Clean room of wind speed measurement method
clean room wind speed detection method
the most important factor of airflow is to control the cleanliness and temperature and humidity
1 is to control the cleanliness and airflow temperature and humidity of the most important factor, it also has some effect on noise. So the wind speed measurement, is on the first step of cleanroom testing. The purpose of wind speed measurement is confirmation screen out airflow meet the design specification, the second is confirm the airflow uniformity. In some cases may be due to the scene of the restrictions, indoor ventilation must also be corrected for wind speed multiplied by the export area to
single flow clean room, many of them are designed to be vertical laminar flow, wind speed evenness is important, therefore, only vertical laminar flow evenly, can effectively eliminate particle pollution. Not a single flow clean room, due to particle control idea is diluted, not immediately ruled out, in general the ventilation is far more important than speed. But should mark is mesh wind speed or clean room interior wind velocity measurement.
inside the clean room use HEPA/ULPA filter, its send out most of airflow speed control in 0. Within 5 m/s, so the use of anemometer type must be a low speed. Mesh wind measurements can be used single point anemometer, such as electronic pressure gauge with their tubes, hot-wire anemometer. Can also use the multi-point anemometer as Shortridge Velgrid anemometer 16 points. Wheel vane anemometer for use scope is different, generally does not use clean room. Hot-wire anemometer ( 热丝) Although the high frequency response is good, but when the low speed < 0. Under 5 m/s> accuracy is very low, so it's not very applicable, general thermal anemometer is Thermeister anemometer in common use. Propeller anemometer due to the weight itself, also is not applicable to low speed. Test instruments must be approved by calibration qualified, and is still in the valid period.
( 1) Recorded in figure surface mesh size, quantity, and numbered. ( 2) 75 - under the sampling points in the mesh 150 mm. ( 3) If each mesh, using single point anemometer, one per 1 square foot; If using multi-point anemometer, every 4 square feet take a little bit. ( 4) Each measurement point must take an average of 5 seconds. ( 5) All wind speed in accordance with the acceptance standard analysis, the calculation of mean, standard deviation and relative standard deviation, and indicate the unqualified test points. ( 6) Record all original value, and the numerical analysis after. Is important in a single flow clean room type test, pay special attention to when sampling anemometer is disturbed, lest affect accuracy.
4, data analysis,
wind speed measurement is very simple, but the uniformity must be determined by the data analysis. Evenness is represented by the relative standard deviation, the calculation steps are as follows.
1。 Average: 2. The standard deviation