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Old 04/03/2012, 06:49 AM   #1
sefrayser
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Durso Drain Help?

I made a Durso for my 90 gallon corner. It has a 1" bulkhead and I made the Durso out of 1 1/4" pipe with a reducer at the bulkhead. I have a Mag 9.5 pushing water with aprox 5' of head. I have the pump gated back with a gate valve and it is about 1/4 closed. I started with 9/64 hole and have worked my up to 1/4 hole. The water level is constant but I still have the gurgling sound. I have the discharge pipes about 1-2" under the water in the sump. I also have them on gate valves and have them gated back a little. I tried putting a piece of air line tubing in the hole and the level started to raise and lower. I put a valve on the air tubing and it did the same thing. What can I do to quite it down a little? I have the "L" that comes off the standpipe about 2" under the water or 2" under the overflow fingers. By making the hole bigger water does that do?


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Old 04/03/2012, 07:08 AM   #2
der_wille_zur_macht
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A few questions.

Quote:
Originally Posted by sefrayser View Post
I have the discharge pipes
Plural? Do you have one drain or two? Can you describe the drain plumbing all the way from the standpipe(s) to the opening in the sump, or show a photo?

Quote:
I have the discharge pipes about 1-2" under the water in the sump. I also have them on gate valves and have them gated back a little.
If you're referring to putting gate valves on your drain plumbing, you should never do that (unless it's on a system designed to operate with a valve, i.e. a Herbie or beananimal system).

Quote:
I tried putting a piece of air line tubing in the hole and the level started to raise and lower. I put a valve on the air tubing and it did the same thing. What can I do to quite it down a little? I have the "L" that comes off the standpipe about 2" under the water or 2" under the overflow fingers. By making the hole bigger water does that do?
Changing the hole size on a Durso alters how much air gets sucked into the pipe. When a Durso is operating correctly, it acts as a mixed drain - both water and air go down the pipe. This is the "magic" that lets it self-adjust to small changes in the system, vs. a full siphon which (on it's own) is less forgiving. The gurgling noise is essentially the sound of the air and water mixing as they flow down the pipe. Some people will tell you that you can never get rid of this noise with a Durso unless you have insanely low flow rates, but IME after ~15 years of using them there are a few tricks you can try.

First, you need an understanding of how to read the drain's performance. If the water level is rapidly fluctuating up and down every few seconds, you've essentially formed a siphon (when it gets low, it breaks, which lets the level rise back up). Essentially this means you need less water in the pipe, and/or more air. You can get less water by valving back your return pump, or more air by enlarging the hole.

Speaking of the hole, I'd suggest to drill out to a larger hole size than you think you need and put hose (airline or slightly larger vinyl hose) into the hole. Leave it longer than you think you need and put a valve on the free end so you can tweak the air flow rate - this lets you control how much air goes down without having to re-drill the hole every time you want to change the rate.

Once you're at a point where you are happy with the flow rate (i.e. the return pump's rate) and it is not siphoning, you can fiddle to try to get it less noisy. There are a few things to try, but it's not always straightforward, so you pretty much just have to play. Suggestions:

1) Push the airline deeper down into the drain. This moves the point of air entry deeper into the drain, which can muffle the noise.

2) Raise the plumbing in the sump higher or lower - this puts less or more backpressure on the drain, which alters whether or not the air actually mixes with the water, vs. forming a more stable laminar flow into the sump.

3) Close the valve on the airline to reduce the amount of air entering the pipe. If you start getting siphoning again, you've closed it too much.

4) As a last resort, valve your return pump back and try again at a lower flow rate.

5) As a last last last resort, tear down the system and rebuild it with a Herbie or Beananimal drain. These are, in nearly every way, vastly superior to Durso drains.


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Old 04/03/2012, 07:22 AM   #3
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I have one discharge pipe from the tank and then I put a "T" in it to feed the skimmer section and fuge section in my sump. My sump is a 30 gallon and I have it set-up: 1st chamber: skimmer, 2nd chamber: return, 3rd chamber, fuge. I will take a look at you options and see if one will work.
The herbie drain needs 2 or 3 outputs? I only have one so I guess the herbie is out?


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Old 04/03/2012, 07:56 AM   #4
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Herbie needs two, beananimal needs three. If you have a typical "megaflow" AGA tank (or an imitator) and you have a hole in your overflow meant for a return pipe, you could steal that and send the return over the back/side wall of the tank.

