Types of HID Bulbs

A high intensity discharge (HID) light bulb uses specific gases to produce the light seen in the bulb. Depending upon the gas used, the bulb may be very white or more blue on the spectrum. The bulb holds the gas within a vacuum of pressure inside the glass structure. HID bulbs vary in size and wattage, and are used for homes and cars alike.

Mercury Vapor

This high intensity vapor bulb contains mercury vapor inside the glass bulb. When electricity is sent to the bulb, the vapor is heated until it reaches a point where light is emitted. With mercury, the bulb may display as bluish, rather than pure white or yellow (like some popular incandescent bulbs do.) Mercury vapor bulbs are often used in homes as an energy-saving alternative to incandescents, although compact fluorescent light (CFLs) have begun to replace mercury vapor HIDs.

Metal Halide

Metal halide bulbs contain a mixture of metals, including thallium and sodium, along with mercury vapor. The metals are mixed to provide one of the better color-lecting bulbs (meaning it shows true colors, rather than emitting a hue) as described by Greenbuildingadvisor.com. Metal halide bulbs are favored as a replacement to other forms of HID bulbs because of this quality, and because they do not need excessive time to warm up and illuminate.

Pressurized Sodium

Pressurized sodium bulbs produce light by heating xenon gas until a combination of sodium and mercury cause sodium electrons to release and glow. High-pressure sodium (HPS) bulbs are the yellow glowing lights used along many major roads and throughout cities. With 10 times more lumens than an incandescent bulb, pressurized sodium bulbs are much brighter and can reach greater distances. Low-pressure sodium lights are used primarily by astronomers, since the intense orange light emitted can be filtered for space observation.