Germicidal lamp

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A germicidal lamp (also known as disinfection lamp or sterilizer lamp) is an

(UVGI).

There are four common types available:

• Low-pressure mercury lamps
• High-pressure mercury lamps
• Excimer lamps
• LEDs

Low-pressure mercury lamps

Low-pressure mercury lamps are very similar to a fluorescent lamp, with a wavelength of 253.7 nm (1182.5 THz).

The most common form of germicidal lamp looks similar to an ordinary fluorescent lamp but the tube contains no fluorescent

). Germicidal lamps still produce a small amount of visible light due to other mercury radiation bands.

An older design looks like an

the incandescent filament.

As with all

ballast

to regulate the current flow. The older lamps that resembled an incandescent lamp were often operated in series with an ordinary 40 W incandescent "appliance" lamp; the incandescent lamp acted as the ballast for the germicidal lamp.

High-pressure mercury lamps

High-pressure lamps are much more similar to

HID lamps

than fluorescent lamps.

These lamps radiate a broad-band UVC radiation, rather than a single line. They are widely used in industrial water treatment, because they are very intense radiation sources. High-pressure lamps produce very bright bluish white light.

Excimer lamps

vacuum-ultraviolet

radiation at a variety of wavelengths depending on the medium. They are mercury-free and reach full output quicker than a mercury lamp, and generate less heat. Excimer emission at 207 and 222 nm appears to be safer than traditional 254 nm germicidal radiation, due to greatly reduced penetration of these wavelengths in human skin.

Light-emitting diodes (LEDs)

heatsink

and power cable

Recent developments in light-emitting diode (LED) technology have led to the commercial availability of UVC LED sources.

UVC LEDs use semiconductor materials to produce light in a solid-state device. The wavelength of emission is tuneable by adjusting the chemistry of the semiconductor material, giving a selectivity to the emission profile of the LED across, and beyond, the germicidal wavelength band. Advances in understanding and synthesis of the

materials system led to significant increases in the output power, device lifetime, and efficiency of UVC LEDs in the early 2010s.

The reduced size of LEDs opens up options for small reactor systems allowing point-of-use applications and integration into medical devices.^[2] Low power consumption of semiconductors introduce UV disinfection systems that utilized small solar cells in remote or Third World applications.^[2]

By 2019, LEDs made up 41.4% of UV light sales, up from 19.2% in 2014^[3] The UV-C LED global market is expected to rise from $223m in 2017 to US$991m in 2023.^[4]

Uses

Germicidal lamps are used to sterilize workspaces and tools used in biology laboratories and medical facilities. If the quartz envelope transmits shorter wavelengths, such as the 185 nm mercury emission line, they can also be used wherever

to remove as much visible light as possible, leaving just the UV light. Germicidal lamps are also used in waste water treatment in order to kill microorganisms.

The light produced by germicidal lamps is also used to erase

to tunnel through the gate insulation, eventually removing the stored charge that represents binary ones and zeroes.

Ozone production

For most purposes, ozone production would be a detrimental side effect of lamp operation. To prevent this, most germicidal lamps are treated to absorb the 185 nm mercury emission line (which is the longest wavelength of mercury light which will ionize oxygen).

In some cases (such as water sanitization), ozone production is precisely the point. This requires specialized lamps which do not have the surface treatment.

Safety concerns

Short-wave UV light is harmful to humans. In addition to causing

References

External links

• Media related to Germicidal lamps at Wikimedia Commons