I'd think about redesigning your drain system such that there is only a single path for the water to your sump. Introducing T's and branches on a Durso can make it very frustrating (though not impossible) to keep stable and quiet. If you want to feed the refugium separately, you could T off the return plumbing. That would reduce the flow rate through the overflow which would also contribute to getting it more quiet.


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Old 04/03/2012, 01:34 PM   #5
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remove the t from your drain. you can send water to your fuge by using a t on your return. i think the gurgling sound is a result of the air hole you have drilled in the top of your durso drain, i think it needs to be bigger. however i wouldn't mess with this until you remover the the t on your drain, you want more of a straight route to the sump.

http://www.dursostandpipes.com/


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Old 04/03/2012, 04:43 PM   #6
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Quote:
Originally Posted by sefrayser View Post
I made a Durso for my 90 gallon corner. It has a 1" bulkhead and I made the Durso out of 1 1/4" pipe with a reducer at the bulkhead. I have a Mag 9.5 pushing water with aprox 5' of head. I have the pump gated back with a gate valve and it is about 1/4 closed. I started with 9/64 hole and have worked my up to 1/4 hole. The water level is constant but I still have the gurgling sound. I have the discharge pipes about 1-2" under the water in the sump. I also have them on gate valves and have them gated back a little. I tried putting a piece of air line tubing in the hole and the level started to raise and lower. I put a valve on the air tubing and it did the same thing. What can I do to quite it down a little? I have the "L" that comes off the standpipe about 2" under the water or 2" under the overflow fingers. By making the hole bigger water does that do?
The noise is due to the flow rate to the tank, the 1" bulkhead, the valves in the drain line, the tee in the drain line, and the fact that it is a durso standpipe.

The flow rate for durso standpipes, is low--this is inherent to the design. When the flow rate becomes to high, the pipe becomes too full of water (over 1/4 full,) and water no longer flows on the wall of the pipe, with calm air in the middle, as it should for silence and reliability. The "laminar" flow rate is rather low, probably below 350 gph for the 1.25" pipe, and the 1" pipe below the bulkhead, though you did not state the pipe size.

There should not ever be a valve in a drain line, unless you have a dry emergency back up, especially with a durso--as it causes turbulence (air and water mixing) and presents a plug hazard. Flow rate is never controlled by a valve on the drainline, rather a valve on the pump return. Durso or any drain lines should not be split to feed two different sections of your sump, as this causes issues with open channel drains (dursos) and may cause issues with siphons as well. Never restrict, with a valve, any drain line unless it is a siphon, with a dry emergency.

Durso standpipes, are never quite quiet, never quite reliable, never quite stable. They are designed for low flow systems, where the flow rate is such that these problems do not occur.

Reconfigure your drain without the valves, tees, splits, elbows, and run it as straight down as possible, use 45°'s if needed, but 90°'s will cause turbulence (noise). Don't add gimmicks as they don't work without an associated reduction in flow rate, and in fact without the gimmicks, reducing the flow rate is part of the cure, often the whole cure. The hole size, is never the same between any two systems, and is an unreliable tuning tool. Lowering the flow rate and increasing the pipe size cures the problem. Or convert your drain system to a siphon system. Siphon systems are silent and problem free ("Herbie" can and does show some instability at times)


Mag 9.5, you are using 1.5" return pipe as per the instructions yes?


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Old 04/03/2012, 10:00 PM   #7
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Mag 9.5 yes.


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Old 04/04/2012, 06:09 AM   #8
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Originally Posted by uncleof6 View Post
................Durso standpipes, are never quite quiet, never quite reliable, never quite stable. They are designed for low flow systems, where the flow rate is such that these problems do not occur.
Wow, overall I don't think you could be more wrong if you tried.

As quiet as a full siphon? No, but a durso can be relatively quiet.

Reliable? As reliable as it gets. That's the beauty of not running a full siphon - it can flow far more than when it's running correctly (i.e. it will siphon -> break -> siphon). Unless there's huge obstruction in the line it will not fail. They have been in use for far longer than either of the full siphon methods..............number of fails other than a clog? Never heard of one.

A 1" durso will flow about 600gph, not 350 for 1.25". Far less than a full siphon but far more than you state.

OP - the best way to get a Durso quiet is to drill holes in the cap/top of the pipe - the part above the T. Drill 4 holes through both the cap & the pipe. Now you can turn the cap to adjust the airflow. Turn down the airflow until you get the siphon/flush -> open it up a tad, it will be as quiet as it will get. When you hear the air sucking sound you have it too far open.


