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What are clean rooms, cleanliness, and local space purification?
What are clean rooms, cleanliness, and local space purification?Answer: Clean rooms refer to rooms and areas that require environmental control for dust particles and microbial contamination.Local space purification refers to only making the concentration of suspended particles in a specific local space of the indoor working area reach the specified air cleanliness level. Cleanliness refers to the number of suspended particles per unit volume of air in a clean environment that is greater than or equal to a certain allowable statistical number. What are the two test states of filters? Test methods for air filters and test methods for filter efficiency? Answer: The test states of filters are: dynamic test and static test. Test methods for filters are the sodium flame method and oil mist method. Test methods for filter efficiency are the atmospheric dust test method and artificial dust test method. What is dust concentration? How to sample in a clean room (area) and how to evenly arrange the sampling points? How to determine the level of a clean room (area)? Answer: It refers to the number or mass of suspended particles contained in a unit volume of air. When the unit is expressed in "particles/liter", it is called counting concentration: when the unit is expressed in mg/m3, it is called weight concentration. When sampling in a clean room, the sampling locations should be evenly arranged on a horizontal plane 0.8m above the ground. If there are more than 5 points, they can also be arranged in layers in an area of 0.8m~1.5m above the ground. The air supply volume and pressure difference should be determined during sampling, and the return air outlet should be avoided. The sampling points in the clean room should be arranged evenly to avoid sparse sampling points in a certain local area. The clean room grade is determined based on the following two conditions: The average particle concentration of each sampling point must be lower than or equal to the specified level limit, that is, Ai≤level limit. The 95% confidence limit of the mean of the average particle concentration of all sampling points must be lower than or equal to the specified level limit, that is, UCL≤level limit. What are the principles for expressing the external dimensions of air filters and the appearance requirements? Answer: The principles for expressing the external dimensions of air filters are: the depth is the direction of airflow, the vertical length is the height when the vertical plane of the airflow direction is correctly installed, and the horizontal length is the width. How are air filters classified according to performance (type, filter material replacement method)? Answer: According to the type, they are classified into flat type, pleated type, bag type, and winding type; according to the replacement method of the filter material, they are divided into washable, cleanable, and disposable. What are the principles and basis for customers to judge whether the air filter (primary, medium, and high-efficiency filter) is qualified? Answer: For a sample, if one of the main items or two of the other items in the inspection items are unqualified, the sample is unqualified; If one of the samples is unqualified during the inspection, double the sampling. If there is still one unqualified, the batch of filters is unqualified; If more than 3 (including 3) filters have the same defect, the entire batch of products is also unqualified. What issues should be paid attention to during the labeling, packaging, and transportation of air filters? Answer: Label: Each filter must be marked in a conspicuous position. If necessary, the airflow direction should also be indicated. The content of the marking should at least include the product name, filter model specification, efficiency at rated air volume and initial resistance, manufacturer name, and product production date. Packaging: The packaging should be able to protect the filter that has passed the factory inspection from damage caused by external factors during loading and unloading, transportation, handling, storage, and before installation by the user. Before packaging, the filter should be placed in a plastic bag and protected with a hard board of the same size as the end face at both ends. Transportation: During the transportation of the filter, place it according to the mark on the package and take fixed measures to stack it at a high height to avoid crushing. Determination of the counting efficiency of atmospheric dust particle size grouping? Answer: Underrated air volume, two dust particle counters are generally used to simultaneously measure the particle count concentration of particles greater than or equal to 0.5um, greater than or equal to 1.0um, greater than or equal to 3.0um, and greater than or equal to 5um in the air on the upper and lower wind sides of the test filter to group them. What are the conditions of temperature, humidity, and pressure insertion during clean room testing? Answer: The temperature and relative humidity of the clean room area should be consistent with its production process requirements. The temperature is controlled between 18°C and 24°C. Its relative humidity is 45%~%; the pressure difference is generally a relatively positive pressure, and the pressure difference between clean rooms with different air cleanliness should be ≤4.9Pa. How about the fan of the duct system (fan, air pressure, resistance of the air inlet filter)? Answer: The air volume of the fan of the duct system is generally calculated by 1.3 times the test air volume of the tested filter; the resistance of the duct is generally calculated by 1.2 times the calculated resistance, and the resistance of the air inlet filter is calculated by 2 times the initial resistance; the rated air volume and wind speed of the tested filter must be ensured to ensure that the installation frame of the tested filter leaks, otherwise it will affect the accuracy of the data. What are the units of wind speed, resistance, rated air volume, initial resistance, final resistance, and filtration efficiency of the air filter? Answer: The wind speed of the air filter is expressed in "m/s", the air volume is expressed in "m/h3", the resistance, initial resistance, and final resistance are expressed in "Pa", the filtration efficiency is expressed in "%MPPS", and the dust particles are expressed in microns um. |
