With the power of the UVC lamp to enhance and technical refinement, in the market has been lent by the safety, environmental protection, compact and other performance, and no chemical residues and other advantages gradually replaced the lower power of the UV mercury lamps. This paper summarizes the far UVC lamp test found that the lamp bead lamp type, wavelength, luminous efficiency, irradiation distance, irradiation time, radiation intensity, penetration rate, application areas, and other factors that affect the disinfection and sterilization of far UVC lamps.

In this paper, we cite three experiments to illustrate the importance of several of these factors and recommend that customers scientifically design experimental conditions to evaluate the germicidal effect of far UVC lamps depending on product performance and application areas

Let’s dive right in now, and you can click on the question that interest you, 

NumberStrain nameLamp bead currentIllumination dataIllumination timeIllumination intensity(μW/cm²)Post-test colony count (CFU/mL)Germicidal rate (%)
Case 1:UVC luminaireCandida albicans1.0A1.0 m15 min983.2*10⁴90.99
Staphylococcus aureus1.0A1.0 m15 min985.0*10¹>99.99
Escherichia coli1.0A1.0 m15 min982.4*10²97.07
Case 2:UVC luminaireEscherichia coli350mA5 cm30 s/7.5*10²98.44
Escherichia coli350mA5 cm40 s/1.4*10²99.71
Escherichia coli350mA5 cm50 s/<1>99.99
Case 3:UVC luminaireStaphylococcus aureus300mA5 cm60 s/<1>99.99
Staphylococcus aureus300mA7 cm60 s/8*10²94.66
Staphylococcus aureus300mA10 cm60 s/4*10³46.66

1 Comparison of the germicidal effect of the same far UVC lamp on different strains of bacteria

The far UVC lamp with a central wavelength of 275 nm was selected, and its radiation intensity was 98 μW/cm² at an irradiation distance of 1 m. The sterilization effect of Candida albicans, Staphylococcus aureus, and Escherichia coli was evaluated by comparing the blank group after 15 min of vertical irradiation. The test results in this experiment showed that the same kind of UVC lamp, although the radiation intensity is the same, the sterilization effect of different strains of bacteria are different.

 Strain nameLamp bead currentIllumination dataIllumination timeIllumination intensity(μW/cm²)Post-test colony count (CFU/mL)Germicidal rate (%)
Candida albicans1.0A1.0 m15 min 3.5*10⁵ 3.2*10⁴90.99
Staphylococcus aureus1.0A1.0 m15 min 3.35*10⁵5.0*10¹>99.99
Escherichia coli1.0A1.0 m15 min8.2*10⁵2.4*10²97.07

UV lamp

UV lamp

UV lamp

2 Comparison of the sterilization effect of the same far UVC lamp on the same strain of bacteria at different irradiation times

A far UVC lamp with a central wavelength of 280 nm was selected and its bactericidal effect on E. coli was evaluated after the 30s, 40s, and 50s of vertical irradiation from above the culture medium. This test shows that at the same irradiation distance, with the increase of irradiation time, the sterilization effect is significantly enhanced, far UVC lamp has a better sterilization effect on E. coli after 50s irradiation. The testing effect is shown as follows.

 Strain nameLamp bead currentIllumination dataIllumination timePost-test colony count (CFU/mL)Germicidal rate (%)
Escherichia coliNo irradiationNo irradiation 4.8*10⁴
Escherichia coli350mA5 cm30 s 7.5*10²98.44
Escherichia coli350mA5 cm40 s 1.4*10²99.71
Escherichia coli350mA5 cm50 s<1>99.99

uv lamp

UV lamp 4

3 Comparison of the sterilization effect of the same far UVC lamp on the same strain at different irradiation distances

A far UVC lamp with a central wavelength of 275 nm was selected. The sterilization effect of the lamp on Staphylococcus aureus was evaluated after irradiation for the 60s at a distance of 5 cm, 7 cm, and 10 cm vertically above the culture medium. In this test far UVC lamp in the same irradiation time, with the increase of distance, the sterilization effect is significantly reduced; at a distance of 5 cm has a better sterilization effect on Staphylococcus aureus. The test results are shown below.

 Strain nameLamp bead currentIllumination dataIllumination timePost-test colony count (CFU/mL)Germicidal rate (%)
S. aureusNo irradiationNo irradiation1.5*10⁴
S. aureus300mA5 cm60 s<1>99.99
S. aureus300mA7 cm60 s8*10²94.66
S. aureus300mA10 cm60 s4*10³46.66

uv lamp

UV lamp2

For traditional UVC lamps, this paper argues that the following differences need to be considered in designing far UVC germicidal experiments:

