Precautions for the use of laboratory fume hoods

Laboratory fume hood in use need to pay attention to, first of all, we should know that the use of fume hood in laboratory is to ensure the safety of users and prevent pollution of the surrounding environment, so safety is the greatest mission of the pursuit of fume hood. In the laboratory construction, we should choose a good fume hood and determine the installation position of the fume hood, need to consider the type, material and installation position of the fume hood according to the experimental use of drugs, environmental protection, energy saving and other content.

In a modern research laboratory, a qualified fume hood should have the functions of release, no backflow, isolation, supplement, heat resistance and acid and alkali corrosion resistance, and wind speed control. In use, attention should be paid to the correct use of fume hood. Before the start of the experiment, it must be confirmed that the fume hood should be in operation to carry out the experimental operation. During the experiment, the fume hood should have sufficient space, which should not affect the flow of air. The front window should be closed as far as possible. Before the end of the experiment, the ventilator should be closed for at least 5 minutes to discharge the residual gas in the pipeline. The installation position of the fume hood should avoid facing the road and the site where people pass frequently, avoid blocking Windows and unfavorable places for ventilation and lighting, avoid blocking the place where the entrance and exit affect the door switch, and avoid placing and placing in the corner wall. Advanced scientific instruments, perfect experimental equipment and good experimental environment are necessary conditions to improve the level of science and technology and promote scientific research results. People-oriented, ensure safety and improve efficiency are the biggest mission of laboratory construction. Fume hood as an important experimental facility in biochemical laboratory has a decisive role, so we must carefully choose the fume hood to meet the technical indicators. If there is any harm caused by ventilation cabinets installed in a unit that drives down the cost purely, the consequences would be unimaginable. People should pay enough attention to it.

1. Release function: It should have the harmful gas produced inside the fume hood by absorbing the gas outside the cabinet to dilute it and exclude the outdoor mechanism.

2. No backflow function: It should have the function that the harmful gas generated by the exhaust fan inside the fume hood does not reverse flow into the room from the inside of the fume hood. In order to ensure the realization of this function, a ventilator and a fan with a single pipe connection is the best method, can not use a single pipe connection, but also limited to the same floor and the same room can be connected, the fan as far as possible installed in the end of the pipeline (or the top of the layer).

3. Isolation function: non-sliding glass Windows should be used in front of the fume hood to separate the inside and outside of the fume hood.

4. Supplementary functions: there should be a channel or alternative device for inhaling air from outside the fume hood when the harmful gas is discharged.

5. Control the wind speed function: in order to prevent the escape of harmful gases in the fume hood, it is necessary to have a certain suction speed. The factors that determine the intake speed of the fume hood include: the heat generated by the experiment content and the relationship between it and the number of air changes. The main one is the content of the experiment and the nature of the harmful substance. Generally, the general non-toxic pollutants for 0.25-0.38m /s, toxic or dangerous harmful substances for 0.4-0.5m /s, highly toxic or a small amount of radioactivity for 0.5-0.6m /s, gas for 0.5m/s, granular matter for 1m/s. In order to ensure such wind speed, the exhaust fan should have the necessary static pressure, that is, the friction resistance of the air passing through the ventilation duct. When determining the wind speed, we must also pay attention to the noise problem. When the air flows through the pipeline, 7-10m is the limit, and noise will be generated if it exceeds 10m. Usually, the noise limit value of laboratory (indoor background noise level) is 70dBA Considering the cost and construction problems of pipeline, we must carefully choose the power of pipeline and exhaust fan.

6. Heat resistance and acid and alkali corrosion resistance: some experiments in the fume hood produce a large number of acid and alkali and other toxic and harmful gases with strong corrosion. The table top, lining plate, side plate and selected water nozzle, gas nozzle, etc. of the fume hood should have anti-corrosion function.