Building a modern biochemical laboratory is a comprehensive system engineering. While equipping various instruments and supporting facilities, it is necessary to consider not only the requirements of power supply, water supply, drainage, air supply, exhaust air purification and sewage discharge, but also the safety, noise, and odor of personnel, objects, and surrounding environment , The comfort of the visual environment, the operability and functionality of the equipment, and the convenience of information processing. Therefore, the modern biochemical laboratory must have the best design and high-quality equipment to meet.
Among the modern laboratory equipment, there are fume hoods, central laboratory benches, side tables, medicine cabinets, utensil cabinets, gas cylinder cabinets, etc. Among them, fume hoods are very important functions in biochemical laboratory equipment and are indispensable equipment. . Therefore, choosing a fume hood is an important issue in the construction of a laboratory and must be given sufficient attention.
Main functions of fume hood
The most important function of the fume hood is the exhaust function. In the chemical laboratory, various harmful gases, odors, moisture, and flammable, explosive, and corrosive substances are generated during the experimental operation. In order to protect the safety of users To prevent the diffusion of pollutants in the experiment to the laboratory, a fume hood should be used near the source of the pollution. In the past, the number of fume hoods was small, and it was only used in experiments with particularly harmful and dangerous gases and large amounts of heat. The fume hood is only responsible for the auxiliary functions of the laboratory bench. In recent years, considering the improvement of the experimental environment, the experiments carried out on the experimental platform are gradually transferred to the fume hood, which requires the most suitable function of the equipment in the fume hood. In particular, most newly-built laboratories require air conditioning. Therefore, the number of fume hoods must be included in the plan of the air conditioning system during the preliminary design stage of the building. Because the fume hood occupies a very important position in the biochemical laboratory, the number of fume hoods used has increased dramatically in terms of improving the laboratory environment, improving labor conditions, and improving work efficiency. Along with it is the ventilation duct, piping, wiring, exhaust, etc. have become an important subject of laboratory construction.
The biggest purpose of using a fume hood is to exhaust the harmful gases generated in 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 the fume hood to have the following functions:
(1) Release function: It should be equipped with a mechanism to absorb the harmful gas generated inside the fume hood by absorbing the gas outside the cabinet, so that it can be diluted and excluded from the outdoor.
(2) Non-reverse flow function: it should have the function of the airflow generated by the exhaust fan inside the fume hood to prevent harmful gases from flowing into the room from the inside of the fume hood. In order to ensure the realization of this function, it is the best way to connect a fume hood to a fan with a single pipe. It cannot be connected with a single pipe, and it is only limited to the same room on the same floor. Installed at the end of the pipeline (or at the top of the floor).
(3) Isolation function: In front of the fume hood, a non-slip glass window should be used to separate the inside and outside of the fume hood.
(4) Supplementary function: It should have a passage or substitute device for sucking air from outside the fume hood when discharging harmful gases.
(5) Wind speed control function: To prevent harmful gas from escaping in the fume hood, a certain suction speed is required. The factors that determine the intake speed of the fume hood inlet air are: the heat generated by the experiment and the relationship with the number of ventilations. The main ones are the content of experiments and the nature of harmful substances. It is generally stipulated that the general non-toxic pollutants are 0.25-0.38m / s, the toxic or dangerous harmful substances are 0.4-0.5 m / s, the highly toxic or a small amount of radioactivity is 0.5-0.6m / s, and the gaseous substances are 0.5m / s, granular material is 1m / s. In order to ensure such a wind speed, the exhaust fan should have the necessary static pressure, that is, the frictional resistance of the air when passing through the ventilation duct. When determining the wind speed, you must also pay attention to the noise problem. When the air flows through the pipe, the limit is 7-10m, and more than 10m will produce noise. Usually the laboratory (indoor background noise level) noise limit is 70dBA. Reducing the wind speed will also reduce the noise. Considering the cost and construction of the pipeline, the power of the pipeline and the exhaust fan must be carefully selected.
(6) Heat resistance and acid and alkali corrosion resistance: Some of the fume hoods should be equipped with electric furnaces, and some experiments produce a large number of toxic and harmful gases such as acids and alkalis, which have strong corrosion. The countertop of the fume hood, the lining board, the side board and the selected water nozzle and gas nozzle should all have anti-corrosion function. The use of strong acids such as sulfuric acid, nitric acid, and hydrofluoric acid in the semiconductor industry or corrosive experiments also requires that the overall material of the fume hood must be acid and alkali resistant, and must be made of stainless steel or PVC.
