The air velocity of the DOP transfer window is controlled in two scenarios, mainly based on the cleanliness level and functional positioning: the laminar flow surface air velocity is 0.36-0.54 m/s, and the air shower nozzle air velocity is ≥20 m/s.
Classification and control standards for wind speed
| Wind speed type | Control range | Applicable scenarios |
Basis and Requirements |
| Laminar flow surface wind speed | 0.36-0.54 m/s (commonly 0.4-0.5 m/s) | Self-cleaning DOP transfer window, high-efficiency filter air outlet | Meet ISO Class 5 cleanliness; JG/T 382-2012 requires ≥0.36 m/s and fluctuation ≤0.2 m/s |
| Air shower nozzle wind speed | ≥20 m/s (commonly 20-25 m/s) | DOP transfer window with air nozzle | According to JG/T 382-2012 and T/NAHIEN 111-2024, the central wind speed at the nozzle of the B3 type air shower transfer window shall not be less than 20 m/s |
Key points of control
Laminar flow surface air velocity: Measured by the average air velocity at the outlet of the high-efficiency filter, if it is too low, it will lead to a decrease in cleanliness; if it is too high, it is prone to turbulence and increased energy consumption. Regular detection is required and the filter element should be replaced when the resistance exceeds the standard.
Air shower nozzle wind speed: Ensure that high-speed airflow effectively removes dust from the surface of items. The measured wind speed at the center of each nozzle must meet the standard to avoid insufficient local wind speed affecting the air shower effect.
DOP leak detection correlation: Stable wind speed is the prerequisite for ensuring the accuracy of high-efficiency filter leak detection. Abnormal wind speed can cause distortion of the upstream dust concentration and downstream detection data. It is necessary to confirm that the wind speed is within the standard range before leak detection.
Measurement and Maintenance
Laminar flow surface wind speed: Evenly divide the air outlet into blocks (each block ≤ 100mm), measure the centroid wind speed of each block and take the average value. The fluctuation should be ≤ 0.2m /s.
Air velocity at the air shower nozzle: Measure the center of the nozzle with a hot sphere anemometer. The air velocity at all nozzles must be ≥20 m/s.
Maintenance cycle: Daily inspection is conducted once a day, and regular calibration is carried out once a month. After the filter element is replaced, the wind speed must be reconfirmed to meet the standards.
