The 6-point function of the fume hood is simply unparalleled

The main function of the fume hood is the exhaust function. In the chemical laboratory, various harmful gases, odors, moisture, and flammable, explosive, and corrosive substances are generated during experimental operations. In order to protect the safety of users, To prevent the pollutants in the experiment from spreading to the laboratory, fume hoods should be used near the pollution source. In the past, the number of fume hoods used was small, and they were only used in experiments with particularly harmful and dangerous gases and large amounts of heat. The fume hood is only responsible for the auxiliary functions of the experimental bench.

Fume hood application


In recent years, considering the improvement of the experimental environment, the experiments carried out on the experimental bench have gradually been transferred to the fume hood, which requires the fume hood to have functions suitable for the use of equipment. In particular, most newly-built laboratories require air-conditioning, so the number of fume hoods used must be included in the air-conditioning system plan in the preliminary design stage of the building. As fume hoods occupy a very important position in the biochemical laboratory, the number of fume hoods used has increased dramatically from the perspectives of improving the laboratory environment, improving labor sanitation conditions, and improving work efficiency. Following this is the ventilation ducts, piping, wiring, exhaust air, etc. have become important issues in laboratory construction.
The purpose of using the fume hood is to exhaust harmful gases generated in the experiment and protect the health of the experimenters. That is to say, it must have a high degree of safety and superior operability. This requires the fume hood to have the following functions:
(1) Release function: It should be equipped with a mechanism to absorb the harmful gas generated inside the fume hood by absorbing the gas outside the cabinet, dilute it and remove it outside.
(2) Non-reverse flow function: It should have the function of preventing harmful gas from flowing into the room from the inside of the fume hood by the airflow generated by the exhaust fan inside the fume hood. In order to ensure the realization of this function, it is a good way to connect a fume hood and a ventilator with a single pipe. It cannot be connected by a single pipe. It is limited to the same room on the same floor and can be connected in parallel. Install the ventilator as much as possible. At the end of the pipe (or at the top of the layer).
(3) Isolation function: In front of the fume hood, there should be a non-sliding glass window to separate the inside and outside of the fume hood.
(4) Supplementary function: It should have a passage or alternative device for sucking in air from outside the fume hood when discharging harmful gas.
(5) Wind speed control function: In order to prevent harmful gases from escaping in the fume hood, a certain suction speed is required. The factors that determine the suction speed of the air intake of the fume hood are: the heat generated by the experiment content and the relationship with the number of air changes. The main ones are the content of the experiment and the nature of the hazardous substance. It is usually stipulated that the general non-toxic pollutant is 0.25-0.38m/s, the toxic or dangerous harmful substance is 0.4-0.5m/s, the highly toxic or has a small amount of radioactivity is 0.5-0.6m/s, and the gas is 0.5m/s, granular material is 1m/s.
In order to ensure such a wind speed, the exhaust fan should have the necessary static pressure, that is, the frictional resistance when the air passes through the ventilation duct. When determining the wind speed, you must also pay attention to the noise problem. When the air flows in the pipe, the limit is 7-10m. Noise will be generated if the air is more than 10m. The noise limit value of the laboratory (indoor background noise level) is usually 70dBA. Lowering the wind speed also reduces the noise. Considering the cost and construction of the pipeline, the power of the pipeline and the exhaust fan must be carefully selected.
(6) Heat resistance and acid and alkali corrosion resistance: some electric furnaces must be installed in the fume hood, and some experiments produce a large amount of toxic and harmful gases such as acid and alkali, which are extremely corrosive. The countertops, liners, side panels, and the selected water nozzles and air nozzles of the fume hood should all have anti-corrosion function. Where strong acids such as sulfuric acid and nitric acid are used in the semiconductor industry or in corrosive experiments, the overall material of the fume hood must be acid-proof and must be made of stainless steel or PVC.