Design scheme of ventilation cabinet system in biological laboratory

1 The main function of the fume hood and the application of the fume hood Zui is to control all kinds of harmful gases, water vapor, odor, waste heat, etc produced during the experimental operation in the fume hood side by side, so as to protect the safety of users and prevent the pollutants in the experiment from spreading to the laboratory The fume hood is widely used in various biochemical and physicochemical laboratories It plays an important role in protecting the purity of the experimental samples, ensuring the accuracy of the experimental results, maintaining the cleanness of the laboratory environment, improving the working conditions and efficiency The fume hood can be used in physical and chemical laboratory, biological laboratory and clean laboratory, but it is not suitable for Biosafety Level III and level IV laboratories 2 The performance of fume hood is usually measured by three parameters: catching efficiency, restraining efficiency and eliminating harmful gas efficiency Good capture efficiency can be obtained through two ways: first, to maintain the reasonable face wind speed of the ventilation cabinet opening, and second, to arrange the ventilation cabinet reasonably A reasonable design of the cabinet body and a reasonable face wind speed of the opening of the cabinet are the key to obtain a high suppression efficiency The efficiency of removing harmful gases is achieved by the height of the outdoor outlet and the appropriate wind speed 2.1 design principle: the number of fume hoods in the workplace depends on the type of experimental research, and there are great differences Generally, in research institutes and universities, one fume hood is set for each researcher in Chemistry Research Laboratory, one fume hood is shared by 6-10 researchers in biology research laboratory, and one fume hood is set for the whole department in physics laboratory The type of fume hood should be selected and the number of fume hood should be determined according to the experimental properties and the technological requirements of the laboratory Considering various factors comprehensively, determine the form of exhaust system and make-up air system of the fume hood, and determine the position of the fume hood and the fume shaft Based on the principle of safety, practicality, effectiveness and economy, the harmful gas shall be discharged as soon as possible and nearby, without polluting the environment and operators, and the gaseous pollutants in the experiment shall be controlled within the ventilation cabinet The position of the fume hood in the laboratory should be reasonably determined in combination with the technology and construction disciplines The fume hood shall be set in the place with less interference of air flow, far away from the door, air supply outlet and frequent passage of personnel, to avoid the interference of unorganized air flow to the fume hood exhaust flow field; at the same time, it shall also be far away from precision instruments, to avoid the fume hood exhaust affecting instrument operation According to bs7258 standard, when the fume hood is parallel to the through air, its front end shall be 1 m away from the door edge; when the fume hood is perpendicular to the through air, its near end shall be 1 m away from the door edge, and the clear distance between the fume hood arranged in opposite direction shall be 3 m According to the environmental impact assessment report of the construction project and its approval opinions, as well as the composition of the polluted gas, the waste gas treatment measures to be taken shall be determined, the treatment equipment shall be selected, and the requirements for the setting of the discharge outlet shall be met The following factors shall be considered in the selection and layout of exhaust fan: (1) first, the material of exhaust fan shall be corrosion-resistant Generally, centrifugal fan shall be selected to place the motor outside the exhaust gas (2) Considering the possibility of construction and laboratory changes in the future, certain margin shall be considered for the air volume and pressure head of the fan (3) In order to reduce noise and vibration, the speed of the fan shall not be higher than 1450r / min The installation position of the fan shall be reasonably determined, and the following factors shall be taken into consideration: ① due to the noise and vibration of the fan, the installation location shall be far away from the room where the noise and vibration are limited as far as possible, and shall be relatively centralized; it is convenient for installation and maintenance ② The fan shall be arranged in the machine room as much as possible, especially in cold and cold areas, which is convenient for sound insulation and vibration reduction, and also for anti freezing ③ The exhaust fan shall be arranged near the discharge outlet as far as possible, such as the top floor or roof, so as to maintain the negative pressure of the indoor exhaust pipe, and avoid the adverse effect of air leakage on other rooms through which the air pipe passes ④ Determine the control mode of exhaust system and make-up air system of the fume hood Air conditioning room should consider room pressure control and be combined with the building control system of the whole experimental building 2.2 system design 2.2.1 at present, there are no standards and specifications in China for the determination of the face wind speed of the ventilation cabinet The engineering design is usually determined according to the recommended value of the design manual or the requirements of Party A and the process 2.2.2 in general, a variety of reagents are used in physical and chemical experiments of waste gas treatment The exhaust gas composition of the fume hood is complex and variable, and the concentration of harmful substances is not high, so it can be discharged directly Only in some special cases need to exhaust (1) When high concentration strong acid and strong alkali are widely used in the experiment, the exhaust gas purification tower can be used to treat the exhaust air based on the principle of acid-base neutralization (2) When radioactive nuclear elements are used in the experiment, the exhaust air shall be treated by air filter before discharging (3) When ammonia or test products are used in the experiment, which contain ammonia, odor or trace carcinogens, the exhaust air shall be filtered by active carbon and then discharged Granular activated carbon should be selected for adsorption of gaseous substances, and its carbon tetrachloride activity should be higher than 60% (4) When marking test is conducted in the fume hood, the air outlet shall be equipped with iodine removal filter device (5) When the fume hood is tested for mercury content, the air outlet shall be equipped with potassium permanganate and sodium hypochlorite solution absorption device or sulfur loaded activated carbon for absorption and discharge 2.2.3 the features of the ventilation system shared by the ventilation cabinet and the room are as follows: (1) the frequency converter is directly controlled by the displacement sensor, and no sensor is installed in the air duct, which avoids the sensor from corrosion and pollution, and realizes the VAV control at a lower cost (2) The exhaust air volume is directly adjusted through the lifting of the glass door, and the control is simple (3) The energy saving effect is good When the air volume is small, it can not only save power, but also reduce the loss of cold and heat (4) When exhaust air at low speed, the indoor and outdoor noise is reduced (5) When the ventilation cabinet door is half open and full open, the surface wind speed is about 0.5m/s, when the opening height of the cabinet door is less than 300mil, the surface wind speed is about 1m / s, and the wind speed increases The surface wind speed is not stable Shanghai Sujing Industry Co., Ltd if you have any need, you can pass with us at any time Thank you very much for your support and look forward to cooperating with you Thank you & bestragard! 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