Design and development of ultraviolet disinfection lamp
Design and development of ultraviolet disinfection lamp
1、 Principle of ultraviolet disinfection
At present, disinfection methods can be divided into two categories: chemical disinfection and physical disinfection. Chemical disinfection methods include chlorination and ozone disinfection; Physical disinfection methods include ultraviolet disinfection, etc. The principle of ultraviolet sterilization and disinfection is to use ultraviolet light of appropriate wavelength to destroy the molecular structure of DNA (deoxyribonucleic acid) or RNA (ribonucleic acid) in microbial body cells, resulting in growth cell death and / or regenerative cell death, so as to achieve the effect of sterilization and disinfection. Through experiments, the effective wavelength range of ultraviolet sterilization can be divided into four different bands: UVA (400-315nm), UVB (315-280nm), UVC (280-200nm) and vacuum ultraviolet (200-100nm). Among them, only UVA and UVB can reach the earth's surface through the ozone protective layer and clouds. In terms of sterilization speed, UVC is within the range of microbial absorption peak and can kill viruses and bacteria by destroying the DNA structure of microorganisms within 1s. However, UVA and UVB are outside the range of microbial absorption peak, and the sterilization speed is very slow. It often takes several hours to play the role of sterilization. Within the hydraulic retention (irradiation) time of several seconds in the actual project, This part is actually an invalid UV part. The penetration ability of vacuum ultraviolet light is very weak. The lamp tube and sleeve need to use quartz with extremely high light transmittance. Generally, the semiconductor industry is used to degrade TOC in water, which is not used for sterilization and disinfection. Therefore, the ultraviolet disinfection in water supply and drainage engineering actually refers to UVC disinfection. Ultraviolet disinfection technology is based on modern epidemic prevention, medicine and photodynamics. It uses specially designed UVC band ultraviolet light with high efficiency, high intensity and long life to irradiate the running water to directly kill various bacteria, viruses, parasites, algae and other pathogens in the water, so as to achieve the purpose of disinfection.
Research shows that ultraviolet radiation can kill microorganisms by damaging the function of nucleic acid and damaging microorganisms (bacteria, viruses, spores and other pathogens), so as to achieve the purpose of disinfection. The effect of ultraviolet on nucleic acid can lead to bond and chain breaking, inter strand crosslinking and the formation of photochemical products, which can change the biological activity of DNA and make microorganisms unable to replicate themselves. This ultraviolet damage is also fatal. Ultraviolet disinfection is a physical method. It does not add any substances to the water and has no side effects. This is its advantage over chlorination disinfection. It is usually used in combination with other substances.
Ultraviolet is a kind of light wave invisible to the naked eye, which exists outside the ultraviolet end of the spectrum, so it is called ultraviolet. According to different wavelength ranges, it is divided into three bands: A, B and C. among them, the C band ultraviolet wavelength is between 240-260nm, which is the most effective sterilization band.
Modern ultraviolet disinfection technology is based on modern epidemic prevention, optics, biology and physical chemistry, and uses the specially designed high-efficiency, high-intensity and long-life C-band ultraviolet generator to irradiate the air or object surface with strong ultraviolet C light After algae and other pathogens are irradiated by a certain dose of ultraviolet C light, the DNA structure in their cells is destroyed, so as to kill bacteria, viruses and other pathogenic bodies without using any chemical drugs, so as to achieve the purpose of disinfection and purification. It has the advantages of high efficiency, broad spectrum, low price, long life, simple operation, low operation cost and no secondary pollution.
Ultraviolet is a kind of light shorter than the wavelength of visible light. It can be divided into three types according to the wavelength: a light: the short-term effect will cause sunburn, tanning and light sensitivity, and the long-term effect will produce wrinkles, black spots and skin aging. B light: the short-term effects are redness, tanning and sunburn, and the long-term effects include wrinkles, dark spots and skin cancer. C light: because the ozone layer cannot reach the surface, it cannot be seen in the short term, but it will produce skin cancer in the long term.
