Herbie or Bean Animal overflow question

[grouper therapy]

In all the information I've found on the internet it is always suggested that the outlet from those overflow be submerged under the water but no more than 1/2". Now I know why no more than 1/2" so as to allow air to escape but why submerge at all? Is it just for the noise? A siphon works with the other end exposed. Right? What am I missing ?

 

[seth the wine guy]

Dave, I don't know the physics of why it is what it is, but, I've played around with a lot of configurations with my BA. I'm able to turn more GPH through the tank with the tubes submerged at the discharge. If I don't have them submerged, my DT overflows.
IME Submerged tube = greater flow/discharge

 

[grouper therapy]

Seth The Wine Guy;1059128 wrote: Dave, I don't know the physics of why it is what it is, but, I've played around with a lot of configurations with my BA. I'm able to turn more GPH through the tank with the tubes submerged at the discharge. If I don't have them submerged, my DT overflows.
IME Submerged tube = greater flow/discharge

Hmmm.logically you would think the opposite. No restriction more flow. Maybe being submerged pukka on the flow some how.
Thx for your observation!

 

[jbdreefs]

I can make up a hypothesis!

The siphon drain is constricted at some point. The amount of water flowing through the pipe, post valve, is not enough to fill the entire pipe. Therefore, with an un-submerged discharge, air can contine to enter the pipe. If the discharge is submerged, the air in the pipe eventually flushes out and is replaced by more water. The extra water creates more "pull" post the valve and increases the siphon at the other end.

Maybe?

 

[mikesmith34]

JBDreefs;1059171 wrote: I can make up a hypothesis!

The siphon drain is constricted at some point. The amount of water flowing through the pipe, post valve, is not enough to fill the entire pipe. Therefore, with an un-submerged discharge, air can contine to enter the pipe. If the discharge is submerged, the air in the pipe eventually flushes out and is replaced by more water. The extra water creates more "pull" post the valve and increases the siphon at the other end.

Maybe?

Bingo

 

[porpoiseaquatics]

JBDreefs;1059171 wrote: I can make up a hypothesis!

The siphon drain is constricted at some point. The amount of water flowing through the pipe, post valve, is not enough to fill the entire pipe. Therefore, with an un-submerged discharge, air can contine to enter the pipe. If the discharge is submerged, the air in the pipe eventually flushes out and is replaced by more water. The extra water creates more "pull" post the valve and increases the siphon at the other end.

Maybe?

+1. I did an experiment with clear tubing once. What I found is lower flow when air could enter the hose. Once I removed the air and the tube completely filled with water, I got a substantial increase in flow rate.

 

[Adam]

That is correct. The amount of restriction at the valve plays a roll too. But in the end so does the length of "dry pipe". I say dry pipe because if you extend the pipe too far below the surface of the water level in the sump the depth of the water puts pressure against the end of that pipe. This will reduce flow to an extent as well. This all why there's a 1/2" rule.

This is generally based on an under tank sump. For one that is dropping to a lower floor like a basement going further into the sump won't effect it much due to the longer length of pipe. But it would be worse in this case if the pipe didn't extend down that 1/2". Most installs will have the valve closer to the DT...

 

[Adam]

At least that's what she said 😉

 

[grouper therapy]

So what if there is no valve? What if the valve is at the sump, 2" before the waterline? What if after the valve there is no hose?

 

[grouper therapy]

I would think that the height of the entrance to the siphon in relation the water line above would be the determining factor for flow . Head height = more pressure?

 

[jbdreefs]

I won't say it is impossible, but I doubt either of these systems would be very feasible, from a reliability and perform as intended perspective, without a valve.

If the valve is that close to the sump water line, I would anticipate very little effect on performance in regards to total possible flow.

 

[grouper therapy]

I say it makes no difference. The valve only assure a continuing siphon by restricting flow so the water level in the box stays high enough not to allow air in. That could be done with more flow to the box(not the safe way). I can tell you this a test will be done today.

 

[Adam]

There are a lot of variables. Diameter of the pipe, length of the drop... Other than the negatives. Noise, splashing, more salt creep, etc... Generally in those cases it would have a negligible, if any, effect.

 

[hzheng33]

for whatever it's worth, this was shares with me from Grant. For clarification, we are talking about the 1/2 inch difference between the water level and the wiers, correct?

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[Adam]

grouper therapy;1059189 wrote: I would think that the height of the entrance to the siphon in relation the water line above would be the determining factor for flow . Head height = more pressure?

We're only talking a few inches over the top of the siphon. This has no real effect in increasing the amount of flow. It's gravity's effect on the water in the pipe that does that. In a vertical drop the longer the pipe the more water is on that pipe. More water = more weight = more flow.

grouper therapy;1059197 wrote: I say it makes no difference. The valve only assure a continuing siphon by restricting flow so the water level in the box stays high enough not to allow air in. That could be done with more flow to the box(not the safe way). I can tell you this a test will be done today.

