Sodium Vapour Lamp

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 start the discharge and to create sufficient heat hen houses for sale chat to vaporize the sodium. Since of law pressure inside the tube, a sufficiently long tube essential to acquire a lot more light. To reduce the overall dimension of the lamp, this tube is typically bent into U-shape.

The light created by details 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 success becomes necessary to sustain 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 one more U-tube. While replacing the inner U-tube 1 must be extremely careful due to the fact if it is broken and sodium comes in make contact with with moisture, it could outcome in fire.

All electric discharge lamps call for a larger voltage at the time of starting and low voltage in the course of operation. Normally, 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 sufficient to start the discharge. When the lamp is fully operative right after 10 - 15 minutes, the voltage across it falls to about 150 volts. Due to the fact of the high reactance of circuit, the power aspect is low and hence a p.f improvement capacitor is connected.

The efficiency of a low pressure sodium vapour lamp is really high (about 40 - 50 lumens/watt) and it produces a light of certain wavelength having yellow color. Sodium lamps are mainly employed for street, high way and airfield lighting exactly where color distinction is not so necessary.