We can clearly understand that B light is easy to cause sunburn; In other words, when you go to the beach happily, you get red and painful, and take off a layer of skin to come back, which is the short-term effect of ultraviolet B light. "Indoor ultraviolet tanning method" is to use the principle of "seeking good luck and avoiding bad luck", avoid ultraviolet B light and only use ultraviolet a light, so that the tanning effect can be achieved in the short term, but there is no concern of sunburn. That is, in the machine equipped with many ultraviolet a light tubes, gradually increase the exposure time to achieve the purpose of gradually blackening.
2、 Advantages of ultraviolet disinfection
UV disinfection does not require chemicals and will not produce THMs disinfection by-products. Fast sterilization and good effect. No odor, no noise, no impact on the taste of water. Easy operation, simple management, low operation and maintenance costs.
Most UV devices use the traditional low-voltage UV lamp technology, and some large water plants use low-voltage high-intensity UV lamp system and medium voltage high-intensity UV lamp system. Due to the generation of high-intensity UV, the number of lamps may be reduced by more than 90%, thus reducing the floor area and saving installation and maintenance costs.
3、 Application scope and conditions of ultraviolet disinfection
(1) Ultraviolet rays can kill various microorganisms, including bacterial propagules, spores, mycobacteria, viruses, fungi, Rickettsia and mycoplasma. All surfaces polluted by the above microorganisms, water and air can be disinfected by ultraviolet rays.
(2) Ultraviolet radiation has low energy and weak penetration, which can only kill directly irradiated microorganisms. Therefore, during disinfection, the disinfected parts must be fully exposed to ultraviolet light.
(3) When disinfecting rough surfaces such as paper and fabric with ultraviolet light, the irradiation time shall be appropriately extended, and both sides shall be irradiated.
(4) The most suitable temperature range for ultraviolet disinfection is 20-40 ℃. If the temperature is too high or too low, it will affect the disinfection effect. The disinfection time can be extended appropriately. When used for air disinfection, the relative humidity of the disinfection environment should be less than 80%, otherwise the irradiation time should be extended appropriately.
(5) When killing microorganisms protected by organic matter with ultraviolet light, the irradiation dose should be increased. Suspended particles in the air can also affect the disinfection effect.
4、 Usage of ultraviolet disinfection lamp
The combination password is preset by the intelligent controller, which is as simple as possible and easy for the staff to remember. At this time, if the password is not entered, press the key to turn on, and the ultraviolet lamp is not powered on, so as to prevent the patient and his family from pressing the switch by mistake.
During irradiation, all kinds of personnel leave the disinfection place and close the door. Input the preset combination password, set the irradiation time, the switch is closed, the timer starts counting, the ultraviolet disinfection lamp is on, the screen displays the irradiation time, and the cumulative timer starts working. When the irradiation time is up, the timing switch is closed. During irradiation, if the door is pushed into the room, the ultraviolet switch will automatically turn off the disinfection lamp and sound an alarm. At this time, close the room door first, and then press the prompt on the LCD screen on the panel to turn on the ultraviolet lamp again (continue disinfection according to the remaining time) or completely turn off the ultraviolet lamp before ending the alarm.
(1) Disinfection method for the surface of articles: it is best to use portable ultraviolet sterilizer for close mobile irradiation, or UV lamp suspension irradiation. Small items can be irradiated in the ultraviolet disinfection box.
