Design and development of ultraviolet disinfection lamp
Design and development of ultraviolet disinfection lamp
1. The principle of ultraviolet disinfection
At present, disinfection methods can be divided into two categories, namely chemical disinfection methods and physical disinfection methods. Chemical disinfection methods include chlorine disinfection and ozone disinfection; physical disinfection methods include ultraviolet disinfection. The principle of ultraviolet sterilization and disinfection is to use appropriate wavelengths of ultraviolet light to destroy the molecular structure of DNA (deoxyribonucleic acid) or RNA (ribonucleic acid) in the cells of microorganisms, resulting in growth cell death and/or regenerative cell death, to achieve sterilization and disinfection Effect. After testing, 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 the UVA and UVB parts can reach the earth's surface through the ozone protective layer and the cloud layer. In terms of sterilization speed, UVC is within the range of microbial absorption peaks, which can kill viruses and bacteria by destroying the DNA structure of microbes within 1s, while UVA and UVB are outside the range of microbial absorption peaks, the sterilization speed is very slow, It often takes several hours to play a sterilizing role. During the hydraulic retention (irradiation) time of a few seconds in the actual project, this part is actually an invalid ultraviolet part. The penetration of vacuum ultraviolet light is extremely weak, and the lamps and sleeves need to use extremely high transmittance quartz. Generally, the semiconductor industry is used to degrade TOC in water, and it is not used for sterilization. Therefore, the ultraviolet disinfection in water supply and drainage engineering actually refers to UVC disinfection. Ultraviolet disinfection technology is based on modern epidemiology, medicine and photodynamics, and uses specially designed high-efficiency, high-strength and long-life UVC band ultraviolet light to irradiate flowing water to expose various bacteria, viruses, parasites and algae in the water. And other pathogens are directly killed to achieve the purpose of disinfection.
Studies have shown that ultraviolet light mainly kills microorganisms by radiating damage to microorganisms (bacteria, viruses, spores and other pathogens) and destroying the function of nucleic acids, thereby achieving the purpose of disinfection. The effect of ultraviolet rays on nucleic acids can lead to the breaking of bonds and chains, cross-strand crosslinking and the formation of photochemical products, etc., thereby changing the biological activity of DNA and preventing the microorganisms from replicating themselves. This ultraviolet damage is also a lethal damage. Ultraviolet disinfection is a physical method. It does not add any substances to the water and has no side effects. This is where it is superior to chlorinated disinfection. It is usually used in combination with other substances.
Ultraviolet light is a light wave that is invisible to the naked eye and exists outside the ultraviolet end of the spectrum, so it is called ultraviolet light. According to different wavelength ranges, it is divided into three bands, A, B, and C, of which the C band ultraviolet wavelength is 240. Between 260nm, it is the most effective sterilization band.
Modern ultraviolet disinfection technology is based on modern epidemiology, optics, biology and physical chemistry, using a specially designed high-efficiency, high-strength and long-life C-band ultraviolet light generating device to generate strong ultraviolet C light to irradiate air or On the surface of the object, when various bacteria, viruses, parasites, algae and other pathogens in the air or solid surface are irradiated with a certain dose of ultraviolet C light, the DNA structure in their cells is destroyed, so that without the use of any chemical drugs Under circumstances, kill bacteria, viruses, and other pathogens to achieve the purpose of disinfection and purification. It has the advantages of high efficiency, broad spectrum, low price, long life, easy operation, low operating cost and no secondary pollution.
Ultraviolet light is a light shorter than the wavelength of visible light. It can be divided into three types according to the wavelength: A light: short-term effects will cause redness, tanning, light-sensitive reactions, and long-term wrinkles, dark spots, and skin aging. B light: The short-term effects are sunburn, sunburn, and sunburn. The long-term effects will cause 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 skin cancer will occur in the long term.
