The
clean bench is a one-way flow air purification device that provides a local dust-free and sterile working environment.
It is widely used in scientific research and production departments that require a local clean and sterile working environment, such as medicine and health, biopharmaceuticals, food, medical science experiments, optics, electronics, sterile room experiments, sterile microbiological testing, and plant tissue culture inoculation. It can also be connected to an assembly production line with the advantages of low noise and mobility. It is a highly versatile air purification device that provides a local high-cleanliness working environment. Its use has a good effect on improving process conditions, improving product quality and increasing the yield rate.
Note: The clean bench is different from the biosafety cabinet. The clean bench can only protect the reagents operated in the bench from contamination, but does not protect the staff, while the biosafety cabinet is a negative pressure system that can effectively protect the staff.
1. Working principle
The principle of the clean bench is that in a specific space, the indoor air is initially filtered by the pre-filter, pressed into the static pressure box by a small centrifugal fan, and then filtered by the air high-efficiency filter for the second time. The clean airflow blown out from the air outlet of the air high-efficiency filter has a certain and uniform cross-sectional wind speed, which can remove the original air in the work area and take away dust particles and biological particles to form a sterile and highly clean working environment.
2. Product classification
From the direction of airflow, it is divided into: vertical flow clean bench and horizontal flow clean bench; the clean bench is divided into single-person workbench and double-person workbench according to the number of operators; the clean bench is divided into conventional type and new push-pull and self-circulation type (vertical flow only) according to the structure.
According to the direction of airflow, the clean bench is divided into vertical flow clean bench and horizontal flow clean bench. The vertical flow bench has a larger noise because the fan is at the top, but the vertical wind is mostly used in fields such as medical engineering to ensure people's health; the horizontal flow bench has a relatively small noise and the wind is outward, so it is mostly used in the electronics industry and has little effect on health. According to the operation structure, it can be divided into two forms: unilateral operation and bilateral operation. According to its use, it can be divided into ordinary clean bench and biological (medical) clean bench.
3. Precautions
The power supply of the clean bench mostly adopts three-phase four-wire, of which there is a neutral wire, which is connected to the machine casing and should be firmly connected to the ground wire. The other three wires are phase wires, and the working voltage is 380V. There is a certain order in the three-wire access circuit. If the wire head is connected incorrectly, the fan will reverse. At this time, the sound is normal or slightly abnormal. There is no wind on the front of the clean bench (the flame of the alcohol lamp can be used to observe the movement, and it is not suitable to test for a long time). The power supply should be cut off in time, and the wire heads of any two phases can be swapped and connected. If the three-phase line is only connected to two phases, or one of the three phases has poor contact, the machine sound is very abnormal, and the power supply should be cut off immediately for careful inspection, otherwise the motor will burn out. These common sense should be explained clearly to the staff when the clean bench is used.
The air inlet of the clean bench is at the bottom of the back or front. There is a common foam plastic sheet or non-woven fabric in the metal mesh cover to block large particles of dust. It should be checked and cleaned frequently. If the foam plastic is found to be aging, it should be replaced in time. In addition to the air inlet, if there are leaking holes, they should be blocked tightly, such as sticking tape, stuffing cotton, sticking glue paper, etc. The metal mesh cover on the front of the workbench is a super filter, which can also be replaced. If it is used for a long time, the dust particles are blocked, the wind speed is reduced, and the sterile operation cannot be guaranteed, it can be replaced with a new one.
The service life of the clean bench is related to the cleanliness of the air. In temperate regions, the clean bench can be used in general laboratories. However, in tropical or subtropical regions, because the atmosphere contains a lot of pollen or dusty areas, the clean bench should be placed in a better room with double doors for use. In any case, the air inlet cover of the clean bench should not be facing an open door or window to avoid affecting the service life of the filter.
The sterile room should be regularly sprayed with 75% alcohol or 0.5% phenol to reduce dust and disinfect, 2% Sanisol should be used to wipe the table and utensils (70% alcohol can also be used), and formalin (40% formaldehyde) plus a small amount of potassium permanganate should be used for regular closed fumigation, and disinfection and sterilization methods such as ultraviolet sterilization lamps (open for more than 15 minutes each time) should be used to keep the sterile room sterile. The inoculation box should also be equipped with ultraviolet lamps. Before use, turn on the lamp for more than 15 minutes for irradiation and sterilization, but all places that cannot be irradiated are still bacteria. When the ultraviolet lamp is turned on for a long time, it can stimulate the oxygen molecules in the air to form ozone molecules. This gas molecule has a strong bactericidal effect and can produce a sterilizing effect on corners that are not directly illuminated by ultraviolet rays. Because ozone is harmful to health, the ultraviolet lamp should be turned off before entering the operation, and you can wait for more than ten minutes before entering.
Ultraviolet lamps can also be suspended on the ultra-clean workbench, but they should be installed outside the lighting lampshade and the arrangement of the lighting lamps should be staggered so that they do not hinder lighting during work. If the ultraviolet lamp is placed inside the lighting lampshade (glass plate), it is useless because ultraviolet rays cannot penetrate glass. Its lamp tube is quartz glass, not silicate glass.
The inoculation room strives to be simple. Any items that are not directly related to the work of this room cannot be placed in order to maintain sterility. The air in the inoculation room should be absolutely isolated from the outside air, and the reserved ventilation channel should be as closed as possible. The ventilation channel can be equipped with upper and lower air windows, the area of the air window should be slightly larger, and it needs to be covered with 4 layers of gauze for simple dust filtration. After a day's work, the window can be opened for full ventilation and then sealed. In short, it is clean, dust-free and sterile, and the air is fresh and suitable for work. The gauze covering the ventilation window should be changed and washed frequently. However, the above measures are only ideal design solutions, which are often not easy to achieve comprehensively. In fact, as long as the aseptic operation procedures are strictly followed, in the room with open doors and windows, there is a clean bench for protection, and the inoculation contamination rate can still be controlled at a tolerable level in production.
4. Daily maintenance points
Regular maintenance and maintenance play an important role in extending the service life of the clean bench.
Keep the room dry and clean. Humid air can not only cause the manufacturing materials to rust, but also affect the normal operation of the electrical circuit. Humid air is also conducive to the growth of bacteria and fungi. A clean environment can extend the service life of the filter plate.
Regular cleaning of the equipment is an important part of normal use. Cleaning should include routine cleaning before and after use and regular fumigation. During fumigation, all gaps should be completely sealed.
The filter plates and ultraviolet germicidal lamps of the clean bench have a calibrated service life and should be replaced on schedule.
