Sprinkling and Fogging System

Technology HighlightsNov 9, 2011

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Eran Luckatch – International Sales Manager.

As a company that offers comprehensive solutions and excels in Turnkey Projects, and among the supplementary systems offered by Azrom, we also offer a variety of solutions for reducing temperatures and increasing humidity levels in the greenhouse.

One of the most effective means for reducing temperatures and increasing humidity levels in the greenhouse is the use of a fogging system.

Cooling the air inside the greenhouse by using foggers is based on the exchange of energy between the air and the humid fog created by the foggers (sprinklers). The drops of water absorb the hot air, at a rate of 590 calories per gram of evaporated water. This process cools the temperature of the air and increases the humidity level inside the greenhouse.

Proper installation, correct spacing between the sprinklers and effective operation can lead to a drop in the internal temperature of the greenhouse of between 4-7 degrees Celsius, depending on surrounding conditions.

The efficiency of the cooling system in the greenhouse depends upon two factors:

  • The external temperature
  • The external humidity level

Fogging at a rate of 2-3 mm per hour usually results in proper cooling (equivalent to 20 cubic meters per hour per hectare).
There is usually a 10 second interval between rounds of fogging.
The length of the fogging round depends on the velocity of the air movement within the greenhouse, which is dependent upon and determined by the type of ventilation system installed in the greenhouse.

For example:

Wind Velocity Length of Interval Length of Fogging
0.1 meters per second 10 seconds 1-2 seconds
0.5 meters per second 10 seconds 3-5 seconds
1.0 meters per second 10 seconds 10 seconds

In order to monitor and coordinate the length and pace of fogging in the greenhouse, a control unit for controlling the sprinklers must be installed. This control unit operates in coordination with internal temperature and humidity levels.

Due to the short intervals between fogging rounds, the sprinkler is equipped with a device that prevents dripping, in order to ensure its proper and rapid operation.

A fogging system that sprays 2.5 liters per hour at a pressure of 4 bars will emit drops of mist that are approximately 20 microns in size. Water drops of this size evaporate quickly and do not drip down onto the leaves of the crops or onto the floor of the greenhouse.

The installation of a fogging system with these coordinates (one that sprays 2.5 liters per hour at a pressure of 4 bars), entails the following:

  • Distance between the rows of sprinklers: 3 meters
  • Distance between sprinklers along the row: 2 meters
  • The sprinklers should be installed as high as possible above ground level.

Increasing humidity levels by using a fogging system:
If we are interested in increasing the internal humidity levels, we must first turn off the greenhouse ventilation system. The length of the fogging session must be as short as possible (1 second).

The intervals between fogging change, depending on the desired level of relative humidity. For example: In the morning, when temperatures begin to rise and the humidity level starts to fall, the humidity/temperature sensor will operate the fogging system.
Determining the intervals between fogging, according to the following criteria:

Desired Humidity Level Length of Interval Length of Fogging
30% – 40% 60 seconds 1 second
40% – 50% 90 seconds 1 second
50% – 60% 120 seconds 1 second

Azrom is currently one of the world’s leading companies for the production of greenhouses.

Every project, anywhere in the world, receives the proper, individual consideration, combining: local characteristics, design and planning, agronomic consultation, examination of growing conditions, construction and the planning of supplementary units and systems, including electricity, water, heating, trellising, climate control and fertilization. Only an overall, comprehensive solution, be it simple or complex, is the perfect response.

The company’s quality control policy focuses on the supply of qualitative products for long term client use under difficult and challenging field conditions.

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