We can clearly understand that it is the B light that is easy to cause sunburn; that is, when you are happily going to the beach to get red and painful, and take off a layer of skin, it is the short-term effect of ultraviolet B light. The "indoor ultraviolet tanning method" is to use the principle of "prosperity and avoid evil", avoid ultraviolet B light, only use ultraviolet A light, so that the effect of tanning can be achieved in a short period of time, but there is no worry about sunburn. That is, in a machine equipped with many ultraviolet A light tubes, gradually increase the exposure time to achieve the purpose of gradually blackening.
Second, the advantages of ultraviolet disinfection
UV disinfection does not require chemicals and will not produce THMs-like disinfection by-products. Fast sterilization and good effect. No odor, no noise, does not affect the taste of water. It is easy to operate, simple to manage, and has low operation and maintenance costs.
Most ultraviolet devices use traditional low-pressure ultraviolet lamp technology, and some large water plants use low-pressure high-intensity ultraviolet lamp systems and medium-pressure high-intensity ultraviolet lamp systems. Due to the generation of high-intensity ultraviolet rays, the number of lamps may be reduced by more than 90%, thus Reduced floor space and saved installation and maintenance costs.
Third, the scope and conditions of ultraviolet disinfection
(1) Ultraviolet rays can kill all kinds of microorganisms, including bacterial propagules, spores, mycobacteria, viruses, fungi, rickettsiae and mycoplasma. Any surface contaminated with the above microorganisms, water and air can be disinfected with ultraviolet light.
(2) The ultraviolet radiation has low energy and weak penetration, and can only kill the microorganisms that are directly irradiated. Therefore, when disinfecting, the disinfection site must be fully exposed to ultraviolet light.
(3) When sterilizing rough surfaces such as paper and fabrics with ultraviolet light, the irradiation time should be properly extended, and both sides should be exposed.
(4) The most suitable temperature range for UV disinfection is 20-40 ℃, the temperature is too high or too low will affect the disinfection effect, you can properly extend the disinfection time, when used for air disinfection, the relative humidity of the disinfection environment is better than 80% Otherwise, the irradiation time should be properly extended.
(5) When ultraviolet rays are used to kill microorganisms protected by organic matter, the irradiation dose should be increased. Airborne particles can also affect the disinfection effect.
Fourth, the use of ultraviolet disinfection lamp
The intelligent controller pre-sets the combination password, which is as simple as possible for the staff to remember. When the password is not entered at this time, the key UV lamp is turned off without power to prevent the patient and family members from accidentally pressing the switch to turn on by mistake.
During irradiation, various personnel leave the disinfection place and close the door. Enter the preset combination password, set the irradiation time, the switch is closed, the timer starts timing, the ultraviolet disinfection lamp is on, the screen shows the irradiation time, and the cumulative timer starts to work. When the irradiation time is up, the timer switch is closed. During the irradiation process, if the door is pushed open to enter the room, the ultraviolet switch will automatically turn off the disinfection lamp and emit an alarm sound. At this time, close the door first, and then on the panel, follow the instructions on the LCD screen to turn on the ultraviolet lamp again (continue to disinfect according to the remaining time) or turn off the ultraviolet lamp completely to end the alarm.
(1) Disinfection method on the surface of the article: the irradiation method is best to use a portable ultraviolet sterilizer to move the irradiation at a short distance, or to suspend the irradiation with an ultraviolet lamp. Small items can be irradiated in the ultraviolet disinfection box.
