How to effectively control the wind speed of the surface of the laboratory fume hood
2022-08-27 02:03:31
With the development of science and technology and industrialization, the construction of laboratories in various fields has been fully carried out. Research institutes, industrial and mining enterprises, and majors generally have to set up laboratories for experimental research. The fume hood is the main safety device in the laboratory. In order to control the spillage of harmful substances and ensure the normal operation of the experiment, the wind speed of the cover must be effectively controlled. During the experiment, with the operation of the cabinet door, the opening area of ​​the fume hood changes, the wind speed of the cover surface changes greatly, and the ventilation system does not meet the design requirements, which affects the experiment and the effect of the exhaust.
During the test, the laboratory was accompanied by a large number of harmful substances such as gas, steam, dust and suspended particles, which caused serious damage to the health of the testers. Through the analysis of the performance of pipelines and fans in the ventilation system, the control system is designed to control the variable air volume of the ventilation cabinet ventilation system, and the wind speed of the system cover is basically stable. The system is worthy of popularization and application.
First of all. The fume hood is the main safety device in the laboratory. Most of the experiments are done in the fume hood. The fume hood is a special form of the hood, and the process of producing harmful substances is completely carried out in the hood. The fume hood generally has an openable and operable operation hole and an observation hole. By pumping the fume hood, a negative pressure is formed in the cabinet to prevent disturbance of mechanical equipment in the fume hood, chemical reaction or heat source heat source, and indoor lateral direction. The escape of harmful substances due to disturbances such as airflow.
Secondly, depending on the density of harmful gases and the density of air, there are many forms of fume hoods, and different types of fume hoods are used in different places. The main form of the fume hood includes: a fume hood with an upper exhaust, a fume hood with a lower exhaust, and a fume hood with a combined upper and lower exhaust. At the same time, there are energy-saving air supply fume hoods. Excessive wind speed on the cover can lead to airflow disorder in the space above the workbench in the fume hood. Contaminants may accumulate in a corner of the cabinet, and may blow out the flame, destroy the ongoing test, and the cover is too low. The wind speed will inevitably lead to the escape of pollutants and endanger the safety of testers. For toxic or dangerous hazardous materials, the wind speed of the fume hood operating mask surface is generally 0.4~0.5m/s.
The air volume of the fume hood is calculated according to formula (1) [1]: For the general laboratory fume hood, when considering the interference airflow in the room and the unevenness of the suction speed on the operating port of the fume hood, the opening area should be taken. A large opening area. It can be seen from the above formula that for the conventional fume hood without the adjustment system, when the operation door is fully opened, the cover wind speed of 0.4~0.5m/s can be satisfied, and when the operation door is opened half or fully closed, the operation surface is operated. The wind speed will be greater than the design value, which will affect the experimental operation and the effect of the exhaust. According to the actual test of a fume hood [2], when the door is fully opened, the wind speed of the cover is 0.47 m/s, and when the door is opened halfway, the wind speed of the cover is 0.86 m/s. When the door is nearly closed, the wind speed of the cover will be larger, which will greatly affect the exhaust and experimental results.
During the test, the laboratory was accompanied by a large number of harmful substances such as gas, steam, dust and suspended particles, which caused serious damage to the health of the testers. Through the analysis of the performance of pipelines and fans in the ventilation system, the control system is designed to control the variable air volume of the ventilation cabinet ventilation system, and the wind speed of the system cover is basically stable. The system is worthy of popularization and application.
First of all. The fume hood is the main safety device in the laboratory. Most of the experiments are done in the fume hood. The fume hood is a special form of the hood, and the process of producing harmful substances is completely carried out in the hood. The fume hood generally has an openable and operable operation hole and an observation hole. By pumping the fume hood, a negative pressure is formed in the cabinet to prevent disturbance of mechanical equipment in the fume hood, chemical reaction or heat source heat source, and indoor lateral direction. The escape of harmful substances due to disturbances such as airflow.
Secondly, depending on the density of harmful gases and the density of air, there are many forms of fume hoods, and different types of fume hoods are used in different places. The main form of the fume hood includes: a fume hood with an upper exhaust, a fume hood with a lower exhaust, and a fume hood with a combined upper and lower exhaust. At the same time, there are energy-saving air supply fume hoods. Excessive wind speed on the cover can lead to airflow disorder in the space above the workbench in the fume hood. Contaminants may accumulate in a corner of the cabinet, and may blow out the flame, destroy the ongoing test, and the cover is too low. The wind speed will inevitably lead to the escape of pollutants and endanger the safety of testers. For toxic or dangerous hazardous materials, the wind speed of the fume hood operating mask surface is generally 0.4~0.5m/s.
The air volume of the fume hood is calculated according to formula (1) [1]: For the general laboratory fume hood, when considering the interference airflow in the room and the unevenness of the suction speed on the operating port of the fume hood, the opening area should be taken. A large opening area. It can be seen from the above formula that for the conventional fume hood without the adjustment system, when the operation door is fully opened, the cover wind speed of 0.4~0.5m/s can be satisfied, and when the operation door is opened half or fully closed, the operation surface is operated. The wind speed will be greater than the design value, which will affect the experimental operation and the effect of the exhaust. According to the actual test of a fume hood [2], when the door is fully opened, the wind speed of the cover is 0.47 m/s, and when the door is opened halfway, the wind speed of the cover is 0.86 m/s. When the door is nearly closed, the wind speed of the cover will be larger, which will greatly affect the exhaust and experimental results.
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