When the all-steel fume hood is enabled and the operator stands in front of the fume hood and reaches into the fume hood to perform experimental operations, the airflow will form a rotating airflow around the operator, causing the gas in the cabinet to overflow and flow along the operator's body to the breathing area. The greater the inlet wind speed, the stronger the rotating airflow formed. In a relatively ideal operating environment, if the fume hood has good air flow suppression performance, the inlet wind speed can achieve air flow suppression at 0.3-0.41m/s, but the suppression performance will fluctuate within this range.
The inlet wind speed of the all-steel fume hood is 0.41-0.51m/s, and the air flow will also fluctuate. However, this wind speed is suitable for most laboratory chemical experiments, and laboratory operating specifications must still be strictly followed. There is little difference between the inlet wind speed in the range of 0.51-0.61m/s and the airflow in the range of 0.41-0.51m/s, but the operating cost will increase. Fume hood inlet wind speed can achieve airflow suppression within the range of 0.61-0.76m/s, but energy consumption will increase.
Therefore, if the all-steel fume hood location requirements and indoor ventilation frequency requirements are met, it is recommended that the inlet wind speed be greater than 0.3m/s, and 0.4-0.6m/s is suitable, which can better control the gas in the cabinet. The control device that controls the speed of the exhaust fan and the exhaust valve of the fume hood to adjust the exhaust volume of the fume hood should be reasonably designed. The exhaust volume should be 50cfm/ft*ft (width of the fume hood) or 25 cfm/ft2* ft2 (area of ​​the fume hood). If the fume hood is out of use or there are other requirements in the written hazard description, the appropriate exhaust volume should be selected according to the requirements.