Types of fume hoods
The fume hood is classified according to the exhaust method: it is divided into three types: upper exhaust type, lower exhaust type and upper and lower simultaneous exhaust type. In order to ensure uniform wind speed in the working area, the lower exhaust type should be used for the fume hood in the cold process, and the upper exhaust type should be used for the fume hood in the hot process. For the process with unstable heat generation, the exhaust vents can be provided at the upper and lower sides The change in the internal calorific value adjusts the ratio of the upper and lower exhaust air volume to obtain a uniform wind speed.
The fume hoods are classified into three categories according to the air intake method. After the indoor air is circulated in the cabinet and discharged outside, it is called the full exhaust type, which is a very widely used type.
When the fume hood is installed in a room with heating or temperature and humidity control requirements, in order to save heating and air conditioning energy consumption, the method of taking supplementary air from the outside and circulating it in the cabinet and exhausting it outdoors is called a supplementary fume hood.
The other is the variable air volume controlled fume hood. The ordinary constant air volume system needs to manually adjust the air valve of the fixed blade, adjust the exhaust volume of the fume hood, and achieve the desired surface wind speed when the valve is adjusted to a certain angle. Variable air volume control is to change the air volume to achieve a given surface wind speed by adjusting the sensor of the valve. Of course, the standard type has low cost and high variable air volume cost.
The fume hood can be divided into integral lower open type, floor type, two-sided type, three-sided glass type, tabletop type, one-piece type, and designed for different radioactive experiments and synthetic experiments , A special fume hood for perchloric acid experiments.
Among the modern laboratory equipment, there are fume hoods, central laboratory benches, side tables, medicine cabinets, utensil cabinets, gas cylinder cabinets, etc. Among them, fume hoods are very important functions in biochemical laboratory equipment and are indispensable equipment. . Therefore, choosing a fume hood is an important issue in the construction of a laboratory and must be given sufficient attention.
Main functions of fume hood
The most important function of the fume hood is the exhaust function. In the chemical laboratory, various harmful gases, odors, moisture, and flammable, explosive, and corrosive substances are generated during the experimental operation. In order to protect the safety of users To prevent the diffusion of pollutants in the experiment to the laboratory, a fume hood should be used near the source of the pollution. In the past, the number of fume hoods was small, and it was only used in experiments with particularly harmful and dangerous gases and large amounts of heat. The fume hood is only responsible for the auxiliary functions of the laboratory bench. In recent years, considering the improvement of the experimental environment, the experiments carried out on the experimental platform are gradually transferred to the fume hood, which requires the most suitable function of the equipment in the fume hood. In particular, most newly-built laboratories require air conditioning. Therefore, the number of fume hoods must be included in the plan of the air conditioning system during the preliminary design stage of the building. Because the fume hood occupies a very important position in the biochemical laboratory, the number of fume hoods used has increased dramatically in terms of improving the laboratory environment, improving labor conditions, and improving work efficiency. Along with it is the ventilation duct, piping, wiring, exhaust, etc. have become an important subject of laboratory construction.
The biggest purpose of using a fume hood is to exhaust the harmful gases generated in 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 the fume hood to have the following functions:
(1) Release function: It should be equipped with a mechanism to absorb the harmful gas generated inside the fume hood by absorbing the gas outside the cabinet, so that it can be diluted and excluded from the outdoor.
(2) Non-reverse flow function: it should have the function of the airflow generated by the exhaust fan inside the fume hood to prevent harmful gases from flowing into the room from the inside of the fume hood. In order to ensure the realization of this function, it is the best way to connect a fume hood to a fan with a single pipe. It cannot be connected with a single pipe, and it is only limited to the same room on the same floor. Installed at the end of the pipeline (or at the top of the floor).
(3) Isolation function: In front of the fume hood, a non-slip glass window should be used to separate the inside and outside of the fume hood.
(4) Supplementary function: It should have a passage or substitute device for sucking air from outside the fume hood when discharging harmful gases.
(5) Wind speed control function: To prevent harmful gas from escaping in the fume hood, a certain suction speed is required. The factors that determine the intake speed of the fume hood inlet air are: the heat generated by the experiment and the relationship with the number of ventilations. The main ones are the content of experiments and the nature of harmful substances. It is generally stipulated that the general non-toxic pollutants are 0.25-0.38m / s, the toxic or dangerous harmful substances are 0.4-0.5 m / s, the highly toxic or a small amount of radioactivity is 0.5-0.6m / s, and the gaseous substances are 0.5m / s, granular material is 1m / s. In order to ensure such a wind speed, the exhaust fan should have the necessary static pressure, that is, the frictional resistance of the air when passing through the ventilation duct. When determining the wind speed, you must also pay attention to the noise problem. When the air flows through the pipe, the limit is 7-10m, and more than 10m will produce noise. Usually the laboratory (indoor background noise level) noise limit is 70dBA. Reducing the wind speed will also reduce the noise. Considering the cost and construction of the pipeline, the power of the pipeline and the exhaust fan must be carefully selected.
