Naturally, for many people, the concept and inner workings of a siphon system are not something they are familiar with.
The below information is intended to help the average layman understand the principles of successful siphoning and in turn, why our product is so innovative and effective.
We invite you to read through this information and request a demo.
What is a siphon?
A way of draining water using just gravity and a leakproof pipe.
How does a water siphon work?
A siphon uses a pipe, just like a drainpipe. But it must be leakproof pipe just like a water pressure pipe is.
Instead of the pipe being laid downhill, it is run uphill, into an arch and then downhill again – and this allows it to still have the water flow out on its own!
The water is drawn upwards and then downwards as part of the liquids journey from a higher place to a lower place at the end.
Some common examples of siphoning –
Most of us are familiar with siphoning out the top of containers over relatively small heights for example, with a fish tank, spa pool or getting fuel out of a vehicle.
Is siphoning used commercially on large-scales?
Yes, definitely.
Simple siphons have been used extensively for assisting in some types irrigation.
Typically they are used for modest heights – say 1 or 2 m.
Siphoning over greater heights (2 – 9 m) is not easy or common, but it is achieved successfully by specialist dewatering & siphoning companies.
Why is it so hard to siphon to maximum heights?
The main issue is cavitation – the accumulation of bubbles in the pipe that upset the siphon flow.
Removing these bubbles becomes much more difficult when siphoning over greater heights.
Is siphoning the same as drainage?
Water in a river naturally flows from a higher point to a lower point i.e. drainage.
It’s the same for a man-made trench or conventional drain where gravity is causing the water to flow to a lower place.
It’s also the same for a siphon, gravity is moving the water but it’s not always travelling downwards like the river, trench or conventional drain.
It starts by travelling in a pipe up and then down – down below the level that it started at.
As in the lower half of the diagram, quite quickly the water level between the source and the outlet will become identical – just like a water level.
So, yes – a siphon is a drain, but it works in a different, man-made way.
What do I need to know to use a siphon?
Here are some guidelines for siphons to work –
- The end of the downhill pipe must be below the top of the liquid going into the pipe
a. Note – the more it is below, the faster the water will flow
b. The vertical difference between the water level at the intake and the water level at the output is what causes the flow (the fall). It’s just like a river or a drain trench – the deeper, the faster. - The whole pipe must be full of water & free of air – both the uphill and the downhill. Some bubbles may get stuck at the top, between uphill and the downhill pipe. This can slow or even stop the flow of water in the siphon pipe. If the water is flowing fast, then bubbles may be carried all the way through and out the pipe.
- The maximum height that a siphon can lift over is nearly 10 m at sea level.
At higher altitudes it is less because the air pressure decreases as altitude increases. - Note – the water pressure in the arch of the siphon pipeline is actually negative not positive – it is a vacuum. If you were to have a hole or a valve in the arch, it would suck air in, and not squirt water out.
a. The negative pressure increases closer to the top of the arch.
b. The negative pressure is greatest at the top of the arch. Say 14.7PSI at sea level i.e. less as altitude increases.
How does conventional drain compare to siphon draining?
What are the differences –
There are several significant differences between conventional drainage and siphon drainage.
Fundamentally it is because siphon drainage doesn’t just drain water downhill – it moves the water – up, out, and over to another location.
Siphon drainage doesn’t just deal with the unwanted water near the soil surface, it can work much deeper. So is able to influence and manage the water table.