In the control of clean room environment, the air volume hood serves as the core equipment for accurately measuring the air volume of the air supply, return, and exhaust ports. Its data accuracy directly affects the cleanliness level and production safety. Mastering scientific testing methods and maintenance techniques is a key step in ensuring the stable operation of cleanrooms.
1、 Standardize the testing process
Before testing, three core preparations need to be made: first, equipment calibration. According to JJF1658-2017 "Wind Cover Calibration Specification", professional calibration should be conducted at least once a year to ensure that the errors of components such as wind speed sensors and differential pressure transmitters are within ± 3%; The second is environmental inspection. Close non essential equipment in the clean room and wait for the temperature and humidity to stabilize (temperature 20-24 ℃, relative humidity 45% -65%). Clean the obstacles around the air outlet to avoid airflow disturbance; The third step is equipment debugging. Fit the cover to the air vent, check the sealing of the sealing ring, preheat the equipment for 15 minutes, and start testing after the display screen data stabilizes.
The testing operation should follow the "three-point measurement method": stay at the left, middle, and right positions of the same air outlet for 30 seconds, record the instantaneous air volume value, and take the average of the three measurements as the final result. If the test data fluctuates by more than 5%, it is necessary to investigate whether there are problems such as air leakage from the cover, blocked air vents, or unstable fan pressure. For efficient air supply outlets, it is also necessary to synchronously detect the uniformity of air flow to ensure that the deviation of air velocity at the outlet section does not exceed ± 15%.
2、 Staged maintenance management strategy
（1） Daily maintenance (after daily use)
Appearance cleaning: Use a dust-free cloth dipped in 75% medical alcohol to wipe the surface of the hood and the wind speed sensor to avoid dust accumulation affecting detection accuracy;
Sealing inspection: Press the sealing ring of the cover body. If there is deformation, cracking or decreased elasticity, replace the silicone sealing ring of the same specification in a timely manner;
Data verification: Compare the test data of the day with the historical mean. If the deviation exceeds 10%, the machine must be immediately shut down for re calibration.
（2） Regular maintenance (quarterly)
Internal maintenance: Remove the side cover of the equipment, clean the circuit board and sensor dust with compressed air (pressure ≤ 0.3MPa), and check whether the wiring terminals are loose;
Performance verification: Use a standard wind tunnel to calibrate the span of the airflow hood, ensuring that the measurement error within the rated airflow range (such as 0-5000m ³/h) meets the requirements;
Accessory replacement: If the display screen is found to be aging, the buttons are malfunctioning, or the battery life is reduced, replace the original accessories in a timely manner to avoid testing interruption caused by equipment failure.
3、 Verification and recording after maintenance
After each maintenance or calibration, 3-5 typical air vents should be selected in the clean room for repeated testing to verify the consistency of air volume data. At the same time, establish a complete equipment file, detailing the testing date, maintenance content, calibration results, and operators to ensure traceability. In addition, it is recommended to conduct a comprehensive evaluation of the airflow balance in the cleanroom every six months, adjust the supply and return air ratio based on the airflow hood test data, and ensure the continuous stability of the clean environment.