Sodium Vapour Lamp

Sodium Vapour Lamp consists of a discharge tube made from a heat resistant glass, containing a small amount of metallic sodium, neon gas and two electrodes, Neon gas is added to start the discharge and to develop enough heat to vaporize the sodium. Because of law pressure inside the tube, a sufficiently long tube required to obtain more light. To reduce the overall 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 0.004mm of mercury. This pressure is obtained at a temperature of about 280 C and so it becomes necessary to maintain this temperature. For this purpose the U-tube is enclosed in a double walled flask to prevent lose of heat. The double walled flask is interchangeable and can be fitted on to another U-tube. While replacing the inner U-tube one must be very careful because if it is broken and sodium comes in contact with moisture, it may result in fire. All electric discharge lamps require a higher voltage at the time of starting and low voltage during 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 sufficient to start the discharge. When the lamp is fully operative after 10 - 15 minutes, the voltage across it falls to about 150 volts. Because of the high reactance of circuit, the power factor is low and hence a p.f improvement capacitor is connected. The efficiency of a low pressure sodium vapour lamp is very 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 where color distinction is not so necessary.

5 Quick Gardening Tips to Save You Money

It's easy to spend a fortune every year creating a beautiful yard. These five tips can help save you money in both this, and future gardening seasons.

1.) Plan your vegetable garden according to what your neighbors are planting so you can share your vegetables when they're ready for eating.

2.) Select perennials rather than annuals for your flowerbeds. As they multiply each year, cut them back and exchange with your friends so you both have lovely gardens and save money at the same time.

3.) Compost your kitchen scraps, as well as your coffee grounds. The end result is much better than any potting soil you can ever get buy from a nursery or hardware store. The price is right, and this is definitely recycling!

4.) Instead of using mulch, try pebbles or small rocks in your garden as ground cover. This will save you lots of cash since you won't need to buy mulch in the spring and fall of every year.

5.) Spend more money now by purchasing better quality gardening tools and you will save in the long run. They will last for years, saving you dollars because you don't need to replace them every planting season. The same goes for gardening gloves- make sure you buy the best you can afford so they last all season.