High-intensity discharge lighting

The first step in the design of a lighting system is the determination of the various lighting levels required for the specific areas of the facility. Typically, the majority of the fixtures are high intensity discharge (HID) fixtures and fluorescent fixtures. Certain applications may require incandescent fixtures as well. 

Mercury Vapor Lamp- A high-intensity discharge lamp that uses mercury as the primary light-producing element. Includes clear, phosphor coated, and self-ballasted lamps. 

Sodium Lights - A type of high intensity discharge light that has the most lumens per watt of any light source. 

Transparent ITR formulations are also used in refractors for high-intensity-discharge (HID) lamps. The refractors have to be able to withstand the combination of intense light (UV and visible) and heat. In addition, for many applications, such as vandal-resistant refractors, high impact strength is also required. The improved color stability of low- and medium-ITR resins over standard PC and UV-stabilized PC homopolymer is shown in tests with a sample surface temperature of 105 3°C and a 400-W metal-halide lamp (Fig. 14.21). 

Power factor meters are available for measurement of a given load. It is usually less expensive in the long run, however, to hire a local electrical contractor to conduct a PF survey and recommend correction methods. Possible sources of PF problems include transmitters, blowers, air conditioners, heating equipment, and fluorescent and high-intensity discharge lighting-fixture ballasts. 

Although most polymers are resistant to corrosion in indoor applications, radiation from indoor fluorescent lighting can cause yellowing in many plastics. Applications exposed to other types of artificial radiation, such as from high-intensity discharge lamps of gamma sterilization, can also subject various polymers to degradation. Prior to use the suitability of a particular resin should be checked. 

In modern cars, high-intensity discharge (HID) lighting is used more and more. 

Mercury. While mercury lamps used to be the standard in high-intensity discharge lighting, their time has passed. This technology has too many drawbacks low LPW, low CRI, poor lumen maintenance, and a blue light that has questionable appeal. In the next 5 to 10 yr, expect sales of mercury lamps to virtually evaporate. 

Photoreactors are simple in design, consisting of one or more high-intensity discharge lamps with a PTFE KOT tube reactor woimd aroimd one of the lamps. The PTFE tube creates a light-tube effect, which... 

Figure 28.1 Evolution in the luminous efficacy of distinct light sources. The curves of incandescent, halogen, high-intensity discharge (HID) (including mercury vapor, metal halide, and sodium vapor lamps), and fluorescent lamps are adapted from Ref. [8]. The LED curve is built based on data reported by Kovac et al. [16] and Farinola and Ragni [13] and the...

By increasing the lamp s internal operating pressures and temperatures, high-intensity light can be produced. High-intensity discharge lamps are classified as mercury-vapour, metal-halide, or high-... 

There are countless other reactions, many like these and others rather different, but the idea in every case is the same. A sudden flash of light causes an immediate photo-excitation chemical events ensue thereafter. This technique of flash photolysis was invented and applied to certain gas-phase reactions by G. Porter and R. G. W. Nor-rish, who shared with Eigen the 1967 Nobel Prize in Chemistry. High-intensity flash lamps fired by a capacitor discharge were once the method of choice for fast photochemical excitation. Lasers, which are in general much faster, have nowadays largely supplanted flash lamps. Moreover, the laser light is monochromatic so that only the desired absorption band of the parent compound will be irradiated. 

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