/2017 10:43:49 PM EDT
[#36]
Here's a picture of the gate damage at Folsom. Amazing what a little water can do.
|
|
|
|
Posted: 3/27/2017 11:34:10 PM EDT
[#37]
math sucks. barometric water vacuum siphon math really sucks
. 
|
|
|
|
Posted: 3/28/2017 6:27:21 AM EDT
[#38]
Quote HistoryQuoted:
very likely yeah. They're at 839 feet on the lake. Also they said they'd only be running it for a few days... 4 I think. They have 11-12k CFS going through the turbines. |
|
|
|
Posted: 3/28/2017 7:20:40 AM EDT
[#39]
Quote HistoryQuoted:
math sucks. barometric water vacuum siphon math really sucks . http://www.njrod.com/images/hf/3rdgrademath.jpg   
|
|
|
|
Posted: 3/28/2017 7:51:54 AM EDT
[#40]
Maybe we'll have some new pics of the spillway today.
Curious to see how the temporary repairs\patches held up. |
|
|
|
Posted: 3/28/2017 10:52:45 AM EDT
[#41]
https://i.redd.it/m82ph5vzh4oy.jpg It's a hi- res pic. Rt click and zoom in. its pretty neat. 
Video from Channel 3 helo. https://www.facebook.com/KCRA3/videos/10155164766681514/ More info here. https://orovilledam.org/ |
|
|
|
Posted: 3/28/2017 11:11:24 AM EDT
[#42]
Looks like their half-assed shotcrete patching held up O.K. and they were able to get the Hyatt powerplant spun right up.
|
|
|
|
Posted: 3/28/2017 11:13:09 AM EDT
[#43]
 Oroville 27 March Update "A Day in the Life" |
|
|
|
Posted: 3/28/2017 11:44:36 AM EDT
[#44]
|
|
|
|
Posted: 3/28/2017 12:57:22 PM EDT
[#45]
 Oroville Spillway March 27, 2017 |
|
|
|
Posted: 3/28/2017 1:30:07 PM EDT
[#46]
Quote HistoryQuoted:
https://www.youtube.com/watch?v=ixTg5Tgzeus" target="_blank">https://www.youtube.com/watch?v=ixTg5Tgzeus |
|
|
|
Posted: 3/28/2017 2:42:04 PM EDT
[#47]
Quote HistoryQuoted:
Last little bit of that video... Definitely moved a fair bit of the remaining debris back out into the channel. They'll have to be back at the dredging work for a while. Quote HistoryQuoted:
Quoted:
https://www.youtube.com/watch?v=ixTg5Tgzeus" target="_blank">https://www.youtube.com/watch?v=ixTg5TgzeusLooks like they went plenty deep on the opposite side channel, though,. |
|
|
|
Posted: 3/28/2017 3:08:00 PM EDT
[#48]
Quote HistoryQuoted:
Probably would flow - the vacuum created would collapse the pipe, somewhere along the line something would rupture, and you'd have flow. TA DA! Of course it would probably collapse and rupture at the high point and just drain the pipe so it wouldn't likely wash out the dam or anything. |
|
|
|
Posted: 3/28/2017 3:41:18 PM EDT
[#49]
Quote HistoryQuoted:
Probably would flow - the vacuum created would collapse the pipe, somewhere along the line something would rupture, and you'd have flow. TA DA! Of course it would probably collapse and rupture at the high point and just drain the pipe so it wouldn't likely wash out the dam or anything. Quote HistoryQuoted:
Quoted:
Now you have a pipe full of water that won't flow. What good is that?z TA DA! Of course it would probably collapse and rupture at the high point and just drain the pipe so it wouldn't likely wash out the dam or anything. |
|
|
|
Posted: 3/28/2017 9:39:51 PM EDT
[#50]
What happened to ProFryan? Is he still around?
|
|
|
Win a FREE Membership!
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.
