Affnan's Valve - A Detailed Explanations of A Simple Item

Foreward

First of all I would like to point out that, siphon had been around for a long time dated few hundred years ago. Siphon usage ranging from transferring fluid from one container to another right to flushing the toilet.

Most usage of siphon involved a fixed amount of fluid to be transfer to another container, such usage of siphon don't require it to be operating continuously without human intervention. Toilet flush for example require human input to create the flushing effect from a siphon mechanism, and the flushing stop when cistern is depleted of water. Continuous operation of these siphon are not needed.

In Aquaponics due to the nature of system arrangement, continuous operation of siphon is necessary with constant water flowing into the container. Siphon drawing water out creates "Flood and Drain" cycles that promote Aquaponics balance.

No one living today could claim have invented the siphon, nor claiming pattern for such. However improvement to siphon design to make it reliable or use able to an application can be considered as an Innovation. An Innovation deserve to be recognized if its significantly change the way things being done.

I like to compare, a redesign Siphon to that of a shoe. Shoes has been invented long time ago, however shoes the late Micheal Jackson use for his moon walk was design by him and accepted as a pattern. He may not invent the shoes but he make it better to suit his purpose.

Here it come !!

Explanations that follow below are the results of two years of experimenting and studying the siphon... eight months of experimenting with endless siphon design, most siphon have been tried until this current design is met, and the remaining months to refine the design and understand it principle to tweak and tune it for better function.

What you will find below are the way to make this valve, how to adapt it to your setup and some simple task to do in the event it fail after deployment. A lot of effort was put into this and it would give me great satisfaction if you succeed in using it for your system.

This is the schematic of my bell valve.

I will slowly add here the write up, on how the Siphon function and the various adjustment done to make a siphon function as it did.

Before I proceed in explaining how mine work, let us have a look at the basic stand pipe siphon below and the various method used in an attempt to make it use able in Aquaponics. This is the baseline design for a siphon, what needed to be done is to make changes to this basic design to make it better.

In order to make improvement we must know what are the variables involved in a siphon and how can these variable be change to cause a change in the siphon behavior.

In this basic siphon to get the siphon action started is just a matter of getting water flow into the growbed or container large enough to cause the siphon action. Water flow in rate requires to start this siphoning is directly proportional to the size of the stand tube. Therefore starting a siphon is easy, what difficult is to cut-off that siphon action once water is drained out.

It may appear easy, people that has never make a siphon may think once water is drained out and the siphon will draw air and cause the siphon to stop. However that is not the case with an Aquaponics setup, which has continuous water supply coming into the grow bed.

This water flowing into the bed earlier which much needed to cause the siphon is now the problem in causing this siphon to cut-off. This continuous water in which cause the siphon to refuse to stop and continue to draw water out is call the "Equilibrium Flow".

This is the killer of siphon.

Why do equilibrium flow happen ?

It happens because the water needed to start the siphon is the same or more then that require to sustain a continuous flow.

How do we stop equilibrium flow ?
To stop this equilibrium flow few things needed to be done:

• Ensuring the difference between water flowing in to make a siphon and water needed to sustain a continuous flow large.
• Ensuring water flowing out of the siphon at the end of cycle (residual flow) will still be strong enough to pull in air causing the break.

How do we achieve this ?

• We have to make a siphon to start with less amount of water flow in, to that of the same size basic siphon.
• Make a siphon with strong residual flow.

Which would make the difference above large enough to ensure no continuous flow is maintain.

But its not a car !

Tuning a siphon is very much like tuning a car for better mileage. To get better gas mileage its a combination of items need to be check or adjusted, fuel air mix adjusted, spark efficiency, timing accuracy and to the extend that tire pressure need to be check. This cumulatively make a car more efficient thus improving mileage.

In a siphon, multiple factor are involved to make it efficient and thus reliable. Some if not all these factor need to be improved to ensure trouble free operation.

Below are various methods use to help this happen and to certain extend helps in achieving this objective.