Different kinds of microorganisms have different sensitivity to ultraviolet radiation. When disinfecting with ultraviolet radiation, the irradiation dose must be used to achieve the irradiation dose required to kill the target microorganisms. When killing common bacterial propagules, the irradiation dose should reach 10000uw.s/em2; When killing bacterial spores, it should reach 100000 uw.s/cm; The resistance of virus to ultraviolet light is between bacterial propagules and spores; Fungal spores are more resistant than bacterial spores, and sometimes need to be irradiated to 600000 UW. S / cm2; When the target microorganism for disinfection is unknown, the irradiation dose shall not be less than 100000 uw.s/cm2. The irradiation dose is the product of the irradiation intensity and irradiation time of the ultraviolet lamp at the surface of the irradiated article. Therefore, the time to be irradiated can be calculated according to the irradiation intensity of the ultraviolet light source. For example, an ultraviolet surface sterilizer with an irradiation intensity of 70uw / cm2 is used to irradiate the surface of the article at a close distance; The selected irradiation dose is 100000 UW. S / cm; The irradiation time is 100000 UW. S / cm2 ÷ 70uw / cm2 = 24 minutes.
(2) Disinfection method for indoor air: high intensity ultraviolet air sterilizer is preferred for indirect irradiation method. It can not only have a good disinfection effect, but also be used when there are people in the room. Generally, it can be disinfected by turning on the machine for 30 rain. Direct irradiation method under the condition of no one in the room, UV lamp suspension or mobile direct irradiation can be adopted. When indoor suspended ultraviolet disinfection is adopted, the number of ultraviolet disinfection lamps (30W ultraviolet lamps, intensity > 70uw / cm at 1.0m) installed indoors shall not be less than 1.5W per cubic meter, and the irradiation time shall not be less than 30min.
5、 Precautions for using ultraviolet disinfection lamp
(1) During use, the surface of the ultraviolet lamp shall be kept clean. Generally, it shall be wiped once a week with 95% absolute alcohol cotton ball. When dust and oil stain are found on the surface of the lamp, it shall be wiped at any time. (2) When disinfecting indoor air with ultraviolet lamp. The room shall be kept clean and dry to reduce dust and water mist. When the temperature is lower than 2O ℃ or higher than 4O ℃ and the relative humidity is greater than 60%, the irradiation time shall be extended appropriately. (3) When disinfecting the surface of articles with ultraviolet light, the irradiated surface shall be directly irradiated by ultraviolet light, and sufficient irradiation dose shall be achieved. Do not irradiate people with ultraviolet light source to avoid damage.
6、 Design and Realization of ultraviolet disinfection lamp
Ultraviolet disinfection lamp is a common tool for air disinfection in many hospitals in China. It is not only the most convenient and economical disinfection method, but also an important facility to control nosocomial infection. Ultraviolet light can kill various microorganisms, including bacterial propagules, bacterial spores, Mycobacterium tuberculosis, fungi, viruses and Rickettsia. It is widely used in hospitals and other public places, especially grass-roots hospitals. However, ultraviolet rays have adverse reactions that kill normal cells, so the human body should not directly illuminate ultraviolet lamps. The investigation of many hospitals found that the UV lamp switch is the same as and adjacent to the ordinary fluorescent lamp switch, and the patient or family members mistakenly turn on and illuminate the UV lamp, resulting in human injury. In addition, when using ultraviolet lamp for disinfection, nurses should control the disinfection time and record the cumulative irradiation time of the lamp. In view of the above situation, we have developed an intelligent controller for ultraviolet disinfection lamp, which is introduced as follows.
The design functions of the intelligent controller of ultraviolet disinfection lamp are to prevent false opening, alarm and automatic closing in case of irradiation, set the irradiation time, record the cumulative irradiation time of the lamp, etc. The design size of the switch panel is the same as that of the national standard 86 switch. It is powered by single live wire and can be refitted on an ordinary switch. There are led lights and LCD screen on the switch panel. The appearance is shown in Figure 1. It has the following functions:
(1) Timing irradiation design. Design the timing switch, half an hour or one hour after the start of irradiation (multiple irradiation times can be set and selected), and the timing will be closed automatically after the end of timing; It can also be turned off manually through the switch on the panel. There are led lights and LCD screens on the switch panel to indicate the working status of the ultraviolet disinfection light.
