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The plant energy necessary for growth and development is obtained from sunlight... But it is the sun that is lacking in winter for vegetables or flowers grown in greenhouses.
To compensate for this shortcoming, farmers are forced to use special lighting sources... Among them, sodium lamps have occupied a special niche.
Characteristics of sodium lamps for greenhouses
To date, no lamps have been created that could 100% create an imitation of sunlight. Each of them is dominated by only one emission spectrum.
As for seedlings, during the growing season, they especially need the blue and red spectrum. The first is needed for the growth and full development of seedlings, and the second, in turn, stimulates their flowering and subsequent fruiting.
For each period, respectively, the backlight needs its own.
Sodium sodium lamps for greenhouses belong to the category of gas-discharge lamps. Gas discharge devices are actively used not only in greenhouses, but also on squares, roads, streets, warehouses and industrial premises. The gas-discharge environment inside the devices is created using sodium vapor, glowing red-orange.
For comparison: in mercury, white glow prevails. As for the radiation itself, it is created by arc discharges. It is on them that the principle of operation of this kind of devices is based.
The lamp bulb is a cylindrical tube made of refractory glass. It is filled with a mixture of mercury and sodium. It contains a burner made of aluminum oxide.
Reference. Specialists, when designating such a lighting device, use the abbreviation DNaT, which means "sodium arc tube lamp". The main manufacturers of these products are two companies: Silvania and Philips.
To start such devices and regulate the action of the current in them, there is a ballast equipment. In addition, you will need a ballast electronic device with the following advantages:
- Thanks to its work, the power is stabilized, so the lamps last longer.
- Electricity consumption is reduced by almost 30%.
- The frequency of the current increases, the light output increases.
- There is no flickering effect.
Types of lighting fixtures
Sodium luminaires fall into two categories: high pressure and low pressure. In crop production, high pressure sodium lamps are used for greenhouses.
NLVD are divided into the following types:
- HPS Are conventional arc luminaires with powerful light emission. One of them is enough to illuminate a small vegetable garden construction.
The radiation spectrum of such devices can be changed by combining them with other types.
- DNaZ - light sources with a specular reflective layer. The layer is applied to the inner surface of the flask. It is effectively protected from adverse weather conditions and mechanical stress and increases productivity. Sintered electrodes are located inside the flask.
They provide high efficiency and reduce energy consumption... In comparison with HPS, mirror lamps are not powerful enough.
- DRI and DRIZ - the most advanced devices for greenhouses. Metal halide devices are resistant to current fluctuations, they serve for a long time, they have the most optimal spectrum radiation required for seedling growth, and high efficiency.
But they are not devoid of some drawbacks, of which the most important is the cost, which is quite high for an ordinary consumer. Plus, they require a special cartridge to use them. This makes it difficult to replace failed lamps.
The photo shows sodium lamps for greenhouses:
Features of NLVD
The luminous flux, luminous efficiency and duration of burning depend on the power of the NLVD. Color rendering is improved through the use of luminescent materials in conjunction with gas mixtures.
Concerning power, then it should be appropriate for the application. To illuminate the seedlings, devices with parameters of 70-400 W are selected, which can serve in greenhouses in any season of the year.
The higher reading bulbs will simply burn the vegetables. Therefore, before buying them, be sure to consult a specialist.
Advantages and disadvantages of high pressure sodium lamps
NLVD have many advantages:
- They are economical... They consume little electricity and are affordable.
- Durability: last about 20,000 hours.
- High luminous efficiency in comparison with simple incandescent lamps.
- Heat radiation... When the NLVD illuminates, a large amount of heat is generated. Therefore, you can save a lot on heating a greenhouse, especially during cold weather.
- The red-orange radiation spectrum allows accelerate flowering processes and fruit formation, which contributes to the appearance of a rich harvest. And the blue part, as a rule, provides natural light.
- High efficiency (thirty%). It exceeds that of most artificial lighting sources.
Attention! NLVD is best used in the last stages of seedling growth. If backlit is provided early, the shoots will grow faster, stretch out and form long stems. Proper growth can be achieved by combining the devices with metal halide lighting sources.
Disadvantages of NLVD
- The big minus of NLVD is strong heat, moreover, they flare up for at least a few minutes. Their lighting attracts pests to greenhouses, which cause significant damage to seedlings.
- NLVD are unsafe... A mixture of mercury and sodium acts as a filler. By accidentally breaking the lamp, you can put an end to the entire crop grown.
- Devices are voltage dependent... In the case when its fluctuations in the network exceed 10%, it is not recommended to use such lamps inside greenhouses.
- Into the cold lighting lose efficiency... Therefore, their use in unheated shelters is limited.
For reference! Plants in greenhouses where NLVD operate often look pale and unhealthy. But do not be afraid of this. This is an optical illusion. Sodium light simply distorts our color perception noticeably.
If you are used to growing vegetables, flowers and berries in a greenhouse all year round, sodium lamps will be an important tool for you when there is a shortage of natural light.
They are recognized as one of the most economical and at the same time effective methods of artificial lighting, allowing the gardener to get a rich harvest.
In the video below: a comparison of LED and sodium lamps for greenhouses