In chemistry experiments, often produce a variety of unpleasant, corrosive, toxic or explosive gases. These harmful gases such as not timely exclude outdoors, should cause indoor air pollution, affecting the health and safety of laboratory personnel; precision and lifetime effects of equipment, so the design lab laboratory ventilation is an indispensable component. In order to make laboratory workers inhaled or swallowed some of the non-toxic, can be pathogenic or toxic unknown chemicals and organisms, the laboratory should have good ventilation. To prevent some of the vapor, gases and particulates (smoke, soot, dust and gas hanging body) inhaled pollutants have to use a fume hood, hood, local exhaust removed.

 

Chemical laboratory ventilation in two ways, namely local exhaust ventilation and the whole room. Local exhaust is discharged immediately after the nearest hazardous substances, in this way at a small amount of wind to drain away a lot of harmful substances, energy province and effect is to improve the existing laboratory conditions feasible and economical method, it may It is the best way to adapt to the new laboratory building ventilation. For some experiments can not use local exhaust, or local exhaust ventilation can not meet the requirements, the full room ventilation.

 

Laboratory fume hood is most commonly used as a local ventilation equipment, his performance is good or bad depends on the velocity of the air moving through the fume hood. Factors affecting the front velocity and air movement is a vortex, inlet shape cabinet thermal load, mechanical action, ventilation hole design and anti-coagulant and the like. In addition, still in his fire resistance, corrosion resistance, is easy to collect before entering the ventilation system capacity and other properties of some pollutants and contaminants related to cleaning. Generally believed that the laboratory fume hood should be able to adapt to flammable liquids and gases, and structural materials should have a few minutes of fire resistance, in order to maintain the integrity and the fume hood closed promptly put out the fire.

 

Exhaust systems

 

Fume hood exhaust system can be divided into two kinds of centralized and decentralized.

 

Centralized floor is one or more layers of the fume hood floor of the formation of a system, or the entire laboratory building is divided into twelve systems. It is characterized by a small fan, equipment investment, but also a slight increase or decrease the number of the fume hood, and change the location, have a certain flexibility. However, due to the larger system, air flow is not easy to balance, although air-control valve on each fume hood, but inconvenient to use, and is not easy to achieve the desired effect. If the system needs an overhaul duct is damaged, then the whole system of the fume hood can not be used. Therefore, the original system of centralized laboratory, has all changed with the decentralized system.

 

It is distributed to a fume hood or with several rooms to form a fume hood exhaust systems. His features are: According to the work required to open and close the fume hood fan, mutual overlooked, easy to achieve the desired effect, and the ratio of centralized to save energy, because the centralized system, as long as the use of a fume hood, you have to start big fan. Because of the small distributed systems, exhaust volume is small, the resistance is small, so the air volume fan, air pressure is not large, impatient sound and vibration is correspondingly smaller.