Function of fume hood
Release time:2018-08-13
The most important function of the fume hood is the exhaust function. In the chemical laboratory, various harmful gases, odors, humidity, flammable, explosive and corrosive substances are produced during the experimental operation. In order to protect the safety of users and prevent the pollutants from spreading to the laboratory, the fume hood should be used near the pollution source. In the past, the number of ventilators used was small, only used in particularly harmful and dangerous gases and generate a large number of heat experiments. The fume hood only takes on the auxiliary function of the test bench. Considering the improvement of the experimental environment, the experiments carried out on the test bench are gradually transferred to the fume hood, which requires that the fume hood should have the most suitable function for the use of equipment. In particular, most of the new laboratories are required to have air conditioning, so in the preliminary design stage of the building will be the use of the number of ventilators into the air conditioning system plan. As the fume hood occupies a very important position in the biochemical laboratory, the number of fume hood used has increased by leaps and bounds considering the improvement of laboratory environment, labor hygiene conditions and work efficiency. Following is the ventilation duct, piping, wiring, ventilation and so on have become an important topic of laboratory construction.
The greatest purpose of using a fume hood is to discharge harmful gases from the experiment and protect the health of the experimenters, that is to say, to have a high degree of safety and superior operability, which requires that the fume hood should have the following functions:
(1) Release function: the harmful gas produced inside the fume hood should be absorbed by the way of outside the fume hood so that it can be diluted and removed from the outside.
(2) Non-reflux function: It should have the function that harmful gas does not flow into the room from the inside of the fume hood by the air flow generated by the exhaust fan in the fume hood. To ensure that this function is achieved, a single pipe connection between a hood and a fan is the best way to connect a single pipe, not a single pipe connection, but also limited to the same floor in the same room can be connected in parallel, ventilators as far as possible in the end of the pipe (or top).
(3) Isolation function: in front of the fume hood should have non-sliding glass windows to separate the inside and outside of the fume hood.
(4) Supplementary function: It should have a passage or alternative device for inhaling air from the outside of the fume hood when discharging harmful gas.
(5) Control of wind speed function: in order to prevent harmful gases from escaping from the fume hood, it is necessary to have a certain inhalation speed. The factors that determine the intake speed of the fume hood are: the heat generated by the experimental content and the relationship with the number of ventilation. The main contents are the contents of the experiment and the nature of the harmful substances.
(6) Heat-resistant and acid-alkali corrosion resistance: some of the fume hood to be installed in the electric furnace, and some experiments produce a large number of toxic and harmful gases such as acid and alkali with strong corrosiveness. Fume cabinet countertop, liner, side board and selected nozzle, air nozzle, etc. should have anti-corrosion function. In the semiconductor industry or corrosive experiments using sulfuric acid, nitric acid, hydrofluoric acid and other strong acid occasions also require that the overall material of the hood must be acid and alkali-proof, must be made of stainless steel or PVC materials.
