What should be paid attention to in the application of fume hoods?
Fume hoods are an essential part of laboratory furniture. It plays the role of exhaust and ventilation in the laboratory. Various harmful gases, odors, moisture and flammable, explosive and corrosive substances will be generated during the experimental operation. In order to ensure the safety of users and prevent the pollutants during the experiment from spreading to the laboratory To use a fume hood, the number of fume hoods used in the past is small, and it is only used during experiments that generate particularly harmful and dangerous gases and generate a lot of heat. The fume hood only bears the auxiliary function of the laboratory bench.
Fume hoods are classified according to the way of exhaust: upper exhaust, lower exhaust and upper and lower simultaneous exhaust. In order to ensure uniform wind speed in the working area, the experimental fume hood for the cold process should adopt the lower exhaust type, and the experimental fume hood for the hot process adopts the upper exhaust type. The exhaust port adjusts the ratio of the upper and lower exhaust air volume according to the change of the calorific value in the fume hood, and finally obtains a uniform wind speed. Fume hoods are also divided into three categories according to the different air intake methods. It is called the full exhaust type, which circulates through the indoor air into the cabinet and then discharges it outdoors, which is also the most widely used type.
The fume hood should pay attention to safety during use. Before the experiment starts, it must be confirmed that the fume hood is in operation before the experimental operation can be carried out. Before the end of the experiment, it is necessary to continue to run for at least 5 minutes before turning off the ventilator, so as to discharge the residual gas in the pipeline. It is also possible to consider installing an exhaust time delay device to ensure that the fan runs in a delayed manner. During the experiment, do not place any equipment within 150mm of the glass window. Large laboratory equipment should have sufficient space to not affect the flow of air. The front window should be closed as much as possible.