Sodium lamps: main characteristics and scope

Sodium lamps are the most effective group of sources of visible radiation. They are characterized by high light transmission and a slight decrease in light fluxes during prolonged operation.

Often, sodium lamps are used for economical lighting of external objects - streets and construction sites, transport routes and tunnels, architectural structures, stations and airports, 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.

The arc sodium tube lamp (DNaT) is a glass cylinder 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 starting gas - xenon.

There are two types of them: high-pressure sodium lamps, which make it possible to obtain monochrome light orange light, as well as low pressure, which provide approximately 200 lm / W, but are characterized by a warm color range.

It should be noted that sodium lamps are connected in a special way - with a special ballast and a pulse-inflammatory device, although some manufacturers produce such lamps with a starting antenna that looks like a wire that wraps around the "burner".

If we talk about the advantages of sodium lamps, we should note the following characteristics:

• high luminous efficiency;

• long period of operation (up to 32 thousand hours);

• slight change in light output during operation;

• economy of use;

• Operating temperature range, which is -60 - +40 ° C.

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, with prolonged operation, they change their color range;

• The effectiveness of these lamps depends on the ambient temperature - in cold weather they shine worse;

• are not ecological, since they contain sodium compounds with mercury;

• they are recommended to be used only with minor fluctuations in the supply voltage;

• During operation, a leakage of sodium atoms takes place, which requires the use of a single-crystal discharge tube;

• It takes at least 7 minutes to fully start this type of lamps and establish stable light characteristics.

Given such features of sodium lamps, they are best used in cases where a powerful and economical light source is required, and the correct color rendition is not very important.

It should be noted that the power of these lamps should be selected in accordance with their use. So, for artificial illumination 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, since they are able to burn sheets. With the correct application of this light source, it is possible to improve the growth of plants and intensively grow them throughout the year.