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The kinds of ultraviolet disinfection lamps and its application in disinfection

The kinds of ultraviolet disinfection lamps and its application in disinfection

2020-12-10

Ultraviolet disinfection lamps are used more and more, believe many friends have seen ultraviolet disinfection lamps, but do not know ultraviolet ray disinfection lamp to have what kind, ultraviolet disinfection lamp has what effect in disinfection. Below with Tepro ultraviolet disinfection lamps manufacturer see ultraviolet disinfection lamp common kind and action together.

ultraviolet disinfection lamps

Types of ultraviolet disinfection lamps

Various low-pressure mercury lamps producing pasteurized ultraviolet rays

Ultraviolet disinfection low-pressure mercury vapor discharge lamp shell made of quartz glass tube or through short wave uv glass tube, filled with low pressure inert gas and a little far, both ends of metal cold or hot filament electrode electrode, through to the poles and high pressure or after the trigger high-pressure start maintained by a lower supply voltage, discharge, resulting in a predominantly 253.7 nm ultraviolet light. This ultraviolet disinfection lamp sterilizes the action very strong, can destroy to the human body harmful bacterium or the virus, thus has the disinfection effect. The main varieties of low pressure mercury vapor discharge ultraviolet disinfection lamps are as follows:

1.1 Hot cathode low pressure mercury sterilizing ultraviolet disinfection lamps

The electrode of this discharge lamp is a double helix filament wound with tungsten wire, coated with a mixture of barium carbonate and strontium carbonate and calcium carbonate. When heated by electric current, the mixture is activated and decomposed to form oxides of calcium, strontium and barium. When the lamp is switched on, the filament is heated and emits electrons, bombarding the mercury vapor in the tube, causing electrons in the outer layer of the mercury atoms to jump to an excited state in a higher-energy orbital position. Electrons that jump to a higher energy orbital can stay only 10-5 to 10-11s, then fall back to a lower energy orbital, releasing energy in the form of ultraviolet light. The ultraviolet radiation of this lamp has a wavelength of over 95% of 253.7nm, while a small amount of wavelengths are 184.9nm, 404nm, 435nm, 545nm, 577nm and 579nm.

Low pressure mercury lamp discharge mercury vapor pressure of about 0.006Torr, generally used for uv transmittance of more than 80% of quartz glass tube. This lamp has the highest radiation intensity at 40°C.

Low-pressure mercury lamps include the following four types.

1.1.1 Straight tube UV sterilizing lamp

Straight tube ultraviolet sterilization lamp is the most classical structure, the length and diameter of the lamp can be calculated by formula. The radiation intensity of the 30W lamp shall be above 90 W/cm2 (at 1m), and shall not be less than 70 W/cm2 in use. The lamp's service life is 3000h, the power has 40W, 30W, 20W, 15W, 10W, 8W, 6W, 4W and so on several kinds.

1.1.2H hot-cathode low pressure mercury ultraviolet disinfection lamps

The 9W H-type hot-cathode low pressure mercury ultraviolet sterilizing lamp has a radiation intensity greater than or equal to 9000 W/cm2 at 3cm from the lamp tube. The radiation intensity of a 30W H lamp at 100cm from the lamp is greater than or equal to 200 W/cm2.

1.1.3 Low O3 UV lamp

Low O3 ultraviolet disinfection lamps can be made by either straight pipe lamp or H-type lamp. The method is to add 0.01% ~ 0.05% titanium oxide and 0.07% alumina in quartz glass, so that the ultraviolet disinfection lamps ray with wavelength less than 200nm is absorbed and O3 is produced very little.

1.1.4 High O3 ultraviolet disinfection lamps

This lamp not only produces a large amount of 253.7nm UV, but also radiates a strong 184.9nm UV, thus producing a large amount of O3. Due to the synergistic effect of O3 and UV, the disinfection effect is improved.

1.2 Cold cathode low pressure mercury ultraviolet sterilization lamp

An electrode made of nickel is filled with mercury and argon. By using a strong electric field, the cold cathode emits electrons, bombards mercury atoms, and causes them to emit light. The lamp can be made into various shapes, such as pan - shaped, U-shaped, straight tube, etc., more than 60% of the uv radiation wavelength is 253.7nm.

