How to Improve the Transmittance of Greenhouse Film?
1. Methods for improving the transmittance of greenhouse film
(1) Remove external dust
During the use of greenhouse film, some measures taken by vegetable farmers are not conducive to the removal of greenhouse film dust. To give two typical examples: one is a shed that uses a grass curtain as a cover. The grass curtain itself has poor dust absorption, it does not have a good sweeping effect on the dust on the greenhouse film. The shed membrane is covered with holes and the shed membrane with holes will condense with the dust on the outside of the membrane due to the moisture in the shed, so that the dust is not conducive to removal. The second is to add a layer of film on the bottom of the cover, so that the pollution of the greenhouse film is more serious, the dust has a stronger adhesion to the film after moisture absorption. It is not easy to remove naturally with the wind and precipitation.
(2) Eliminate internal droplets
The inside of the greenhouse film is prone to dew condensation. If the anti-fogging and dripping properties of the greenhouse film are poor, a large number of water droplets accumulate on the greenhouse film, which will refract the light, so that the direct light originally transmitted through the greenhouse film becomes scattered light. Generally speaking, PE, EVA, PVC films can be added with anti-fogging and dripping agents. During winter use, the greenhouse film has a good anti-fogging and dripping function, the grouting film generally does not add anti-fogging and dripping agents. Condensation and dripping in sheds using grouting membranes in winter are relatively serious. Of course, the anti-fog droplets on the greenhouse film have a shelf life. Generally speaking, the shelf life is about 3-6 months. When the dissipation of the defogging and dripping agent disappears, the greenhouse film will lose its dripping function. Therefore, no matter it is the choice of the greenhouse film or the period of use, it is necessary to ensure that the anti-fog flow performance of the greenhouse film is at the optimal period.
2. Detection method of greenhouse film transmittance
Agricultural greenhouses are mostly produced in the spring, when the temperature is low, the light is weak for a short time. High and stable light transmittance is important for the indoor temperature and the photosynthesis of crops, so the new greenhouses are generally required to be transparent. The light transmittance is more than 90% and the light transmittance of the greenhouse film used for more than 5 months is more than 55%. It is generally recommended to use the LS116 transmittance meter to detect the light transmittance of plastic greenhouse films. The LS116 transmittance meter conforms to the CIE photopic luminosity function Standard. The transmittance meter has passed the inspection of Chinese Metrology and Quality Inspection Institute and obtained the testing certificate.
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