  1. Wavelength: Different wavelengths of UVC for bacteria, viruses kill different effects. Traditionally used ultraviolet mercury lamps to discharge to produce a wavelength of 253.7 nm-based ultraviolet radiation, but according to the latest research findings, near 264 nm, the germicidal effect of UV may be higher. In far UVC lamp germicidal disinfection, standardization faces a series of challenges, such as UVC mercury lamp germicidal mainly in 253.7 nm, while far UVC lamp wavelengths are mainly distributed in 200-280 nm, which brings a series of differences for subsequent application solutions.
  2. UVC dose: germicidal requires sufficient irradiation intensity, sufficient time, and the appropriate wavelength band. UV radiation intensity depends on the luminous intensity of the effective spectrum in the UV light source, the light output angle of the lamp (beam concentration), the distance between the lamp and the object being radiated, and other factors. Generally speaking, the higher the radiation intensity, the better the effect; the more concentrated the beam is on the surface of the object being radiated, the better the sterilization effect; the closer the object being radiated, the better the effect; the longer the cumulative radiation time that the object being radiated under the UV lamps, the better the effect.
  3. Luminous efficiency: currently, far UV lamps in luminous efficiency and other aspects can not completely replace mercury lamps. UVA LED technology has been more mature. UVB and UVC band far-ultraviolet LED external quantum efficiency is still relatively low, EQE is mostly below 10%, commercial products are basically in the 1% to 3%.
  4. Application areas: far-ultraviolet lamps also have the advantages of being small and portable, environmentally safe, easy to design, etc., which can give rise to a number of differences from the traditional mercury lamp. It can give rise to a number of differences from the traditional mercury lamp application needs. For example, portable electronic disinfection products, elevator handrail sterilization machines, sweeping robots, etc. have emerged. This is where traditional UV light sources are difficult to apply.
  5. Ultraviolet penetration: far-ultraviolet light has a good inactivation effect on the surface of directly irradiated objects, but penetration is not strong, there is no significant effect on the inside of the object that the light does not penetrate and the part that is covered, while traditional ultraviolet lamps can use the dispersion of the ozone produced to make up for the shortcomings of disinfection due to ultraviolet light only spread along a straight line, there are dead ends.
  6. Germicidal differences: different brands, different specifications of UV lamps germicidal variability, the purchase to confirm its light source radiation wavelength, radiation intensity, protection design, work requirements, etc., choose the right lamps.

UAP002 Air Purifier

UV lamp

UDA003 UVC Bag


UAP003 Air Purifier

Air Purifier

UDX004 UVC Box


4 Introduction to the depth of far UVC lamp

1) Far UVC lamp sterilization advantages

1. High-efficiency sterilization: sterilization and inactivation of bacteria and germs is generally completed within seconds and occurs almost instantaneously.

2. Broad-spectrum sterilization: almost all bacteria and viruses can be killed with high efficiency.

3. No secondary pollution: no other chemical pollutants produced.

The germicidal efficiency of far UV light for common bacteria and viruses is shown in the following table.

Far UV radiation intensity: 90μW/cm²

CategoryName100% sterilization time  (s)CategoryName100% sterilization time (s)
BacteriaBacillus anthracis0.3BacteriaMycobacterium tuberculosis (branch)0.41
Bacillus diphtheriae0.25Vibrio cholerae0.64
Bacillus tetanus0.33Pseudomonas spp.0.37
Clostridium botulinum0.8Salmonella spp.0.51
Bacillus dysenteriae0.15Intestinal fever bacteria0.41
Escherichia coli0.36S. typhimurium0.53
Leptospira0.2Shigella spp.0.28
Legionella pneumophila spp.0.2Staphylococcus spp.1.23
Micrococcus spp.0.4~1.53Streptococcus spp.0.45
PathogensAdenovirus0.1PathogensInfluenza virus0.23
Bacteriophage virus0.2Mycoplasma virus0.8
Echovirus0.73Tobacco mosaic virus16
Echovirus type I0.75Hepatitis B virus0.73
Mold sporesAspergillus niger6.67Mold sporesOospores0.33
Aspergillus0.73~8.80Penicillium spp.0.87~2.93
fecal fungi8Penicillium toxigenicum2.0~3.33
Trichoderma spp.0.23~4.67Penicillium other fungi0.87
AlgaeBlue-green algae10~40AlgaeCryptococcus spp.7.3
Chlorella spp.0.93Green algae1.22
Nematode eggs3.4Protozoa spp.4~6.70
Fish diseasesFungl1.6Fish diseasesInfectious pancreatic necrotizing disease4
Leukoplakia2.67Viral hemorrhagic disease1.6

2) UV band classification

According to UV wavelength classification.

UVA: 315-400 nm (near-ultraviolet NUV365-400nm), applications include curing, photocatalytic purification, anti-counterfeiting, and other fields.

UVB: 280-315 nm, applications include light health / medical, plant growth light regulation, etc.

UVC: 200-280 nm (solar blind – “day blind” ultraviolet), used in applications such as water, air sterilization

3) Ultraviolet disinfection principle

UV disinfection technology is based on the research basis of modern epidemiology, medicine, and photodynamics, and is realized by using specially designed high-efficiency, high-intensity, and long-life UVC-band UV lamps. UV radiation damages and destroys the function of nucleic acids through the radiation of microorganisms (bacteria, viruses, bacteriophages, and other pathogens), thus killing the microorganisms and achieving the purpose of disinfection and sterilization, and the inactivation effect depends on the UV radiation dose.