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Old 04/04/2012, 07:24 AM   #9
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Well I have it pretty quite right now. It doesnt appear to be "flushing". I put a piece of air tubing it it. I think when I get the canopy on it will be ok.


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Old 04/04/2012, 10:07 AM   #10
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Do you have a maxi jet? If you do, it came with a airline tube and a air adjustment. You can use this on your durso to adjust air flow.


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Old 04/04/2012, 10:32 AM   #11
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Actually that is the tubing I used. I just didnt use the air adjuster. I put it on and even at wide open it didnt act right so I just left it off.


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Old 04/04/2012, 01:45 PM   #12
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Wow, overall I don't think you could be more wrong if you tried.

The volume of simple evidence and the numbers of problems associated with durso standpipes says, that I-- and many others that say the same thing--are absolutely correct.

As quiet as a full siphon? No, but a durso can be relatively quiet.

Reliable? As reliable as it gets. That's the beauty of not running a full siphon - it can flow far more than when it's running correctly (i.e. it will siphon -> break -> siphon). Unless there's huge obstruction in the line it will not fail. They have been in use for far longer than either of the full siphon methods..............number of fails other than a clog? Never heard of one.

This is an inaccurate statement, longer than the use of siphons has been reported on Reef Central, or other internet venues, perhaps. But this does not suggest that siphons have not been used far longer than the internet itself has existed. I am sorry, but this hobby does not begin or end with the internet.

Under conditions of laminar flow, open channels can be silent and absolutely reliable. I use many of them, running bean's system. Put very simply, you cannot beat the physics (the fluid dynamics) involved with open channel standpipes.

A 1" durso will flow about 600gph, not 350 for 1.25". Far less than a full siphon but far more than you state.

I would contend that it will not do so without some problems occurring. The physics say so. Once the pipe is 1/4 full of water, or more, the air and water mix, causing turbulent flow, the more filled the pipe (the higher the flow rate,) the larger the problems become, to the point of air locking, and flushing. Unfortunately, you cannot beat the physics.

As far as a 1" durso flowing 600 gph, even Richard Durso, the "inventor" of the durso, says that a 1" durso is for extremely low flow systems, and is impractical. The smallest practical durso is 1.25" on a 1" bulkhead. This is directly from the inventor.


OP - the best way to get a Durso quiet is to drill holes in the cap/top of the pipe - the part above the T. Drill 4 holes through both the cap & the pipe. Now you can turn the cap to adjust the airflow. Turn down the airflow until you get the siphon/flush -> open it up a tad, it will be as quiet as it will get. When you hear the air sucking sound you have it too far open.
Laminar flow is water flowing on the walls of the pipe, with calm air in the middle. The water is moving, the air is not. This is the principle by which durso stand pipes work. This is from fluid dynamics. The flow rates at which this occurs, are far below the "published" flow rates for a given pipe size. The "Siphon > break > siphon" is part of the problem, not: "running correctly."

To quote BeanAnimal:

"Standpipe Basics

A standpipe can only run silently under two conditions. 1) The volume of flow is low enough to allow the water to cascade down the walls of the standpipe, leaving an undisturbed column of air in the middle. When water falls vertically down a pipe, the water will adhere to the pipe's walls until the pipe's cross sectional area is about 1/4 full. At any higher volume the flow starts to become turbulent and traps air. The trapped air creates slurping and gurgling noises. 2) The volume of the flow is high enough to keep the pipe entrance submerged, creating a full siphon.


So to revisit, the Durso and Stockman mods are simply ways of trying to control the amount of air introduced into the standpipe, creating a balance somewhere between turbulent flow and a full siphon. This makes the setup very unstable and requires constant adjustment, not to mention that the setup is never truly silent or safe!"




The solution to the Durso, Stockman, and modifications of the same--is larger pipe, and lower flow rate.

As aquarists, there are three options: deal with the problems asscociated with open channel standpipes, accepting or tolerating "as good as it gets," OR, by understanding the fluid dynamics, making the adjustments and/or modifications that solve the issue, rather than "as good as it gets."

The third option is to run a siphon system.



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Last edited by uncleof6; 04/04/2012 at 01:54 PM.
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Old 04/04/2012, 02:41 PM   #13
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Wow, overall I don't think you could be more wrong if you tried.

As quiet as a full siphon? No, but a durso can be relatively quiet.

Reliable? As reliable as it gets. That's the beauty of not running a full siphon - it can flow far more than when it's running correctly (i.e. it will siphon -> break -> siphon). Unless there's huge obstruction in the line it will not fail. They have been in use for far longer than either of the full siphon methods..............number of fails other than a clog? Never heard of one.

