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    Home > Active Ingredient News > Drugs Articles > Selection and purchase of laboratory fume hood

    Selection and purchase of laboratory fume hood

    • Last Update: 2017-05-04
    • Source: Internet
    • Author: User
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    *Step: the main function of the fume hood the main function of the fume hood is the exhaust function In the chemical laboratory, various harmful gases, odor, moisture and flammable, explosive and corrosive substances are produced during the experimental operation In order to protect the safety of users and prevent the diffusion of pollutants in the experiment to the laboratory, fume hood should be used near the pollution source In the past, fume hood was used It can only be used in the experiments of especially harmful and dangerous gases and generating a lot of heat The fume hood is only responsible for the auxiliary function of the test bench In recent years, in order to improve the experimental environment, the experiments carried out on the experimental platform are gradually transferred to the fume hood, which requires that there should be Zui suitable for the use of equipment in the fume hood In particular, most new laboratories require air conditioning, because in the preliminary design stage of the building, it is necessary to include the number of ventilation cabinets in the air conditioning system plan As the fume hood occupies a very important position in the biochemical laboratory, the number of fume hoods has increased rapidly from the aspects of improving the laboratory environment, improving the labor and health conditions, and improving the working efficiency Then the ventilation pipe, piping, wiring, ventilation and so on have become important topics of laboratory building The main purpose of using the Zui of the fume hood is to exhaust the harmful gas produced in the experiment and protect the health of the experimenter, that is to say, it is necessary to have a high degree of safety and superior operability, which requires that the fume hood should have the following functions: 1 Release function: it should have a mechanism to absorb the harmful gas produced inside the fume hood by means of absorbing the gas outside the fume hood, so that it can be diluted and discharged out of the room 2 No backflow function: it has the function that the airflow generated by the exhaust fan in the fume hood will not flow the harmful body into the room from the inside of the fume hood In order to ensure the realization of this function, it is a good way for Zui to connect a fume hood with a fume hood by a single pipe It cannot be connected by a single pipe, and it is also limited to the same room on the same floor Install as far as possible at the end (or top) of the management 3 Isolation function: a non sliding glass window shall be provided in front of the fume hood to separate the inside and outside of the fume hood 4 Supplementary function: it shall have a channel or planning device for air intake outside the fume hood when harmful gas is discharged 5 Control wind speed function: in order to prevent the harmful gas in the fume hood from escaping, a certain suction speed is required Factors determining the suction speed of the fume hood: the heat generated by the experimental content and the relationship with the ventilation rate The main content of the experiment and the nature of harmful substances Generally, it is 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 extremely toxic or a small amount of radioactivity is 0.5-0.6m/s, the gaseous substance is 0.5m/s, and the granular substance is 1m / s In order to ensure such wind speed, the exhaust fan shall have necessary static pressure, that is, the friction resistance when air passes through the ventilation pipe When determining the wind speed, we must also pay attention to the noise problem When the air flows in the management, it is limited to 7-10m, and if it exceeds 10m, it will generate noise Generally, the noise limit value of the laboratory (indoor background noise level) is 70dba Increasing the management cutting area will reduce the wind speed, which will also reduce the noise Considering the management funds and construction problems, we must carefully select the power of the management and exhaust fan 6 Heat resistance and acid alkali corrosion resistance: some of the fume hoods need to be equipped with electric furnaces, and some of the experiments produce a large number of poisonous and harmful gases such as acid and alkali, which are highly corrosive The countertop, lining plate, side plate, water nozzle and air nozzle of the fume hood shall have anti-corrosion function When sulfuric acid, nitric acid, hydrofluoric acid and other strong acids are used in semiconductor industry or corrosive experiment, the overall material of the fume hood must be acid and alkali resistant, and it must be made of stainless steel or PVC material The second step is the classification of fume hoods Fume hoods are divided into three types: upper exhaust type, lower exhaust type and upper and lower exhaust type In order to ensure the uniform wind speed in the working area, the lower exhaust type is used for the ventilation cabinet in the cold process, the upper exhaust type is used for the ventilation cabinet in the hot process, and the upper and