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Sodium Vapour Lamp consists of a discharge tube created from a heat resistant glass, containing a modest amount of metallic sodium, neon gas and two electrodes, Neon gas is added to begin the discharge and to create adequate heat to vaporize the sodium. Due to the fact of law pressure inside the tube, a sufficiently long tube essential to obtain more light. To minimize the overall dimension of the lamp, this tube is usually bent into U-shape.

The light developed by this lamp is yellowish which is made at its optimum pressure of about .004mm of mercury. This pressure is obtained at a temperature of about 280 C and so it becomes essential to keep this temperature. For this objective the U-tube is enclosed in a double walled flask to avert lose of heat. The double walled flask is interchangeable and can be fitted on to another U-tube. Although replacing the inner U-tube a single should be quite careful simply because if it is broken and sodium comes in get in touch with with moisture, it may possibly outcome in fire.

All electric discharge lamps demand a greater voltage at the time of starting and low voltage for the duration of operation. Usually, sodium vapour lamps are operated by a high leakage reactance transformer. At beginning a high voltage of about 450 volts is applied across the lamp which is enough to start the discharge. When the lamp is completely operative following 10 - 15 minutes, the voltage across it falls to about 150 volts. Due to the fact of the high reactance of circuit, the power element is low and therefore a p.f improvement capacitor is connected.

The efficiency of a low pressure sodium vapour lamp is extremely high (about 40 - 50 lumens/watt) and it produces a light of particular wavelength having yellow color. Sodium lamps are mainly employed for street, high way and airfield lighting exactly where color distinction is not so essential. like here's the site e cigarette brands