The biochemical laboratory modernized by the laboratory construction management method is a comprehensive system engineering. While equipped with various instruments and equipment and its supporting facilities, it is necessary to consider the requirements of power supply, water supply, drainage, air supply, exhaust air purification and sewage discharge, and also consider the safety, noise and odor of people, objects and surrounding environment. The comfort of the visual environment, the operability and functionality of the equipment, and the convenience of information processing. Therefore, modern biochemical rooms must have good design and high quality equipment to meet.
Among the modern equipments, there are central test benches, side platforms, medicine cabinets, utensil cabinets, gas cylinder cabinets, etc., among which biochemical room equipment plays an important role and is an indispensable equipment. Therefore, choice is an important issue in construction and must be given enough attention.
The main functions of the laboratory fume hood:
The main function is the exhaust function. In the chemical room, various harmful gases, odors, moisture and flammable, explosive and corrosive substances are generated during the experimental operation. In order to protect the safety of the user, the experiment is prevented. Contaminants are diffused and used near the source of pollution. In the past, the number of used substances was small, and it was only used in experiments where particularly harmful and dangerous gases and large amounts of heat were generated. Only bear the auxiliary function of the experimental bench.
In recent years, considering the improvement of the experimental environment, the experiments carried out on the experimental bench have gradually shifted to the inside, which requires the function to be suitable for the use of the device. In particular, most of the new construction requires air conditioning, so the number of units to be used in the preliminary design stage of the building is included in the air conditioning system plan. Due to the very important position in the biochemical room, the number of users has increased dramatically in terms of improving the environment, improving labor hygiene conditions, and improving work efficiency. Along with the ventilation ducts, piping, wiring, and exhaust are all important issues in construction.
The main purpose of the use is to discharge the harmful gases generated in the experiment and protect the health of the experimental personnel, that is to say, to have a high degree of safety and superior operability, which requires the following functions:
(1) Release function: It is necessary to use a method of diluting the harmful gases generated inside into the outside of the cabinet and diluting them to exclude the outside.
(2) Non-backflow function: It should have the function of internally generating air from the exhaust fan to prevent harmful gas from flowing into the room from the inside. In order to ensure the realization of this function, it is a good method to connect a single fan to a single fan. It cannot be connected by a single pipe. It is also limited to the same room in the same floor. The fan can be installed in the pipe as much as possible. The end of the layer (or at the top of the layer).
(3) Isolation function: The inside and outside should be separated by a glass window that does not slide in the front.
(4) Supplementary function: There should be a passage or an alternative device for taking in air from the outside when harmful gases are exhausted.
(5) Control of wind speed function: In order to prevent the escape of harmful gases, a certain suction speed is required. The factors that determine the rate of inhalation of the incoming air are: the amount of heat generated by the experimental content and the number of times of ventilation. The main ones are the experimental content and the nature of the harmful substances. Generally, the generally non-toxic pollutants are 0.25-0.38 m/s, the toxic or dangerous pollutants are 0.4-0.5 m/s, highly toxic or a small amount of radioactivity is 0.5-0.6 m/s, and the gas is 0.5m/s, granules are 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 as it passes through the ventilation duct. When determining the wind speed, you must also pay attention to the noise problem. When the air flows through the pipeline, it is limited to 7-10m. If it exceeds 10m, noise will be generated. Usually, the noise limit of the indoor background noise level is 70dBA. Increasing the cut area of the pipeline will reduce the wind speed. It also reduces noise. Considering the cost of the pipeline and construction problems, the power of the pipeline and the exhaust fan must be carefully selected.
(6) Heat resistance and acid and alkali corrosion resistance: Some of them have electric furnaces to be placed, and some experiments produce a large amount of toxic and harmful gases such as acid and alkali, which are extremely corrosive. The countertops, linings, side panels and selected water nozzles and air nozzles shall have anti-corrosion functions. In the semiconductor industry or in corrosive experiments, the use of strong acids such as sulfuric acid, nitric acid, hydrofluoric acid, etc., requires that the overall material must be acid and alkali resistant and must be made of stainless steel or PVC.
The categories selected for the fume hood are classified according to the way of exhaust: they are divided into the upper exhaust type, the lower exhaust type, and the upper and lower simultaneous exhaust type. The wind speed in the work area is uniform. For the cold process, the lower exhaust type should be used. For the hot process, the upper exhaust type is adopted. For the process of unstable heat generation, the exhaust port can be adjusted with the change of the heat generated in the cabinet. The ratio of the amount of air discharged above and below to obtain a uniform wind speed.
According to the way of entering the wind, there are also three categories. It is called a full exhaust type by circulating indoor air in the cabinet and then discharging it. This is a very widely used type.
When it is installed in a room with heating or control requirements for temperature and humidity, in order to save heating and air conditioning energy consumption, the method of exhausting air from the outside and circulating it in the cabinet and then discharging it outside is called the supplemental air type.
The other is variable air volume control. The ordinary constant air volume system needs to manually adjust the damper of the fixed blade, adjust the exhaust air volume, and achieve the desired surface wind speed when the valve is adjusted to a certain angle. The variable air volume control is to change the air volume by adjusting the sensor of the valve to achieve a given surface wind speed. Of course, the standard type has low cost and high variable air volume cost, and is suitable for occasions requiring high precision.
According to the state of use classification can be divided into the overall lower open, floor-standing, two-sided, three-sided glass, desktop, conjoined and designed according to the needs of different experiments for the radioactive experiments, the synthesis of experiments, Dedicated to perchloric acid experiments.
Safety is the mission of the pursuit, the use is to the safety of users and to prevent pollution of the surrounding environment.