Hydrargyrum quartz iodide (HQI) is a trademark name of

Osram Osram Licht AG is a German company that makes electric lights, headquartered in Munich and Premstätten (Austria). Osram positions itself as a high-tech photonics company that is increasingly focusing on sensor technology, visualization and t ...

's brand of metal halide lamps made for general floodlighting, arena floodlighting, shop and commercial and industrial lighting. ''Hydrargyrum'' is the

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

name for the element mercury. When heated, mercury vapour is created inside the lamp, and deposited when it cools. An HQI lamp consists of a protective outer glass shield surrounding two heavy wires which are inserted into each end of a smaller inner bulb containing a gas. The lamp is powered by an

electrical ballast An electrical ballast is a device placed in series with a load to limit the amount of current in an electrical circuit. A familiar and widely used example is the inductive ballast used in fluorescent lamps to limit the current through the tub ...

, which regulates the current flow through the arc in the smaller inner lamp. Like all HID lamps, HQI lamps operate under high

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country a ...

and

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

, and require special

light fixture A light fixture (US English), light fitting (UK English), or luminaire is an electrical device containing an electric lamp that provides illumination. All light fixtures have a fixture body and one or more lamps. The lamps may be in sockets for ...

s for safe use. HQI lamps can produce different

color temperature Color temperature is the color of light emitted by an idealized opaque, non-reflective body at a particular temperature measured in kelvins. The color temperature scale is used to categorize the color of light emitted by other light sources ...

s when manufactured with different metal

halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a flu ...

s. They are relatively efficient light sources producing a high lumen per watt ratio (approximately 6x that of incandescent lamps). Like HMI, HQI lamps are a subset (or type) of

metal halide Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded. A few metal halides are discrete molecules, such as uranium hexafluoride, but most adopt polymeric structures, ...

lamps, which in turn are a subset of high-intensity discharge (HID) lamps. They should not be confused with quartz halogen lamps, which are a specialized type of

incandescent lamp An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxida ...

References

External links

Gas discharge lamps Metal halides {{Tech-stub fi:Monimetallilamppu