Yes that is somewhat correct. But when your restricting flow with the valve if the bottom of the siphon pipe isn't submerged you're giving the opportunity for air to enter the pipe as the flow is reduced there to the point that air pressure is more than the water pressure. This is hard to explain in text typing on my phone. It's the same principle as the class room experiment with a glass of water and a piece of paper and turning it upside down. It's the air pressure and vacuum that keeps the water in the glass.

 

[enderg60]

Yes, you can maintain a siphon with the end of the tube open to the air. But if your power goes out for a short period (brown out or just for a few minutes) and the outlet is open to the air it will start to drain out and let air in which will break the siphon.

If it starts back up again you have to purge the air out of the siphon tube. If the outlet is submerged and the power comes back on before the tank fully drains(to below the overflow level) then the siphon wills start back up no problem.

I actually built a drain collector for my bean setup so I can use the drain for an algea scrubber and still maintain siphon during power outages. It was a huge PINA to restart and re-tune a siphon drain when you have to run to the basement and back to make adjustments.

 

[grouper therapy]

anit77;1059215 wrote: We're only talking a few inches over the top of the siphon. This has no real effect in increasing the amount of flow. It's gravity's effect on the water in the pipe that does that. In a vertical drop the longer the pipe the more water is on that pipe. More water = more weight = more flow.

Yes that is somewhat correct. But when your restricting flow with the valve if the bottom of the siphon pipe isn't submerged you're giving the opportunity for air to enter the pipe as the flow is reduced there to the point that air pressure is more than the water pressure. This is hard to explain in text typing on my phone. It's the same principle as the class room experiment with a glass of water and a piece of paper and turning it upside down. It's the air pressure and vacuum that keeps the water in the glass.

EnderG60;1059225 wrote: Yes, you can maintain a siphon with the end of the tube open to the air. But if your power goes out for a short period (brown out or just for a few minutes) and the outlet is open to the air it will start to drain out and let air in which will break the siphon.

If it starts back up again you have to purge the air out of the siphon tube. If the outlet is submerged and the power comes back on before the tank fully drains(to below the overflow level) then the siphon wills start back up no problem.

I actually built a drain collector for my bean setup so I can use the drain for an algea scrubber and still maintain siphon during power outages. It was a huge PINA to restart and re-tune a siphon drain when you have to run to the basement and back to make adjustments.

Sorry that doesn't seem logical. The air will enter the tube from the top side regardless of the other end. it being submerged on the other end will not prevent air from entering the other end during a power outage. The air will purge easier if not submerged.
So far the only logical reason for it to be submerged is sound. The air thing doesn't jive.

 

[grouper therapy]

anit77;1059215 wrote: We're only talking a few inches over the top of the siphon. This has no real effect in increasing the amount of flow. It's gravity's effect on the water in the pipe that does that. In a vertical drop the longer the pipe the more water is on that pipe. More water = more weight = more flow.

Yes that is somewhat correct. But when your restricting flow with the valve if the bottom of the siphon pipe isn't submerged you're giving the opportunity for air to enter the pipe as the flow is reduced there to the point that air pressure is more than the water pressure. This is hard to explain in text typing on my phone. It's the same principle as the class room experiment with a glass of water and a piece of paper and turning it upside down. It's the air pressure and vacuum that keeps the water in the glass.

Inaccurate twice the height equates to twice the head pressure , up or down. The size of the opening it exists however will max out eventually no matter the height.

 

[grouper therapy]

Ok guys after several trials with each scenario here are the results
3/4" bulkhead 3/4" thin wall pvc and 3/4" true union ball valve 84" to the top of the waterline in the tank. 72" to the opening in the bulkhead.
time to fill 5 gallon bucket
discharge under water 59,57,61 seconds
discharge out of water 57,56,59 seconds

no pipe after true union valve 58 ,59,60 seconds
Now with a 6" standpipe in bulkhead reducing the distance to the waterline by 50%
e.
discharge under water 68,70,75 seconds
discharge out of water 69,71,74 seconds.

So I deduct the only difference was the taller standpipe in the overflow,which reduced flow around 10-15%
I would like to see how much 18" difference would be.
The discharge under water or out made no difference

Also the difference in height after valve seemed to have very little impact either.

 

[Adam]

grouper therapy;1059272 wrote: Inaccurate twice the height equates to twice the head pressure , up or down. The size of the opening it exists however will max out eventually no matter the height.

You're confusing head pressure for pumps and water weight over an open pipe. Water only weighs 0.036127lbs per cubic inch. So if you have 5" over the top of the siphon pipe there's 2.89 ounces of weight over the entrance of the pipe. If you double the height you still don't even have a quarter pound of pressure. Granted this is a generalization you can see we're not talking much in the over flow box.