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Do I Need a Germicidal Lamp or Germicidal Bulb?

Posted by Doug Root on October 01, 2015

Easy question...the answer is they are the same thing. Bulb and lamp is used synonymously in the lighting industry!

A germicidal lamp is a special type of lamp which produces ultraviolet light (UVC). This short-wave ultraviolet light inerupts DNA base pairing which in turn causes thymine-thymine dimers. This then leads to death of bacteria on exposed surfaces. In air cleaning applications, ozone production is an unwanted by product. However for water purification you will need to use an ozone producing lamp(NM under 253.7).

Low-Pressure Germicidal Lamps

The low-pressure germicidal lamps look just like a standard fluorescent lamp, however they are clear. They have a wavelength of 253.7 nm. Germicidal lamps are used to sterilize tools, surfaces and air in medical facilities and commercial buildings. most popular germicidal lamps are the clear low pressure type from names like PHILIPSLight Emissions TechnologyUSHIOOSRAM. They are clear because they have no fluorescent phosphor coating on the inside of the lamp. These lamps are also made of a different type glass. Most fluorescent tubes are made of standard borosilicate glass however germicidal bulbs are made with a special fused quartz glass. With the glass and no phosphor coating, the 253.7 nm ultraviolet light produced by the mercury arc is passed outside the lamp and used for sterilization rather than general light. 

Germicidal lamps are very common now in sterilization applications. OEM's use these lamps in HVAC equipment, water purification and surface sterilization. You will see that in many of the part numbers they carry the "OF" label which means that the lamp is Ozone Free.

These lamps are extremely dangerous when viewed by the naked eye or exposed skin. Short-wave UV light is harmful.  It is imperative that these lamps be shielded from human contact. OSRAM Sylvania PURITEC HNS lamps carry these warnings: PURITEC HNS germicidal lamps emit high-intensity UV radiation that can cause sunburn and conjunctivitis. The skin and eyes must therefore not be exposed to direct or reflected unfiltered radiation.

The 2 types of germicidal lamps you will find are linear tubes and compact plug in type.


Germcidal bulbs

Our most common lamps are listed below, we see these in 75% of applications, these lamps are ozone free:


Mid Range Germicidal Lamps

Mid range germicidal bulbs are not clear like their low pressure counterparts. These lamps produce a 287 nm wavelength and have a special phosphor coating on the inside of the lamp. These lamps produce UV-B light. USHIO produces a few versions of these specialty germicidal bulbs. G6T5/EG8T5/E G15T8/EG25T8/E.

If you are looking to replace your germicidal lamp in an OEM's so with caution. Please make sure the unit is off and you do not look directly at the light. Remove the germicidal lamp and get the part number off the lamp. This will help team find the replacement lamp. The rest is simple, go to and type your germicidal lamp number into the search box! 

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