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How to judge whether the airflow of the clean workbench is normal?
How to judge whether the airflow of the clean workbench is normal?First, visual observation methodWatch the flow direction During the normal operation of the clean workbench, the flow direction of the air can be observed through the transparent protective baffle. For the vertical unidirectional flow clean table, the air flow should be vertical and downward uniform flow; For the horizontal unidirectional flow clean table, the air flow is horizontal and smooth from one end to the other end. If the airflow is found to have a significant vortex, backflow, or disorder, it indicates that the airflow may be abnormal. For example, when operating in a vertical unidirectional flow clean workbench, gently place a thin strip of paper on the operating surface, the strip should be steadily pressed vertically. If the strip flutters, turns over, or moves diagonally, it may mean that the direction of the airflow is deviated or unstable. View the filter appearance. High high-efficiency filter is a key component that determines the quality of airflow. The access port (if allowed) can be opened to view the surface of the HEPA filter while the equipment is down and safe to do so. Under normal circumstances, the filter material should be clean, undamaged, and uniform in color. If it is found that there are obvious stains, holes, or uneven colors on the filter material (possibly because of moisture, pollution, and other reasons), this may affect the normal passage of the airflow, resulting in abnormal airflow. Second, the instrument detection method An anemometer detects wind speed. Wind speed is one of the important indicators to measure whether the airflow of a clean workbench is normal. The use of a professional anemometer can accurately measure the wind speed at different locations on the work table. For vertical unidirectional flow clean workbench, the average wind speed in the operating area is generally 0.3-0.5m /s; For horizontal unidirectional flow clean workbench, the average wind speed in the operating area is usually 0.4-0.6m /s. During detection, the probe of the anemometer is placed at different positions in the operating area, such as the four corners and the center position, and the wind speed at each position is recorded. If it is found that the wind speed at a certain location is significantly lower than the standard value or the wind speed difference is too large (for example, the difference between the maximum and minimum wind speed in the same operating area is more than 0.1m/s), it may indicate uneven air flow or abnormal fan operation. The differential gauge monitors the pressure difference. There is a certain pressure difference between the inside and outside of the clean workbench, which is the key to ensuring the one-way flow of air. This pressure difference can be monitored in real-time with a differential pressure meter. In general, the internal pressure of the clean workbench relative to the external environment should be maintained, and the pressure difference is usually about 2-5Pa. When the pressure difference displayed by the pressure differential meter is lower than the normal range, it may be caused by fan failure, filter blockage, or poor sealing, which will make the outside unfiltered air enter the operating area, thus affecting the normal circulation and cleanliness of the airflow. Third, the smoke test method Smoke generator test The use of a smoke generator to produce smoke is a more intuitive method of detecting airflow. Place the smoke generator near the air intake of the clean workbench, and observe the flow of smoke in the workroom after opening it. Under normal circumstances, the smoke should be evenly distributed with the direction of the airflow and be expelled quickly. If the smoke is stagnant, countercurrent, or can not be effectively discharged, such as smoke in a local area, or from the gap of the workbench and other places that should not overflow, this indicates that there is a problem with the airflow, which may be due to the blockage of the air channel, insufficient fan suction, or internal structural damage. When judging whether the airflow of the clean workbench is normal, the above methods need to be comprehensively used, and the specific use of the equipment and the previous detection data should be analyzed. If abnormal airflow is found, the equipment should be repaired and adjusted in time to ensure the performance of the clean workbench and the cleanliness of the operating environment. |
