Siphon: 7 Powerful Applications, Meaning and Working [PDF]

In this article, we shall be covering the definition, working principle, and applications of a siphon. We have also provided a PDF download link for the same.

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What is siphon?

A siphon must have a longer outlet leg below the short leg inlet elevation to allow the weight of the liquid in the longer leg to create suction which causes the liquid to flow down and out the siphon end.

This has a greater volume of liquid in the long leg than it has in the short leg. The weight of the liquid in the long leg is acted upon by gravity and when the liquid flows out from the end of the airtight siphon conduit, vacuum suction is created and the tube draws liquid up the short leg and over the crest to the outlet.

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Siphon Meaning

Defination: It is a long bent pipe that is used to transfer liquid from a reservoir at a higher elevation to another reservoir at a lower level when the two reservoirs are separated by a hill or high-level ground as shown in the figure below.

Siphon working principle

Purpose of siphon

  • To transfer liquid from one container to another without the need for pumping or mechanical aid.
  • To empty a container or reservoir that is located below the level of the outlet or drainage point.
  • To create a negative or vacuum pressure in the system, which allows liquid flow against gravity.
  • To control the flow rate of liquids in a system is determined by the height difference between the inlet and outlet points.
  • To avoid contamination liquid is prevented from coming into contact with air or other substances during the transfer.
Purpose and applications of siphon
Photo By TurboSquid

Working Principle of Siphon

Point C which is at the highest of the siphon is called a summit. As point c is above the free surface of the water in tank A, the pressure at C will be less than atmospheric pressure. Theoretically, the pressure at c may be reduced to -10.3m of water, but in actual practice, this pressure is only -7.6m of water or 2.7m of water absolute. If the pressure at c becomes less than 2.7m of water absolute, the dissolved air and other gases would come out from the water and collect at the summit. The Flow of water will be obstructed.

Video by ZaksLab

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Application or Uses of Siphon

  • Transferring liquids between containers or tanks, such as fuel from a gas can to a vehicle.
  • Emptying water from a swimming pool, aquarium, or other large vessels.
  • Draining fluids from machinery or equipment, such as oil from an engine or coolant from a radiator.
  • Filling containers with liquid from a larger reservoir, such as filling a bottle with water from a large jug.
  • Controlling the water level in irrigation systems or fountains.
  • Maintaining a constant level of liquid in a system, such as a carburetor or a humidifier.
  • Removing excess water from flooded areas or basements using a sump pump with a siphon hose.


Define Siphon In Simple words

A siphon is a tube or pipe that allows liquid to flow from a higher level to a lower level without the need for pumping or external force. This happens because the liquid is pulled down by gravity and the pressure difference between the two ends of the tube. It’s commonly used to transfer liquids from one container to another, such as the suction of gasoline from a car’s tank or draining water from a fish tank.

How to Siphon Gas Steps

  • Get a long siphon hose that is suitable for gasoline.
  • Insert one end of the hose into the gas tank from which you want to withdraw gas.
  • Keep the other end of the hose outside the tank and place it in the container where you want to transfer the gas.
  • Make sure the end of the hose in the gas tank is at the bottom of the tank and not floating on the surface of the gas.
  • Create a suction by sucking on the end of the hose that’s outside the tank until the gas starts to flow.
  • Once the gas starts to flow, remove the hose from your mouth and let the gas continue to flow through the hose.
  • If the container you are transferring the gas to is higher than the gas tank, make sure the end of the hose in the container is at the bottom, so the gas continues to flow by gravity.
  • Once you have withdrawn the desired amount of gas, remove the hose from both the gas tank and the container, and let the gas finish flowing.
  • Dispose of the siphon hose properly and wash your hands thoroughly to remove any gasoline residue.
How to Siphon gas steps wikihow
Photo By Wikihow

Is Siphon and Psiphon 3 same

No, Siphon and Psiphon 3 are not the same. It is a tube or pipe that allows the transfer of liquids from a higher to a lower level using gravity and pressure differences. On the other hand, Psiphon 3 is a free, open-source internet censorship circumvention tool that provides access to blocked websites and content. It is a software application that runs on a computer or mobile device.


In conclusion, a siphon is a simple yet effective device that is used to transfer fluids from one container to another without the need for pumps or external power. It operates on the principle of gravity and atmospheric pressure and can be used to transfer many types of fluids, including water, gasoline, and even beer. Its applications are widespread, ranging from irrigation systems to brewing beer to fuel Supply systems in petrol engines.

However, it is important to note that it can be dangerous if not used properly, and appropriate safety measures should be taken to prevent injury or damage. Overall, It is a versatile and reliable tool that has been used for centuries and will likely continue to be used for many years to come.


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