How do bell siphon achieve this ?

This is a long explaination and thank you for reading it.

Below are variations of my valve. Valve A utilize the elbow, Valve B slight restrictor and Valve C with a longer down tube. All these difference variations do one function, aid in producing siphon action with lesser amount of water flowing in. These various modification to the outlet are part of the tuning for a reliable siphon.

More alteration needed to be done to ensure the margin of flush and equilibrium flow is widen.

Bernoulli's Theorem, Theory of Flight and the lowly siphon

I work in the aerospace industry for almost 30 years, from day one we were taught about the Bernoulli's Principle and on how lift achieve with this principle. I apply this to the valve design to do what it need to do, to create an earlier flushing Siphon.

Extract from : http://www.centennialofflight.gov

Bernoulli's Principle is a physical phenomenon that was named after the Swiss scientist Daniel Bernoulli who lived during the eighteenth century. Bernoulli studied the relationship of the speed of a fluid and pressure.

The principle states that "the pressure of a fluid [liquid or gas] decreases as the speed of the fluid increases." Within the same fluid (air in the example of aircraft moving through air), high-speed flow is associated with low pressure, and low-speed flow is associated with high pressure.

This phenomenon applies to the lift produced by the wing of an airplane, i.e., an airfoil. The airfoil is designed so that the air moves more rapidly over its upper surface than its lower surface, thereby decreasing pressure above the airfoil. At the same time, the impact of the air on the lower surface of the airfoil increases the pressure below the airfoil.

This difference between the decreased pressure above and the increased pressure below produces lift. Thus, a wing with more curvature on the top surface (greater camber) has greater lift than a wing with flat surfaces.

Apply the Bernoulli's Theorem to the siphon, this is what you get. There is more to it than just this.

Bernoulli's effect will cause siphon to occur with less water flowing (strong initial flow) and strong residual flow couple with offset stand tube contour to produce unbalance water column and finally the outlet restriction or interference causing even lesser water flowing needed hence assisting siphon lower flow starting and equilibrium flow termination.

Above statement takes into account about 4 or 5 different variables to ensure reliable siphon.

Lower flow siphon starting are due to :

• Strong initial flow in siphon - Bernoulli's Effect
• Outlet restriction or interference
• Longer Exit down tube length - if installation permit

Equilibrium Flow termination assisted by :

• Strong residual flow - Bernoulli's Effect
• Unbalance stand pipe exterior water column due to its funnel shape
• Longer Exit down tube length - if installation permit
• Volume Ratio between Stand Pipe exterior water column within the bell to that inside the standpipe and outflow, more in the stand pipe the easier to cut off.

Making the funnel wider on the top should make it better and making the stand pipe length tall also have same effect on valve to make water cut off easier. Then there will be a limit to the height of the grow bed that prevent this arrangement, but wider funnel is do able.

To improve further this design, what needed is to make a smooth funnel for the Bernoulli's effect to be maximized.

This is to the extend that I will explain it, going deeper would require mathematical calculation and formula which I feel not necessary at this point.

My intention is to have this valve easily made by anyone to such an extend that no one could capitalize on it since its so easily made.

What else to be tested ?

I would like to try out the valve below;

• Valve A is base on the outer stand tube column offset only to cause water unbalance.
• Valve B was mentioned by simo@backyardaquaponics.com that having a pin hole to have air leaked in the bell may assist in water cut off.

These on their own, may or may not be sufficient to cause the much needed equilibrium cut-off.

Check here on how to make the : Mini Version

Check here to see the revised siphon : Part 1 , Part 2 , Part 3 , Part 4 - Final

Updates : 6th September 2010


This siphon outlet attachment is made for high water situation on my set. This siphon outlet will provide aeration with high water level and silencing of siphon outlet at lower water level and it can be view here for the completed work. 


Simplified diagram as below.

Updates : 18th March 2013

In this installation Here I remove the bell and use the outer strainer as the bell itself.