(2) Automatically record the cumulative service time of ultraviolet lamp. When the ultraviolet lamp is on, it will automatically accumulate timing. When the lamp is off, it will stop timing. When the power is off, the original timing data will not be lost. After power on, it will continue timing on the original timing data; The timing accuracy is less than 15min, the timing range is 0 ~ 6000h (the service life of general ultraviolet lamp is 4000H), and zero clearing can be set (replace the lamp); The cumulative service hours (H) of the ultraviolet lamp can be displayed on the LCD screen of the switch panel in real time.
(3) Automatic safety protection function. Install magnetic plates and magnetic sensors on the door of the disinfection room to detect the opening and closing state of the door and prevent personnel from entering by mistake during the disinfection process of ultraviolet lamp. When the door is closed, the indoor ultraviolet disinfection lamp can be turned on through the ultraviolet switch (designed to be installed outside the disinfection room). During the disinfection process when the ultraviolet lamp is turned on, if someone opens the door by mistake, the ultraviolet switch will automatically turn off the disinfection lamp and sound an alarm. At this time, close the room door first, and then press the prompt on the LCD screen on the panel to turn on the ultraviolet lamp again (continue disinfection according to the remaining time) or completely turn off the ultraviolet lamp before ending the alarm.
(4) Switch password anti misopening function. In order to prevent non staff from accidentally opening the disinfection lamp outdoors and causing harm to indoor patients, the switch is designed to have the function of power on password. That is, after turning on the switching power supply, you need to input the preset combination key before entering the function interface to use the switching function. The system framework is shown in Figure 2.
7、 Advantages of UV disinfection lamp controller
(1) Prevent patients and their families from turning on the ultraviolet lamp switch by mistake: the traditional ultraviolet disinfection switch is an ordinary switching device placed indoors, which is easy to be injured by the misoperation of patients or their families. Ultraviolet rays are harmful to human skin and eyes, and can cause skin burns, corneal inflammation, skin cancer, etc; Ozone produced by ultraviolet rays can age people, and its smell is unacceptable. If inhaled too much, people will be poisoned. Ozone enters the blood to compete with hemoglobin for oxygen, so air disinfection can only be carried out without people.
The switch of the device has the function of power on password, that is, after turning on the switching power supply, you need to input the preset combination key before entering the function interface and using the switch function. Prevent patients or family members from accidentally opening ultraviolet disinfection lamps outdoors, causing iatrogenic and occupational injuries to indoor patients.
(2) Automatic protection of human body from ultraviolet radiation: install magnetic sheets and magnetic sensors at the corresponding positions of the door and door frame to detect the opening and closing state of the door. In the process of ultraviolet lamp disinfection, if personnel enter the irradiation area by mistake, the ultraviolet switch will automatically turn off the disinfection lamp and sound an alarm. Close the room door, press the prompt on the LCD screen on the panel, turn on the ultraviolet lamp again (continue disinfection according to the remaining time) or turn off the ultraviolet lamp completely to end the alarm.
(3) Automatic timing and time-consuming irradiation time ensure the disinfection quality and facilitate the staff to record: the traditional ultraviolet disinfection mode is manual switch, manual timing, from light on timing off recording. Each lamp tube registers the disinfection time and cumulative use time day by day, increasing the workload of nurses. This completely manual and mechanical operation mode is not only cumbersome, but also nurses should take into account other work. After turning on the light, they often forget to time, resulting in too long or too short ultraviolet irradiation time, great randomness and affecting the disinfection quality. After the intelligent control switch is installed, it will automatically turn off and automatically accumulate after the irradiation time is set. The timing range is 0 ~ 6000h (the service life of the general ultraviolet lamp is 4000H). After the lamp is replaced, it can be reset and timed again. The cumulative service hours (H) of the ultraviolet lamp can be displayed on the LCD screen of the switch panel in real time to realize complete automation. Only record the time of installing or replacing the UV lamp, and design the timing switch.
summary
In conclusion, the intelligent controller of ultraviolet disinfection lamp in this study can improve the safety of ultraviolet lamp disinfection, reduce people's workload, and provide a safe, effective and simple disinfection mode.