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Sodium Vapour Lamp consists of a discharge tube produced 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 develop adequate heat to vaporize the sodium. Simply because of law pressure inside the tube, a sufficiently extended tube essential to obtain more light. To decrease the general dimension of the lamp, this tube is usually bent into U-shape.<br><br>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 essential to preserve this temperature. For this goal the U-tube is enclosed in a double walled flask to stop lose of heat. The double walled flask is interchangeable and can be fitted on to an additional U-tube. Whilst replacing the inner U-tube [http://www.chickencoopselect.com/chicken-houses analyze chicken houses] a single have to be very careful simply because if it is broken and sodium comes in get in touch with with moisture, it may outcome in fire.<br><br>All electric discharge lamps need a higher voltage at the time of starting and low voltage throughout operation. Generally, 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 start off the discharge. When the lamp is completely operative after ten - 15 minutes, [http://www.chickencoopselect.com/ chickens coops discussions] the voltage across it falls to about 150 volts. Simply because of the high reactance of circuit, the power issue is low and hence a p.f improvement capacitor is connected.<br><br>The efficiency of a low pressure sodium vapour lamp is very high (about 40 - 50 lumens/watt) and it produces a [http://www.chickencoopselect.com/ rate us online] light of particular wavelength getting yellow color. Sodium lamps are mainly employed for street, high way and airfield lighting exactly where color distinction is not so essential.