A 1" durso will flow about 600gph, not 350 for 1.25". Far less than a full siphon but far more than you state.

OP - the best way to get a Durso quiet is to drill holes in the cap/top of the pipe - the part above the T. Drill 4 holes through both the cap & the pipe. Now you can turn the cap to adjust the airflow. Turn down the airflow until you get the siphon/flush -> open it up a tad, it will be as quiet as it will get. When you hear the air sucking sound you have it too far open.
This is great advice and what I do on my durso, using several holes and turning the cap/plug until you get the perfect mixture. I'm running about 550gph thru my 1" durso and you can't hear it even if you stick your head in my sump. The #1 thing people say when they come over to check out my tank is how quiet it is. I have never had a single problem in over 9 years using a durso.


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Old 04/05/2012, 06:09 AM   #14
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Originally Posted by uncleof6 View Post
............So to revisit, the Durso and Stockman mods are simply ways of trying to control the amount of air introduced into the standpipe, creating a balance somewhere between turbulent flow and a full siphon. This makes the setup very unstable and requires constant adjustment, not to mention that the setup is never truly silent or safe!"..............
And I can link to unreferenced Wiki pages, so what? About as valid as "I saw bigfoot" or "I saw a UFO". But carry on, I enjoy verbal "loose stools". I have no real interest in information from those who's only real claim to fame is the dogged determination to continue pontificating until the other party has given up.

Utter rubbish. It may not be 100% silent but it's certainly proven to be reliable. It may not be a high flow application but that's what we deal with for the most part - low flow applications. A full siphon on a 1" drain is what? Something like 2000 gph? And how many are using amount of flow? Not many I'd wager..........hence the common use of a valve to maintain the siphon..........which leads to -

Constant adjustment? That's rubbish, if anything needs constant adjustment it's a full siphon system. The flow changes & the siphon needs adjustment to maintain the desired functionality. This occurs frequently. Clean the pump = more flow & needs adjustment. Pump gets dirty = less flow & needs adjustment. What happens in the former case? Oh damn, that's right water level rises until it hits.....wait for it....the air beind water secondary drain which is noisy. In the later case the drain loses siphon and becomes....oh damn....an air behind water drain.

An air behind water drain can run anywhere from little to a full siphon without any adjustment......the only repercussion being noise.

The single issue is having a single drain & while redundancy is always better there are occasions where it's just not feasable.


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Old 04/05/2012, 02:12 PM   #15
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I have a Mag 9.5 as well, but a durso on a 1.5" drain with 1.5" PVC.

My top cap has two holes, roughly 3/16" dia each. My suggestion would be to drill a second hole, start at 1/8" and go from there. Mine is not silent but is quiet enough for me.

My drain pipe is submerged in the sump, but is still louder than the Durso. The loudest component of my system are the drain pipe and fans on my ATI sunpower. The durso is 3rd in line, tied with the Mag 9.5.


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Old 04/05/2012, 03:26 PM   #16
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Quote:
Originally Posted by ErikS View Post
And I can link to unreferenced Wiki pages, so what? About as valid as "I saw bigfoot" or "I saw a UFO". But carry on, I enjoy verbal "loose stools". I have no real interest in information from those who's only real claim to fame is the dogged determination to continue pontificating until the other party has given up.

Interesting, but that is not from an unreferenced wiki page. In fact here is the link:

http://www.beananimal.com/projects/s...ow-system.aspx

Utter rubbish. It may not be 100% silent but it's certainly proven to be reliable. It may not be a high flow application but that's what we deal with for the most part - low flow applications. A full siphon on a 1" drain is what? Something like 2000 gph? And how many are using amount of flow? Not many I'd wager..........hence the common use of a valve to maintain the siphon..........which leads to -

Constant adjustment? That's rubbish, if anything needs constant adjustment it's a full siphon system. The flow changes & the siphon needs adjustment to maintain the desired functionality. This occurs frequently. Clean the pump = more flow & needs adjustment. Pump gets dirty = less flow & needs adjustment. What happens in the former case? Oh damn, that's right water level rises until it hits.....wait for it....the air beind water secondary drain which is noisy. In the later case the drain loses siphon and becomes....oh damn....an air behind water drain.

An air behind water drain can run anywhere from little to a full siphon without any adjustment......the only repercussion being noise.

The single issue is having a single drain & while redundancy is always better there are occasions where it's just not feasable.
They physics (the actual science called Fluid Dynamics) say different.