1.3 High pressure mercury ultraviolet sterilizing lamp

The pressure of mercury vapor in the lamp tube can reach several atmospheres, the power can reach 500 ~ 1000W or higher, in the radiation spectrum is only a small part of the sterilization of ultraviolet light, but the total energy is large, so still can be regarded as a good disinfection of ultraviolet light source, generally used for the disinfection of water.

Ordinary glass and plexiglass cannot transmit 253.7nm ultraviolet rays, but quartz glass can transmit more than 80%, and the transmittance of general plastics is very low. Polyfluoroethylene resin film (0.1mm thick) can penetrate about 60% of 253.7nm ultraviolet light, and ethylene copolymer film (0.1mm thick) can penetrate 40%. Uv rays, which can penetrate 2cm through water, are blocked by suspended particles as they travel through the air.

253. When 7nm ultraviolet disinfection lamp rays hit the surface of a material, they are generally absorbed and transformed into the internal energy of the material. It is difficult for them to penetrate into the deep part of the object.

The 253.7nm uv rays incident at the interface of the two media reflect and are refracting as they enter the second medium. The reflection coefficients of various materials to 253.7nm ultraviolet are different, and magnesium oxide is 80% ~ 93%. Polished aluminum 60% ~ 90%; White paint is 46%; White lime was 40% and white tile 4.7%. Can choose the reflection material of ultraviolet disinfection lamps accordingly.

2. Killing effect of ultraviolet disinfection lamps on microorganism

The band with the strongest bactericidal effect is about 254nm. Ultraviolet rays can kill a variety of microorganisms, including bacteria, fungi, viruses, rickettsia and so on. Each microbe has its own specific threshold for ultraviolet death dose. The sterilization dose K is the product of the irradiation intensity and the irradiation time. K=It

The same effect can be obtained by short time or long time irradiation with high intensity or low intensity when the intensity of uv light source is higher than 40 W/cm2. The lethal dose (W-S /Cm2) of uv to surface microorganisms was: Staphylococcus aureus, 2 180~4 950; Staphylococcus albicans, 3300~4 200; E. coli, 2 100~6 400; Pseudomonas aeruginosa, 6 500; Bacillus degeneres, 5, 500. The killing dose of ultraviolet radiation to microorganisms can be estimated by mathematical model (Y = killing rate, X= dose in the following equation) :

Bacillus cereus bud:

Lg (100-y) = 10.7142-2.407 8lgX;

Bacillus subtilis:

Lg (100-y) =9.101 3-2.054 31IgX;

E. coli:

Lg (100 -) Y = 7.4113-2. 16921 gx;

Staphylococcus albicans:

Lg (100-y) =10.366 2-2.739 1lgX.

For microorganisms in the water, the dose required to kill 99.9% of them is: Bacillus subtilis, 40,000; E. coli and Staphylococcus aureus, 12 000; Mycobacterium tuberculosis, 20 000; The flu virus, greater than 5,000.

Generally speaking, orchid negative bacteria are the most sensitive to ULTRAVIOLET ray, followed by gram-positive cocci. Bacterial spores and fungal spores are the most resistant. Viruses are also killed by ultraviolet light, and their resistance lies somewhere between a bacterial propagator and a bud.

There were bacillus subtilis, radiation-tolerant micrococcus and Orange yellow occidentalis in the patients with high resistance to UV. There were micrococcus, salmonella typhimurium, Streptococcus lactobacillus, saccharomyces and protozoa. Low resistance includes vaccinia virus, HIV, Escherichia coli, Staphylococcus aureus, Proteus vulgaris, Legionella, Brewer's yeast, and T3 Escherichia coli phages. ATCC 9372 strains of subtilis black variety have been used as ultraviolet disinfection indicator strains.

3. Factors affecting the effect of ultraviolet disinfection lamp

3.1 Influence of voltage

The radiation intensity of ultraviolet light source is obviously affected by voltage. When the voltage of the same ultraviolet light source is insufficient, the radiation intensity decreases greatly. Radiation intensity of 30W straight tube quartz ultraviolet disinfection lamps at different voltages.

