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Incandescent Basics The basic design of the incandescent lamp has not changed much since the late 1800s, when Thomas Alva Edison successfully produced the first operati- onal electric light bulb. These are the must-know fundamental facts about incandescent lamps and the alternative choices that are available today . Halogen Basics Halogen light bulbs operate on the same principle as standard incandescents heating the tungsten filament until it glows but from there, halogens improve upon the process. Compact Fluorescent Basics Fluorescent lamps are phosphorous-coated tubes filled with a low-pressure mercury vapor. Light is produced by passing an electric arc between tungsten cathodes at opposite ends of the tube. This causes the mercury vapor to generate a radiant energy. The Glass Bulb The filament inside an incandescent lamp must be protected so that oxygen does not reach it and cause it to evaporate on contact. Most incandescent lamps are either vacuum-sealed or gas-filled. It was discovered in the early 1900s that the introduction of gas inside the bulb, or envelope, created a pressure against the filament. This pressure allowed the filament to burn hotter and last longer. Most gas-filled incandescent lamps today use a mixture of argon and nitrogen gases. The Filament Incandescent lamp filaments are made of tungsten. Tungsten is a metal that can operate at very high temperatures without evaporating too quickly and resulting in early lamp failure. Incandescent filaments only convert about 10 percent of the energy used into visible light, so it is necessary touse a material that can withstand extremely high emperatures. Most lamps use a coiled filament design, which has been stronger an deliver better performance. Key Characteristics Rated Voltage: The lamp’s filament is designed to operate within a specific voltage range in order for it to deliver its intended light output. Lamps that are burned at voltages higher than their rating will result in higher wattage, efficacy (lumens per watt) and lumens. Lamps operated below their rated voltage will significantly increase their life while reducing their wattage, efficacy and lumen output. Burning Position: For the most part, incandescent lamps can be burned in any position. However, take note and observe a lamp manufacturer’s recommendations for use. . How It Works: Operation of halogen lamps is based on the “Halogen Cycle” (see right). Tungsten particles from the bulb’s filament evaporate. The evaporated tungsten collides with the halogen gas. The particles ond with the halogen gas. Tungsten is then redeposited back to the filament and the gas is re-released. The operating temperature is a significant factor to ensure that the halogen cycle performs properly. The interior wall of the bulb must be above 250°C and less than 1,100°C. Additionally, the filament of the lamp must reach at least 2,000°C. To reach this temperature, the interior wall must be in close proximity to the tungsten filament. Big Benefits: Halogen lamps offer a combination of benefits that make them an appealing alternative to standard incandescents in many applications . Color Temp Warm Cool Daylight Kelvin Range 2700K 4100K 5000K Effect & Mood Warm & Friendly Clean& Organized Bright & Alert Application Homes & Restaurants Office & Hospitals Galleries & Jewelry Display Tri-Phosphor Coating This mixture converts ultraviolet light into visible light with superior color rendition and a high efficacy averaging 60 lumens per watt. Compact Fluorescent Tube An alternative to traditional linear tubes, these smaller-tubes have been configured into new shapes to reduce their size and increase their light output. Electronic Ballast These high-tech devices enable the lamp to light up immediately with no flickering or noise. Solid-state circuitry allows for three-way, dimmable and photocell models. • • • • • e v a p o r a t e . T u n g s t e n p a r t i c l e s f r o m t h e f i l a m e n t E v a p o r a t e d t u n g s t e n c o l l i d e s w i t h t h e h a l o g e n g a s . P a r t i c l e s c h e m i c a l l y b o n d w i t h t h e h a l o g e n g a s T u n g s t e n i s r e d e p o s i t e d b a c k i n t o t h e f i l a m e n t a n d t h e g a s i s r e l e a s e d . • U N D E R P R E S S U R E • U N D E R P R E S S U R E In order for the halogen cycle to function properly, the gas must be inserted into the quartz envelope at a very high level of pressure, and it must be sealed off and maintained at the same level. For safety reasons, a particle barrier is required.