Sodium lamps are the most efficient group of visible radiation sources. They are characterized by high light transmission and a slight decrease in luminous flux during prolonged use.
Often, sodium lamps are used for economical illumination of external objects - streets and construction sites, highways and tunnels, architectural structures, railway stations and airports, and other objects that require contrast visibility in all weather conditions. In addition, such lamps are widely used for lighting flower beds and greenhouses with plants.
Arc sodium tube lamp (HSS) is a glass container containing a special "burner" - a cylindrical tube with pure aluminum oxide. This tube is filled with sodium and mercury vapor. In addition, these lamps contain xenon starting gas.
There are two types of them - high pressure sodium lamps, which allow you to receive monochrome light orange radiation, and low pressure, which provide about 200lm / W, but are characterized by a warm color range.
It should be noted that sodium lamps are connected in a special way - usinga special ballast and an impulse-inflammatory device, although some manufacturers produce such lamps with a starting antenna, which looks like a wire that wraps around the “burner”.
If we talk about the advantages of sodium lamps, the following characteristics should be noted:
• high light output;
• long service life (up to 32 thousand hours);
• slight change in luminous flux during operation;
• economical use;
• operating temperature range, which is -60 - +40 ° С.
Despite the listed advantages, sodium lamps have certain disadvantages:
• can only be used when there are no high requirements for good color rendering. In addition, when working for a long time, they change their color range;
• The efficiency of these lamps depends on the ambient temperature - in cold weather they shine worse;
• are not ecological as they contain sodium compounds with mercury;
• they are only recommended for minor fluctuations in the supply voltage;
• Sodium atoms leak during operation, requiring the use of a single crystal discharge tube;
• It takes at least 7 minutes to fully start this type of lamp and establish stable light characteristics.
Given such features of sodium lamps, theirit is better to use in cases where a powerful and economical light source is required, and the correct color reproduction is not very important.
It is worth noting that the power of these lamps should be selected in accordance with their use. So, for artificial lighting of flower beds, greenhouses or nurseries for plants, it is best to use lamps of 150 or 250 watts. Sodium lamps for plants with a power of more than 400 W are not used, as they can burn the leaves. With the correct application of this light source, you can improve the growth of plants and grow them intensively throughout the year.
