Venturi is used for fertilizer & chemical injection through drip irrigation system. Venturi fertilizer injectors are the most efficient and economical way to feed liquid nutrients to the roots of the plants through drip irrigation system. Fertigation is being done simultaneously along with irrigation.

Venturi injector is a tapered constriction faucet which operates on the principle that pressure drops accelerate the change of velocity of the water as it passes through the constriction.

How does the Venturi work?

A Venturi is a system for speeding the flow of the fluid, by constricting it in a cone shaped tube. In the restriction the fluid must increase its velocity, reducing its pressure and producing a partial vacuum. As the fluid leaves the constriction, its pressure increases back to the ambient or pipe level.

They work on the principle of differential pressure. Water enters the venturi at a higher pressure than it exits. The difference in the entry and exit pressures creates a vacuum at the suction port on the side of the venturi. The bigger the difference, the greater the vacuum and therefore the efficiency of the mixing.

How to use Venturi?

The injector starts working when the auxiliary valve that has been installed in the suction hose opens. To achieve that the suction effect is generated, we must partially close the valve that regulates the pressure of the main line until the device’s own flow has been generated. If we tried to close the valve after this point, the pressure in the irrigation system would decrease. If what we want is for the system to end, it is only necessary to fully open the pressure regulating valve and close the auxiliary valve.

Installation Tips

  • Always keep in mind that a Venturi Injector should always be installed in a horizontal or vertically upward position and in the direction of flow (flow arrow marked). Installation in a vertically down position may cause intermittent or erratic suction by the injector.
  • Always use “full flow” valves and fittings when connecting to a venturi injector. Never use pipe fittings smaller than the thread size of the venturi injector. (We recommend buying the side fittings from the same company)
  • Do not over-tighten venturi injectors when fixing them to pipes or fittings. The use of a thread sealant/tape is recommended.
  • Venturi injectors require a pressure differential to operate properly. Normally, the outlet pressure must be at least 25 – 30% less than the inlet pressure for significant suction to occur.
  • Pressure gauges are recommended to determine the actual pressure difference.

Choosing a Venturi System

When selecting a venturi fertilizer injector, choose a size and model that matches your drip irrigation system. Always select an injector that matches your irrigation flow rate. Generally, a small sized injector system will restrict flow of the system., while an oversized system will have difficulties drawing fertilizers into the irrigation system. A venturi fertilizer injector system includes a bypass, pump and a suction assembly.

Venturi injectors come in different sizes from ½’’ to 2’’. However, ½’’ and 3/4’’  are the most popular and readily available.

What to consider while purchasing a venturi injector

  • Maximum pressure at the Pump/ Head Unit installed in the field.
  • Field pressure at which the drippers/sprinklers are running in the field.
  • See the performance chart and check the inlet and outlet pressure available in your field for the right selection.
  • Assessing the performance of the venturi injector at very less pressure difference between inlet and outlet.
  • Buying the venturi according to the requirement of injection rate at the inlet and outlet pressure.
  • Select the venturi injector having a check valve at the suction port.
  • Buy the venturi injector with their side assembly from the same company, don’t try to purchase and assemble the parts from different companies.


Venturi System Prices

Size(s) Prices(KES)
1/2 2000
3/4 3000
1” 3500
2” 5000


Advantages of a venturi fertilizer injector

  • Has uniform injection rate from start to finish
  • You can regulate the rate of flow of fertilizer or chemical
  • Venturi is very cost effective as there is no energy. Labour is drastically reduced
  • Quick and easy installation.
  • Zero maintenance cost

Maintenance of Venturi injector

The injector can be cleaned with the following steps:

  • Pour 5 litres of water into a 20 litre bucket.
  • Pour 1 litre of Pool Acid into the bucket – ALWAYS ADD THE ACID INTO THE WATER. (“Pool Acid” is Hydrochloric Acid or Muriatic Acid. Typical ” Pool Acid” is about 30% acid).
  • Place the injector in the bottom of the bucket and allow it to soak for 1 hour.
  • Rinse the injector with fresh water and place it back in service.
  • When finished cleaning the injector, fill the bucket with water and dispose of it properly.


By selecting of reputed brand’s Venturi injector and with correct installation, the farmer will get benefits in terms of life of the venturi injector, less operational problems, reduction in the system running cost, more area to irrigate because of less throttling of line and uniform distribution of fertilizer to the crops which will lead to higher crop yield. For any inquiries contact Mazero Agrifood on +254729777711.

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