The following formula can be used to calculate:

Y = 1.287-177.87 X

Where, Y -- theoretical value of ultraviolet intensity, unit W/cm2;

X -- voltage, unit :V.

If the intensity at 220V is 100 W/cm2 as the acceptance control point of the new lamp, then the control line for the radiation intensity of the new ultraviolet disinfection lamp measured at different voltages is

Y = 1.287-183.14 X

If the intensity at 220V is 70 W/cm2 as the control point for the replacement of the old lamp tube, the radiation intensity control line measured at different voltages is

Y = 1. 287 x - 213.14

3.2 Influence of distance

In general, the radiation intensity of an ultraviolet disinfection lamp is inversely proportional to the square of the distance. 30 w hot cathode straight torch radiation intensity of the low-pressure mercury Y ˆ decreased with increasing distance from tube x, the exponential relationship between the two.

Its exponential curve equation is

Y ˆ = 102.885? 9-0.760? 8x

According to this formula, the radiation intensity of ultraviolet disinfection lamp at different distances can be calculated.

3.3 Influence of temperature

The effect of temperature on ultraviolet disinfection is realized by influencing the radiation intensity of ultraviolet light source. In general, the germicidal UV radiation from uv light is strongest at 40°C. When the temperature drops, the output of the ultraviolet disinfection lamp decreases; When the temperature is higher than 42°C, the uv backabsorption of radiation increases and the output decreases. Accordingly, too high and too low temperature are disadvantageous to the disinfection of ultraviolet ray. However, some sterilization tests have proved that temperature has little effect on the sterilization effect of ULTRAVIOLET radiation in the range of 5 ~ 37°C. At low temperatures, microbes become more sensitive to ULTRAVIOLET light.

3.4 Influence of relative humidity

In the disinfection of air, relative humidity also has an effect on the disinfection effect. When RH is too high, the number of small water droplets in the air increases, which can block the ULTRAVIOLET rays. Therefore, when the air is required to be sterilized with ultraviolet rays, the relative humidity should be below 60%. If the surface is far away from the light source, the moisture particles in the air will also affect the disinfection effect.

3.5 Influence of exposure time

The disinfection effect of ULTRAVIOLET radiation has an exponential relationship with the irradiation dose, which can be expressed as

N/No=e-KIt

Where, N0 -- number of bacteria before irradiation;

N -- Number of bacteria after exposure for a certain time;

T -- Exposure time;

I -- Intensity of exposure;

K - constant.

As can be seen from the above formula, increasing the exposure time t or increasing the exposure intensity can increase the disinfection effect, and the exposure dose is the product of the exposure intensity | and the exposure time. Therefore, sufficient exposure dose must be ensured to achieve a certain degree of killing rate. Under the condition that the radiation intensity of ultraviolet light source reaches the requirement (greater than 40 W/cm2), the required irradiation dose can be achieved by adjusting the irradiation time.

3.6 Influence of organic matter protection

When microorganisms are protected by organic matter, it is necessary to increase the dose of irradiation, because organic matter can affect the penetration of ULTRAVIOLET light into microorganisms and absorb ultraviolet disinfection lamp.

3.7 Influence of microorganism species and quantity

Different microorganisms have different levels of resistance to ULTRAVIOLET light, so it is necessary to determine the irradiation dose according to the type of microorganisms killed. The more microorganisms are contaminated, the worse the disinfection effect will be. Therefore, it is necessary to have a good understanding of the types and quantities of the contaminated microorganisms on the objects to be disinfected before disinfection, so as to determine the irradiation dose.

Application of ULTRAVIOLET disinfection lamps in disinfection

4.1 The use scope of ultraviolet disinfection lamps

Ultraviolet disinfection lamps can kill measles virus, tuberculosis bacillus, influenza virus, adenovirus, poliomyelitis virus, coxac virus, staphylococcus, meningococcal, pneumococcus and so on all sorts of microorganism in the air. Using ultraviolet ray to disinfect air is a simple, convenient, cheap and reliable method.