(6) Heat resistance and acid and alkali corrosion resistance: Some of the fume hoods should be equipped with electric furnaces, and some experiments produce a large number of toxic and harmful gases such as acids and alkalis, which have strong corrosion. The countertop of the fume hood, the lining board, the side board and the selected water nozzle and gas nozzle should all have anti-corrosion function. The use of strong acids such as sulfuric acid, nitric acid, and hydrofluoric acid in the semiconductor industry or corrosive experiments also requires that the overall material of the fume hood must be acid and alkali resistant, and must be made of stainless steel or PVC.
Types of fume hoods
The fume hood is classified according to the exhaust method: it is divided into three types: upper exhaust type, lower exhaust type and upper and lower simultaneous exhaust type. In order to ensure uniform wind speed in the working area, the lower exhaust type should be used for the fume hood in the cold process, and the upper exhaust type should be used for the fume hood in the hot process. For the process with unstable heat generation, the exhaust vents can be provided at the upper and lower sides The change in the internal calorific value adjusts the ratio of the upper and lower exhaust air volume to obtain a uniform wind speed.
The fume hoods are classified into three categories according to the air intake method. After the indoor air is circulated in the cabinet and discharged outside, it is called the full exhaust type, which is a very widely used type.
When the fume hood is installed in a room with heating or temperature and humidity control requirements, in order to save heating and air conditioning energy consumption, the method of taking supplementary air from the outside and circulating it in the cabinet and exhausting it outdoors is called a supplementary fume hood.
The other is the variable air volume controlled fume hood. The ordinary constant air volume system needs to manually adjust the air valve of the fixed blade, adjust the exhaust volume of the fume hood, and achieve the desired surface wind speed when the valve is adjusted to a certain angle. Variable air volume control is to change the air volume to achieve a given surface wind speed by adjusting the sensor of the valve. Of course, the standard type has low cost and high variable air volume cost.
The fume hood can be divided into integral lower open type, floor type, two-sided type, three-sided glass type, tabletop type, one-piece type, and designed for different radioactive experiments and synthetic experiments , A special fume hood for perchloric acid experiments.
Fume hood safety
Safety is the biggest mission pursued by a fume hood. The use of a fume hood in a laboratory is to ensure the safety of users and prevent pollution of the surrounding environment.
Beijing Taiji Aofei Laboratory Equipment Co., Ltd. is one of the earliest professional companies in the development and production of fume hoods in China. Taiji Aofei Company has accumulated many years of experience and practice, combined with the characteristics of similar products at home and abroad, and gradually formed a fume hood technology as the center. Strength of laboratory equipment. While pursuing performance and function, Tai Chi Aofei's fume hood greatly considers its safety. These security is mainly reflected in
1. Adopting a single-slot exhaust structure to effectively discharge harmful gases.
2. The streamlined handle, there is a gap between the handle and the glass. Because the flow of air on the table is rotating, it ensures effective air intake from the surface.
3. Set the window anti-dropping pin. In case the glass window falls off the wire rope accidentally, the anti-dropping pin will catch it to prevent injury.
4. The glass window is made of tempered glass, even if the glass is accidentally broken or exploded, there will be no injury.
5. The upper part of the fume hood is provided with ventilation holes, even if the glass window is closed, air can be entered to avoid greater negative pressure.
6. The metal material of the fume hood shell is fireproof and non-combustible. The inner cavity is made of flame-retardant or non-combustible material such as anti-folding special plate, stainless steel plate, and the tabletop is made of solid core physical and chemical plate or stainless steel plate to prevent acid, alkali, heat and flame retardancy.
7. The effective height of the glass window is 800mm, the inner cavity is 1200mm, and the table height is 800mm. It is ergonomic, easy to operate, and has a large use space to improve safety.
8. The water nozzle and the gas nozzle are equipped with a remote operation handle outside the cabinet, which is more convenient and safe than direct manual operation.
When using the fume hood, you must also pay attention to safety
â—† Before the experiment starts, you must confirm that the fume hood should be in a running state before you can perform the experiment operation.
â—† Before the end of the experiment, it must continue to run for at least 5 minutes before turning off the ventilator to discharge the residual gas in the pipeline. It may also be considered to install an exhaust time delay device to ensure the delayed operation of the fan.
