Halogen lamp

These gases create a chemical reaction cycle: the combination of Iodine and evaporating tungsten produces iodur vonfram, which does not deposit on the bulb as a conventional light bulb but instead, is brought back to the high temperature region around the filament (above 1,450 0C) by the convection movement then dissociates into two parts: tungsten redeposits back to the filament and halogen atoms are freed into gas. This recycling process not only prevents the color change but also enables filament to operate stable in a long time. Halogen bulb is designed to work at the temperature of above 250°C permitting halogen gas to evaporate. Quartz glass is mostly used to make halogen bulb since it can function at higher temperature and pressure (around 5 – 7 bar) compared to normal glass, resulting in higher luminous efficacy and extending the life of the lamp. Luminous efficacy of a Halogen lamp ranges from 20 – 27lm/W with the average life of 2,000 hours. Similar to the principle of normal incandescent lamps, Halogen lamp has the color rendering index (CRI) of nearly 100. This is a recommended lamp for high quality luminosity demands such as uses in galleries, museums, and meeting rooms or to perform tasks which require meticulousness and identification of colors and details. Another advantage of Halogen lamp is its design of one single filament and a smaller envelope, which allows adjusting the focus more accurately in comparison with ordinary lamps.

The principle of Halogen lamp is also applicable to Halogen heater. It is designed based on the principle to use durable heat light, which produces heat fast and broadly, without burning oxygen, thus, users are free from the worry of oxygen insufficiency. Halogen heater is also an energy saving method ideal for winter heating demand with portable and wall-mounted structure.

Fluorescent lamp

Fluorescent lamp consists of two main components, one glass tube and two electrodes at the two ends. The tube is vacuum-evacuated and added inside with a small bit mercury and inert gas, normally argon or neon. The interior of the tube is coated with fluoresce or phosphor powder. The tube has two electrodes, one at each end, which are wired to an electrical circuit. When the lamp is turned on, an electric arc, ie. discharge pulse in inert gas to produce visible light, is created. Specifically, when the electricity is supplied and establishes a high voltage between the electrodes, the two filaments glow and emit electrons traveling inside the tube from this electrode to the other at high speed. On the way, they collide with inert gas atoms leading to the emission of further ions. When electrons and ions are traveling inside the tube, they interact with mercury gas atoms. These collisions enable mercury gas atoms to release ultraviolet light photon or invisible ultraviolet rays. However, when ultraviolet rays hit the interior of the lamp, phosphor atoms release infrared photon with visible white light, which generates little heat. Producers can change light colors by using different fluorescent compounds.

Fluorescent lamp has cold light, high luminous efficacy, high color rendering index (CRI = 65 -90) and high life span (8000 – 12000 hours), which is the most ideal for interior use such as shops, offices, living rooms and etc. This lamp can be made with different length such as 0.3m, 0.6m, 1.2m, 1.5m, and 2.4m.
Luminous efficacy of fluorescent lamp depends much on tube diameter. When tube diameter increases, luminous efficacy decreases because several radiations 253.7nm are retained. At present, the prevailing types of fluorescent lamp in the market are T10, T8 and most recently, T5. Accordingly, T stands for Tube, the next number indicates the tube diameter of 1/8 inch (British unit of measure equal to 254mm). T10’s tube diameter is 10/8 inch = 32mm, similarly, T8’s is 26mm. T5’s is 16mm. With the same luminous efficacy and smaller tube, T5’s power is only 28W, much lower than T10 with 40W. In spite of its high price, T5 fluorescent bulb has significant energy saving capacity compared to T10 bulb with old technology applied. In order to change into new technology, T5 light bulb is designed to be easily replaced old T10 light bulb.

Some tips to extend fluorescent lamp life and enhance luminous efficacy:

Fluorescent lamps are sensitive to ambient temperature. Peak efficacy is attained with an ambient temperature of around 25°C. When the temperature is lowered to 0 0C, its efficacy is reduced to only 70%
Luminous flux loss of fluorescent lamps during its operation depends on voltage and grid electricity frequency. Thus, fluorescent lamps should operate in an environment with stable electricity supply. In some cases, low voltage fails to maintain discharge pulse so the lamp is turned off.
Life span and operational efficiency of fluorescent lamps heavily depend on associated equipments. The replacement of ferromagnetic ballasts and starters with electronic ballasts can reduce electricity consumption and light is radiated immediately when turned on. Reflective lamp shape or similar device could help provide sufficient and comfortable light.