Irradiation dose and time Different types of microorganisms have different sensitivities to ultraviolet rays. When disinfecting with ultraviolet rays, the irradiation dose must be used to reach the irradiation dose required to kill the target microorganisms. When killing general bacterial propagules, the irradiation dose should reach 10000uW. s/em2; when killing bacterial spores should reach 100000uW. s/Cm; the resistance of viruses to ultraviolet light is between bacterial propagules and spores; the resistance of fungal spores is stronger than that of bacterial spores, and sometimes needs to be irradiated to 600,000uW. s/Cm2; when the target microorganism for disinfection is unknown, the irradiation dose should not be lower than 100,000uW. s/Cm2. The irradiation dose is the product of the irradiation intensity of the ultraviolet lamp used to irradiate the surface of the article and the irradiation time. Therefore, according to the irradiation intensity of the ultraviolet light source, the time required for irradiation can be calculated. For example, an ultraviolet surface sterilizer with an irradiation intensity of 70uW/Cm2 is used to irradiate the surface of the article at close range; the selected irradiation dose is one 100,000uW. s/Cm; the exposure time is: 100,000uW. s/Cm2÷70uW/Cm2=24 minutes.
(2) Disinfection method for indoor air: Indirect irradiation method is preferred high-intensity ultraviolet air sterilizer, not only can disinfect the effect, but also can be used when there are people indoor activities, generally start disinfection. 30rain can achieve disinfection qualification. The direct irradiation method can adopt the suspension type or mobile type direct irradiation of the ultraviolet lamp in the indoor unmanned condition. When using indoor suspended ultraviolet disinfection, the number of ultraviolet disinfection lamps (30W ultraviolet lamps, intensity >1.0uW/Cm at 1.0 meters) installed indoors is an average of not less than 1.5W per cubic meter, and the irradiation time is not less than 30min.
V. Precautions for using ultraviolet disinfection lamp
(1) During use, the surface of the UV lamp should be kept clean. Generally, wipe with a 95% alcohol-free cotton ball once a week. If there is dust or oil on the surface of the lamp, wipe it at any time. (2) When disinfecting indoor air with ultraviolet light. The room should 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 should be properly extended. (3) When disinfecting the surface of articles with ultraviolet rays, the irradiated surface should be directly irradiated with ultraviolet rays, and sufficient irradiation dose should be achieved. Do not expose the ultraviolet light source to people to avoid damage.
6. Design and realization of ultraviolet disinfection lamp
Ultraviolet disinfection lamp is a common tool for air disinfection in many domestic hospitals. It is the most convenient and economical disinfection method, and it is also an important facility for controlling hospital infections. Ultraviolet rays can kill a variety of microorganisms, including bacterial propagules, bacterial spores, tubercle bacillus, fungi, viruses, and Rickettsia, etc. It is widely used in hospitals and other public places, especially grassroots hospitals. However, ultraviolet rays have the adverse effect of killing normal cells, so the human body should not directly illuminate the ultraviolet lamp. Investigations in multiple hospitals have found that the ultraviolet light switch is the same as and adjacent to the ordinary fluorescent light switch, and the patient or family members accidentally turn on the wrong ultraviolet light and cause injury to the human body. In addition, the nursing staff should control the disinfection time when using the ultraviolet lamp to disinfect, record the cumulative exposure time of the lamp, etc. In response to the above situation, we have developed an intelligent controller for ultraviolet disinfection lamp, which is introduced as follows.
The design function of the intelligent controller of the ultraviolet disinfection lamp is to prevent accidental opening, enter the room to alarm and automatically close when irradiated, set the irradiation time, record the cumulative irradiation time of the lamp, etc. The design of the switch panel is the same as the national standard 86 type switch. It is powered by a single live wire and can be modified on the ordinary switch. There are LED lights and LCD screens on the switch panel. The appearance is shown in Figure 1, with the following functions:
(1) Timed irradiation design. Design a timer switch, half an hour or an hour after the start of irradiation (multiple exposure time can be set to select), the timer will be automatically closed after the end of the timer; it can also be manually closed by the switch on the panel. There are LED lights and LCD screen on the switch panel to indicate the working status of the ultraviolet disinfection lamp.