â—† During the experiment, do not put any equipment within 150mm from the glass window. Large-scale laboratory equipment should have sufficient space and should not affect the air flow.
Safety is the biggest mission pursued by a fume hood. The use of a fume hood in a laboratory is to ensure the safety of users and prevent pollution of the surrounding environment.
Beijing Taiji Aofei Laboratory Equipment Co., Ltd. is one of the earliest professional companies in the development and production of fume hoods in China. Taiji Aofei Company has accumulated many years of experience and practice, combined with the characteristics of similar products at home and abroad, and gradually formed a fume hood technology as the center. Strength of laboratory equipment. While pursuing performance and function, Tai Chi Aofei's fume hood greatly considers its safety. These security is mainly reflected in
1. Adopting a single-slot exhaust structure to effectively discharge harmful gases.
2. The streamlined handle, there is a gap between the handle and the glass. Because the flow of air on the table is rotating, it ensures effective air intake from the surface.
3. Set the window anti-dropping pin. In case the glass window falls off the wire rope accidentally, the anti-dropping pin will catch it to prevent injury.
4. The glass window is made of tempered glass, even if the glass is accidentally broken or exploded, there will be no injury.
5. The upper part of the fume hood is provided with ventilation holes, even if the glass window is closed, air can be entered to avoid greater negative pressure.
6. The metal material of the fume hood shell is fireproof and non-combustible. The inner cavity is made of flame-retardant or non-combustible material such as anti-folding special plate, stainless steel plate, and the tabletop is made of solid core physical and chemical plate or stainless steel plate to prevent acid, alkali, heat and flame retardancy.
7. The effective height of the glass window is 800mm, the inner cavity is 1200mm, and the table height is 800mm. It is ergonomic, easy to operate, and has a large use space to improve safety.
8. The water nozzle and the gas nozzle are equipped with a remote operation handle outside the cabinet, which is more convenient and safe than direct manual operation.
When using the fume hood, you must also pay attention to safety
â—† Before the experiment starts, you must confirm that the fume hood should be in a running state before you can perform the experiment operation.
â—† Before the end of the experiment, it must continue to run for at least 5 minutes before turning off the ventilator to discharge the residual gas in the pipeline. It may also be considered to install an exhaust time delay device to ensure the delayed operation of the fan.
â—† During the experiment, do not put any equipment within 150mm from the glass window. Large-scale laboratory equipment should have sufficient space and should not affect the air flow.
Selection of fume hood
When choosing a fume hood and determining the installation location of the fume hood during laboratory construction, it is necessary to choose the type, material, shape, etc. of the fume hood according to the experimental content, which is usually considered. The following:
Drugs used: When experimenting with organic substances or other special reagents, the wind speed should be fully considered. Heat source: When using equipment with a heat source, when the heat exceeds 2000 kcal / hour, the amount of ventilation required to discharge the heat should be considered to determine the power of the fan.
When there are experiments with radioactive materials or perchloric acid, etc .: a special fume hood should be selected, and the air velocity of the inlet air must be set to be greater than 0.5m / s.
When experimenting with large equipment: consider the effective size of the interior and leave the necessary space for exhaust.
Material: When using special acid experiments, the material of the fume hood should be considered. For example, the semiconductor industry and the corrosion industry must be made of anti-corrosion materials.
Overall dimensions: Select the overall dimensions according to the experimental content. Too large a volume will cause waste, and too small will affect the use.
Environmental protection: if the harmful gas discharged must be lower than the national environmental protection requirements, if it exceeds the national
When choosing a fume hood and determining the installation location of the fume hood during laboratory construction, it is necessary to choose the type, material, shape, etc. of the fume hood according to the experimental content, which is usually considered. The following:
Drugs used: When experimenting with organic substances or other special reagents, the wind speed should be fully considered. Heat source: When using equipment with a heat source, when the heat exceeds 2000 kcal / hour, the amount of ventilation required to discharge the heat should be considered to determine the power of the fan.
When there are experiments with radioactive materials or perchloric acid, etc .: a special fume hood should be selected, and the air velocity of the inlet air must be set to be greater than 0.5m / s.
When experimenting with large equipment: consider the effective size of the interior and leave the necessary space for exhaust.
Material: When using special acid experiments, the material of the fume hood should be considered. For example, the semiconductor industry and the corrosion industry must be made of anti-corrosion materials.
Overall dimensions: Select the overall dimensions according to the experimental content. Too large a volume will cause waste, and too small will affect the use.
Environmental protection: if the harmful gas discharged must be lower than the national environmental protection requirements, if it exceeds the national
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