lower exhaust air ratio can be adjusted with the change of the heat in the cabinet for the unstable heat generation process, so as to obtain the uniform wind speed The fume hoods are also classified into three categories according to the way of air inlet It is called full exhaust type, which is a type of widely used When the ventilation cabinet is set in the room with heating or temperature and humidity control requirements, in order to save energy consumption of heating and air conditioning, the method of taking supply air from the outside and circulating in the cabinet and discharging it out of the outside is called supplementary air type ventilation cabinet Another is the VAV control type fume hood The common constant air volume system needs to manually adjust the air valve of fixed blades and the exhaust air volume of the fume hood When the valve is adjusted to a certain angle, the desired surface air speed can be achieved VAV control is to adjust the sensor of the valve to change the air volume to achieve the given face wind speed Of course, the standard type has low cost and high VAV cost, which is suitable for occasions requiring high precision The fume hood can be divided into integral lower open type, floor type, two side type, three side glass type, table type and one-piece type according to the use status, as well as the special fume hood designed for the radiation experiment, synthesis experiment and perchloric acid experiment according to the needs of different experiments The third step is to pay attention to the safety when using the fume hood Before the experiment, it must be confirmed that the fume hood should be in the running state before the experiment Before the end of the experiment, it is necessary to run for more than 5 minutes to close the ventilation, so as to discharge the residual gas in the pipeline It can also be considered to install exhaust time delay device to ensure delayed operation of ventilator During the experiment, no equipment shall be placed within 150 mm from the glass window Large experimental equipment shall have sufficient space and shall not affect the air flow The front window shall be closed for use in the daytime The fourth step is to select the fume hood in the laboratory construction, select the fume hood and determine the installation position of the fume hood It is necessary to select the type, material and shape of the fume hood according to the experimental content Generally, the following contents should be considered: Drugs used: when using organic substances or other special reagents for experiments, it is necessary to fully consider the control of wind speed, heat source: when using equipment with heat source, when the heat is more than 2000 kcal / h, it is necessary to consider the amount of ventilation required to exhaust the heat to determine the power of the ventilator When there is radioactive substance or chloric acid and other experiments: special ventilation cabinet shall be selected, and the air inlet speed must be set to be greater than 0.5m/s When using large-scale equipment for experiments: the effective size of the interior should be considered to leave necessary space for exhaust Material: when using special acid experiment, the material of fume hood should be considered, such as semiconductor industry, corrosion industry, etc must be made of anti-corrosion material Boundary dimension: select the boundary dimension according to the experimental content, too large volume will cause waste, too small impact on use Environmental protection: if the discharged harmful gas must be lower than the national environmental protection requirements, if it exceeds the national health standards, the corresponding purification device shall be installed Energy saving: energy saving shall be considered in the daytime In the room with heating or air conditioning, make-up type fume hood or fume hood with air volume control shall be adopted When selecting the fume hood, the power should also be determined according to the needs Do not blindly increase the exhaust air volume and pressure Use frequency converter or variable wind fan to reduce the power consumption In the installation position of the fume hood, it should be avoided to face the road and the site where people pass frequently, to block the windows and the places where the ventilation and lighting are unfavorable, to block the places where the entrance and exit affect the opening and closing of the door, and to avoid the opposite and rotation at the corner wall In a modern research laboratory, advanced scientific instruments, perfect experimental equipment and good experimental environment are the necessary conditions to improve the level of science and technology and promote scientific research achievements It is Zui's great mission of laboratory construction to make people-oriented, ensure safety and improve efficiency As an important experimental facility in biochemical laboratory, fume hood plays an important role Therefore, it is necessary to carefully select fume hood that meets various technical indexes, and ignore its functionality and safety If fume hood is installed in a unit with one-sided cost reduction, its consequences will be unimaginable, so people should pay enough attention to it 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! Suing Jinghua
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