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| Guidelines for handling and installation
of film: |
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| Instructions for storage of film:
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| The films must be stored on a smooth surface
in horizontal position in an enclosed shade, out of exposure
to direct sunlight. |
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| Guidelines for greenhouse structure |
Metal tubes / Pipes:
The metal tubes / pipes must be clean, polished and properly
zinc galvanized. The angles & radius of the tubes should
be well designed to give uniform tension across the film. The
structure should give enough support so that there is no flapping
of the film.
Wooden framework: The
wood should be devoid of any sharp or protruding edges and must
have a smooth surface. Before selecting the type of wood, one
should ensure that it does not excrete any substance, which
is detrimental to life of the film. (e.g. pine wood must be
avoided).
Ensure that the framework is sturdy especially at the joints.
If any components are loose or broken they ought to be rectified. |
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| Preparations before installation
of film |
It is recommended that slats/locking channels/grippers
made from aluminum are used instead of the ones made from PVC.
Enough slats/grippers must be provided to be able to follow
the contour of the arches avoiding sharp edges/bends. They must
be tightened so that they do not move against the film.
All metal or wooden parts that are in contact with the film
must be painted with a white acrylic-based paint. |
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| Installation of the film |
While installing the multilayer film,
first ensure that the respective layers are facing the right
direction (i.e. inside or outside) as shown on film or instruction
supplied along with the film.
It is advisable to keep a sample piece of 0.5 m2 or 2 ft2 along
with the manufacturer’s identification mark.
The film should be installed in early hours of morning on mild
days when the ambient temperature is cooler (15-23OC) and there
is no wind. When positioning the film it should be tensioned
tightly enough so that there is no flapping of film on windy
days.
Attention should be paid that proper care is taken so that the
film is not damaged or torn during installation especially at
the time of stretching across. The ideal method is to place
film on the top and unroll along the length of greenhouse any
other method should be avoided. |
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| Protection of film |
White acrylic-based paint must be applied
on the film wherever it comes in contact with the construction
frame of greenhouse. If not, the film becomes warmer in the
contact areas and is prone to faster degradation.
Old structures / Structures have to be taken care specially,
as because due to high accumulation of rust, and it is a well
known fact that higher concentration of ‘fe’ i.e.
iron found in rust form, on the film is detrimental for the
life of plastic. |
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| Ongoing maintenance of film |
Any holes or tears must be repaired immediately
with a special adhesive tape (non PVC) designed for application
in polyethylene films.
Whenever required the film, should be re-stretched between the
seasons or after strong winds so as to maintain the even tension
of the film. |
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| Ventilation and irrigation |
The greenhouse must be suitably aerated,
especially in summer season even if it is empty. This is to
prevent overheating of the greenhouse. The area provided for
ventilation should be at least 20% of the ground surface.
The greenhouse must be irrigated once a week even when there
is no cultivation within so as to maintain the humidity within
the structure. A drastic drop in relative humidity has a negative
effect on the life of film. |
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| Crop Protection Chemicals (CPC) |
| Crop Protection Chemical’s based
on Halogens or Sulphur has a catalytic effect on the degradation
process of film. Hence any direct contact of CPC’s with
the film should be avoided. |
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