Sodium Vapour Lamp

Sodium Vapour Lamp consists of a discharge tube created from a heat resistant glass, containing chickencoop discussion a tiny amount of metallic sodium, neon gas and two electrodes, Neon gas is added to start the discharge and to create sufficient heat to vaporize the sodium. Because of law pressure inside the tube, a sufficiently lengthy tube essential to acquire far more light. To decrease the general dimension of the lamp, this tube is generally bent into U-shape.

The light produced by this lamp is yellowish which is produced at its optimum pressure of about .004mm of mercury. This pressure is obtained at a temperature of about 280 C and so it becomes required to maintain this temperature. For this purpose the U-tube is enclosed in a double walled flask to avoid lose of heat. The double walled flask is interchangeable and can be fitted on to an additional U-tube. While replacing the inner U-tube 1 should be extremely careful since if it is broken and sodium comes in contact with moisture, it could result in fire.

All electric discharge lamps need a greater voltage at the time of beginning and low voltage in the course of operation. Usually, sodium vapour lamps are operated by a high leakage reactance transformer. At starting a high voltage of about 450 volts is applied across the lamp which is enough to begin the discharge. When price s chicken coop article the lamp is fully operative right after ten - 15 minutes, the voltage across it falls to chicken pen about 150 volts. Because of the high reactance of circuit, the power element is low and hence a p.f improvement capacitor is connected.

The efficiency of a low pressure sodium vapour lamp is quite high (about 40 - 50 lumens/watt) and it produces a light of specific wavelength possessing yellow color. Sodium lamps are mostly employed for street, high way and airfield lighting where color distinction is not so needed.