(2) Automatically record the cumulative use time of ultraviolet lamps. When the UV lamp is lit, it will automatically count the time. When the light is turned off, the timing will be stopped. The original timing data will not be lost when the power is turned off. The timing will continue on the original timing data after the power is turned on; the timing accuracy is less than 15min, and the timing range is 0 to 6000h (general UV The lamp life is 4000h), can be set to zero (replace the lamp); the cumulative hours of use of the ultraviolet lamp (h) can be displayed on the LCD screen of the switch panel in real time.
(3) Safe automatic protection function. Install a magnetic sheet and a magnetic sensor on the door of the disinfection room to detect the opening and closing status of the door to prevent injuries caused by accidental entry of personnel during the disinfection of the ultraviolet lamp. When the door is closed, the ultraviolet disinfection lamp in the room can be turned on by the ultraviolet switch (designed to be installed outside the disinfection room). During the disinfection process of the ultraviolet lamp, if someone opens the door by mistake, the ultraviolet switch will automatically turn off the disinfection lamp and emit an alarm sound. At this time, close the door first, and then on the panel, follow the instructions on the LCD screen to turn on the ultraviolet lamp again (continue to disinfect according to the remaining time) or turn off the ultraviolet lamp completely to end the alarm.
(4) Switch password anti-misoperation function. In order to prevent normal non-workers from accidentally turning on the disinfection lamp outdoors to cause harm to patients indoors, the switch is designed to have a power-on password function. That is, after turning on the switching power supply, you need to enter the preset key combination before you can enter the function use interface and use the switching function. The system framework diagram is shown in Figure 2.
Seven, the advantages of ultraviolet disinfection lamp controller
(1) Prevent the patients and their families from accidentally turning on the ultraviolet light switch: the traditional ultraviolet disinfection switch is a common switch device placed indoors, which is easy to be injured by the patients or their families by misoperation. Ultraviolet rays damage the human skin and eyes, which can cause skin Burns, corneal inflammation, skin cancer, etc.; ozone generated by ultraviolet rays promotes aging, the smell is unacceptable, and too much inhalation will poison people. Ozone enters the blood and competes with hemoglobin for oxygen, so it can only be sterilized by air in the absence of people.
The switch of the device has a power-on password function, that is, after the power of the switch is turned on, the preset key combination must be input before entering the function use interface and using the switch function. Prevent the patients or their families from accidentally turning on the ultraviolet disinfection lamp outdoors to cause iatrogenic and occupational injuries to indoor patients.
(2) Automatically protect the human body from ultraviolet radiation: install magnetic sheets and magnetic sensors on the corresponding positions of the door and the door frame to detect the opening and closing state of the door. During the disinfection of the ultraviolet lamp, if a person accidentally enters the irradiation area, the ultraviolet switch will automatically turn off the disinfection lamp and emit an alarm sound. Close the door, and follow the instructions on the LCD screen to turn on the UV lamp again (continue to disinfect according to the remaining time) or turn off the UV lamp completely to end the alarm.
(3) Automatic timing and time-exposure exposure time to ensure the quality of disinfection and facilitate the staff to record: the traditional ultraviolet disinfection mode is a manual control switch, manual timing, from light on-time-light off-record, each lamp is registered daily Disinfection time and cumulative use time increase the workload of nurses. This completely manual mechanical operation mode, not only the process is cumbersome, but the nursing staff must also take care of other tasks, often forget to time after turning on the lamp, causing the ultraviolet irradiation time to be too long or too short, which is arbitrary and affects the quality of disinfection. After installing the intelligent control switch, it will automatically turn off and accumulate after setting the irradiation time. The timing range is 0～6000h (usually the service life of the ultraviolet lamp is 4000h). After replacing the lamp, you can set it to zero and retime. The cumulative hours of use (h) of the UV lamp can be displayed on the LCD screen of the switch panel in real time to achieve complete automation. Simply record the time to install or replace the UV lamp to design a timer switch.
to sum up
In summary, the intelligent controller for ultraviolet disinfection lamps in this study can improve the safety of ultraviolet disinfection lamps, reduce human workload, and provide a safe, effective, and convenient disinfection work method.