Your post is inflammatory, however, it seems you want to take this topic into a debate, exactly on which topic you wish to debate, whether it be high vs low flow rate, or what is required to run a Durso Standpipe drain system silently and reliably, what the differences are between a siphon, and an open channel standpipe, or what the fluid dynamics say, I am uncertain. I don't mind at all if you disagree with me, however, it is hard to disagree with the physics. It is also rather difficult to argue with the person that invented the Durso Standpipe, and his statements concerning 1" standpipes.

The op wanted to know how to quiet the drain. You work with the physics, the problem is solved. You work against the physics, there will be some issues, demonstrated amply by the volume of threads concerning issues with durso standpipes, here on Reef Central.


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Old 04/05/2012, 03:40 PM   #17
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Quote:
Originally Posted by bongarone View Post
I have a Mag 9.5 as well, but a durso on a 1.5" drain with 1.5" PVC.

My top cap has two holes, roughly 3/16" dia each. My suggestion would be to drill a second hole, start at 1/8" and go from there. Mine is not silent but is quiet enough for me.

My drain pipe is submerged in the sump, but is still louder than the Durso. The loudest component of my system are the drain pipe and fans on my ATI sunpower. The durso is 3rd in line, tied with the Mag 9.5.
All part of the same issue. The flow rate is too high for the pipe size, to allow laminar flow. The noise you hear is due to turbulence. Removing restrictions, (valves, 90's etc,) increasing the pipe size, (a bit impractical as you are already at 1.5") and/or reducing the flow rate will silence the drain system.


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Old 04/05/2012, 09:50 PM   #18
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Not trying to start a debate.....just trying to fix my problem.


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Old 04/06/2012, 04:28 AM   #19
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Quote:
It is also rather difficult to argue with the person that invented the Durso Standpipe, and his statements concerning 1" standpipes.
If you going to quote someone you should at least do it correctly, and link to the information.

1 inch - 600 Gallons per hour per bulkhead.

http://dursostandpipes.com/faq/41-wh...urso-standpipe


I have run Durso's for over 12 years, my current tank and durso has been running for 10+ years, other than the few days to tune the durso it has been sealed in my overflow box and not adjusted in all that time, including when I have changed pumps. Nor have I had or heard of anyone ever having a failure with a durso.

No system is perfect but all have a role in a given situation, I have one overflow pipe, a Durso is the only logical option for me


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Old 04/06/2012, 09:14 AM   #20
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Keep it civil, please. These are drains, for gosh sake, not a constitutional amendment.
The sound can be a bit much: I solved my noise problem via brogan mechanics, simply by raising the water level in the overflow to reduce the drop. Marbles.


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Old 04/06/2012, 12:47 PM   #21
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If you going to quote someone you should at least do it correctly, and link to the information.

1 inch - 600 Gallons per hour per bulkhead.

http://dursostandpipes.com/faq/41-wh...urso-standpipe


I have run Durso's for over 12 years, my current tank and durso has been running for 10+ years, other than the few days to tune the durso it has been sealed in my overflow box and not adjusted in all that time, including when I have changed pumps. Nor have I had or heard of anyone ever having a failure with a durso.

No system is perfect but all have a role in a given situation, I have one overflow pipe, a Durso is the only logical option for me

Agreed, however the issue at hand, does not hinge on the flow capacity of a given bulkhead size, nor a given pipe size--rather the fluid dynamics of open channel drain systems. I did not "quote" Richard Durso, however, I will provide a quote, and the link to it.


"To Oversize or Not to Oversize

With 1 inch and smaller bulkheads the standpipe's PVC diameter needs to be larger than the bulkhead to work correctly. I get a lot of e-mail questions on why this is. Honestly, I’m not sure. Typically if you use 1 inch PVC pipe on a 1 inch bulkhead you get poor results. (Some exceptions with smaller low flow tanks.) Take my word on it and use 1 inch PVC pipe. For large tanks with 1.5 inch bulkheads and large return pumps however, there does not seem to be any need to oversize the standpipe for larger bulkheads. Bulkheads 1.5 inches and larger can use PVC pipe & fittings that match the size of the bulkhead. (I consider tanks in the 350 gallon and up good candidates for 1.5 inch bulkheads)."


http://www.dursostandpipes.com/make-your-own-diy

Fluid dynamics tells us why you will get poor results, and provides a guide to the limitations of the Durso, and similarly modified standpips, in larger sizes.