Ultraviolet disinfection lamps can also be used to disinfect surfaces. At the same time, it also has a good bactericidal effect on the microorganisms in the water, no residual toxicity, after disinfection does not form harmful products, so it can be used for drinking water disinfection. The ultraviolet ray also has the good killing effect to the microorganism in the sewage, may use in the sewage disinfection.

Because ultraviolet disinfection lamps and lanterns has air disinfection, surface sterilization and disinfection of water function, therefore, it can be widely applied to hospitals in the public places and public goods, culture, entertainment, bath industry service units, hotels, restaurants, bar, teahouse, public and rental car, light rail and subway cars, airplanes and ships the cabin, shops and shopping places, community activities, schools, libraries and bookstores, public secondary water tank and water storage containers, swimming pool, banking and currency, childcare institutions, sports venues and public fitness equipment, beauty parlor, air-conditioning system etc., prevent the spread of germs in a public place or through public goods.

4.2 Various applications and precautions of ultraviolet disinfection lamps

4.2.1 Disinfection of article surfaces

When the surface of objects is disinfected by means of irradiation, it is better to use a portable ultraviolet sterilizer to move in a short distance for irradiation, or ultraviolet disinfection lamps suspension irradiation can be adopted. Small items can be placed in the ultraviolet disinfection box for irradiation. Because different kinds of microorganisms have different sensitivity to ULTRAVIOLET radiation, the irradiation dose must be used to achieve the target microorganisms. Should the dose of radiation be 10000 W.s/cm for killing general bacterial propagules? ; The killing of bacterial bud should reach 100000 W.s/cm2; The resistance of the virus to UV is between the bacterial propagator and the bud. Fungal spores are more resistant than bacterial spores, sometimes requiring irradiation of up to 600000 W s/cm2. When the target microorganism for disinfection is unknown, the irradiation dose should not be lower than 100 000 W.s/cm2. The irradiation dose is the product of the irradiation intensity and irradiation time of the ultraviolet lamp on the surface of the irradiated object. Therefore, according to the irradiation intensity of ultraviolet light source, the time needed for irradiation can be calculated.

4.2.2 Disinfection of indoor air

When using indirect irradiation method to disinfect indoor air, the first choice is high-intensity ultraviolet air sterilizer, which not only has reliable disinfection effect, but also can be used when someone is active indoors. Generally, it can be disinfected for 30 minutes after starting the machine. The indoor air can also be disinfected by direct illumination under the condition of no one in the room. The ultraviolet disinfection lamps can be suspended or movable type for direct irradiation. When indoor suspended uv disinfection is used, the number of indoor uv disinfection lamps (30W UV lamps with an intensity greater than 70 W/cm2 at 1.0m) should be installed in such a way that each side is not less than 1.5w on average and the exposure time is not less than 30min.

4.2.3 Disinfection of water and other liquids

Disinfection of water and other liquids may be performed by in-water or out-water irradiation. When using the method of in-water illumination, the ultraviolet light source should be equipped with quartz glass protective cover. Whatever method is adopted, the water layer thickness should be less than 2cm, and the water flow velocity should be determined according to the intensity of ultraviolet light source. The disinfected water must meet the hygienic standard set by the State.

4.3 Matters needing attention when applying ultraviolet disinfection lamps

It is to be in use process above all, should maintain the clean of ultraviolet lamp surface, use alcohol cotton ball to wipe with average every two weeks, when discovering lamp tube surface has dirt, greasy dirt, should wipe at any time. Secondly, when using ultraviolet disinfection lamp to disinfect indoor air, the room should be kept clean and dry to reduce dust and water mist. When the temperature is lower than 20°C or higher than 40°C, and the relative humidity is greater than 60%, the irradiation time should be appropriately extended. However, when using ultraviolet radiation to disinfect the surface of articles, the irradiated surface should be directly irradiated by ultraviolet radiation, and the irradiated dose should be sufficient. Finally, great care must be taken not to expose the ultraviolet light to human eyes or exposed skin, lest the bow burn.

For more knowledge about ultraviolet disinfection lamps, welcome to contact Tepro ultraviolet disinfection lamps manufacturer.

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