Yes a 1" bulkhead can flow 600 gph, it can actually flow 1500 or better, depending on the head height and the length of the drop. (simplified) Can a 1" durso standpipe/drain system do that--without issues (noise, gurgling, flushing, what have you)? No it cannot.


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Last edited by uncleof6; 04/06/2012 at 12:55 PM.
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Old 04/06/2012, 02:02 PM   #22
suphew
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I think you need to read what Richard says a bit more carefully, in the link you posted he states that a 1" bulkhead work poorly with a 1" standpipe, not that they work poorly as you stated. Also when he talks about 350g and bulkhead size he is talking about tank size not 350gph flow rates as you also stated.

Quote:
Yes a 1" bulkhead can flow 600 gph, it can actually flow 1500 or better, depending on the head height and the length of the drop. (simplified) Can a 1" durso standpipe/drain system do that--without issues (noise, gurgling, flushing, what have you)? No it cannot.
As per the link I provided and from personal experience a 1" can handle 600gph with no issues


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Old 04/06/2012, 02:49 PM   #23
BeanAnimal
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The point to walk away with here is that we can't cheat physics. As reality would have it, we often stumble upon something that works, even if we don't understand the physics. We often then assume that we can apply what we think we understand to other situations. Things don't always work out. The "air assisted" standpipes are a prime example in our hobby

When we talk about "durso", "stockman", "hoffer" or any other "air assisted" standpipe setup, we are talking about a system that is subject to numerous variables that affect its operation. What is quiet at a given flow rate in one environment may not be in another. There are simply too many variables that contribute to the operating mode of the system and subtle differences in standpipes can create rather dramatic differences in operation from one setup to the next.

These (and other) problems are much of the reason that I (and others) have designed standpipe systems that are predictable from one environment to the next.

Water flows through a standpipe due to the effect of gravity. The rate of flow of the system is function of the pipe volume and the resistance to flow created by the pipe configuration.

When we introduce air into the system, the air displaces what would otherwise be water. As the air to water ratio rises, the water begins to tumble and/or churn because the air does not fall as fast as the water around it. The net effect is very dependent on MANY factors (length of pipe, diameter of pipe, back pressure on pipe, roughness of pipe, viscosity of the fluid, etc) and is far from easily predictable.

A "durso" or "stockman" may fully open channel if the pipe is large enough in relation to the volume of flow. In this mode, the air entering the standpipe has no effect on the volume of flow and the only turbulence is that created by the walls of the pipe. The net effect is near silence, unless the walls of the pipe cause the water to tumble. In that case, you hear water running.

Sadly, MOST folks who run a "durso" or "stockman" push enough flow through them that they enter two-phase flow. In this scenario, the water falling through the pipe blocks enough of the diameter that a negative pressure (suction) is created by the falling mass of water. Allowing less air to enter the pipe allows more water to flow and allowing more air to enter the pipe allows less water to flow (again by displacement of water by air and by increased turbulence). At the upper end (almost no air) the system is usually silent. As the rate of air entrainment increases, the rate of ejected tiny (you folks call them microbubbles) increases and the noise of the system increases. At some critical point, the two phase flow becomes so turbulence that the air begins to chug and gurgle.

What one may consider "issues" another may not. Each of us has different expectations and goals with regard to system performance and each of us defines "acceptable" in a different manner.

With all due respect to Richard Durso and/or Ken Stockman, both of them stumbled upon a setup that worked for them and has helped many others move toward peace with regard to their overflow problems. That reality does not allow their standpipes to defy physics nor does it give scientific credence to their explanations of why they think their systems work as they do.

Certainly if and when everything works out, the system (air assisted standpipe) can run very well. This problem is that rarely does the return pump rate, pipe configuration head height match up to get a quiet, somewhat bubble free and stable system. For those that do stumble upon this Zen, life is wonderful For those that don't, the overflow is a nightmare.

From a safety standpoint, most folks do not understand that an air assisted standpipe running anywhere near its full siphon capacity will fail (flood the system) if there is any type of blockage or increased airflow (thus reducing standpipe throughput). That is, if you have to almost block the air off to get the standpipe to keep up, then it is a disaster waiting to happen. Air assisted standpipes are best (safest) used when the flow through them is open-open channel or on the two-phase side closer to open channel flow.

So can a 1" durso handle 600GPH... sure, in some setups where the head heaght, pipe diameter, back pressure, fitting configuration, etc. all play nice. In another system it may sound like a toilet or 2 headed slupring monster

You can't cheat the physics


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