The construction of a modern biochemical laboratory is a comprehensive system project. While equipped with various instruments and equipment and its supporting facilities, it is necessary to consider not only the requirements for power supply, water supply, drainage, air supply, and exhaust purification, but also the safety of personnel, objects, and the surrounding environment, noise, and odor. , the comfort of the visual environment, the operability and functionality of the equipment, and the ease of information processing. Therefore, modern biochemical rooms must have good design and high quality equipment to satisfy.
Among the modern equipment, there are central laboratory benches, side tables, medicine cabinets, vessel cabinets, and gas bottle cabinets, among which the biochemical room equipment is responsible for very important functions and is an indispensable equipment. Therefore, selection is an important issue in construction and must be given sufficient attention.
The main functions of the laboratory fume hood:
The main function is the exhaust function. In the chemical chamber, 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. Diffusion of pollutants is used near the pollution source. The number of units used in the past has been limited, and they have only been used in particularly harmful and dangerous gases and experiments that generate large amounts of heat. Only the auxiliary function of the laboratory bench.
In recent years, considering the improvement of the experimental environment, the experiments carried out on the experimental stage have gradually shifted to the inside, which requires that there are functions suitable for the use of the device. In particular, most new buildings require air conditioning, so the number of units to be used in the preliminary design phase of the building is included in the air conditioning system. Due to the fact that it occupies a very important position in the biochemical room, the number of stations used has increased dramatically from the viewpoint of improving the environment, improving labor hygiene conditions, and improving work efficiency. Followed by the ventilation ducts, piping, wiring, exhaust, etc. have become an important topic of construction.
The main purpose of use is to discharge the harmful gases generated in the experiment and protect the health of the experimenters, that is, to have a high degree of safety and superior operability, which requires the following functions:
(1) Release function: It should have a mechanism for absorbing harmful gases generated internally to absorb the outside of the cabinet, dilute it, and remove it from the outside.
(2) Do not reverse flow function: It should have the function of the airflow generated by the exhaust fan inside to prevent the harmful gas from flowing from the inside into the room. In order to ensure the realization of this function, it is a good method to connect a single fan with a single ventilator. It cannot be connected by a single pipe. It can only be concatenated in the same room of the same floor. The ventilator should be installed on the pipe as much as possible. At the end (or at the top).
(3) Isolation function: In the front, there should be a glass window that does not slide to separate the interior and exterior.
(4) Supplementary function: It should have a passage or an alternative device for inhaling air from the outside when harmful gases are discharged.
(5) Control of wind speed function: In order to prevent the escape of harmful gases inside, a certain suction speed is required. The factors that determine the intake speed of the intake air include: the amount of heat generated by the experiment content and the relationship with the number of air changes. The main thing is the nature of the experiment and the nature of the pest. It is generally stated that generally non-toxic pollutants are 0.25-0.38 m/s, toxic or dangerous pollutants are 0.4-0.5 m/s, highly toxic or slightly radioactive is 0.5-0.6 m/s, and gaseous substances are 0.5m/s, granular 1m/s.
In order to ensure such a wind speed, the exhaust fan should have the necessary static pressure, that is, the frictional resistance when the air passes through the ventilation duct. When determining the wind speed, we must also pay attention to the noise problem. When the air flows through the pipeline, it is limited to 7-10m. If the air exceeds 10m, noise will be generated. Usually, the noise limit of the indoor noise level is 70dBA. Increasing the cutting area of the pipeline will reduce the wind speed. It also reduces noise, taking into account the funding and construction issues of the pipeline, must carefully select the power of the pipeline and exhaust fan.
(6) Heat and acid and alkali corrosion resistance: There are some electric furnaces to be installed inside, and some experiments produce a lot of toxic and harmful gases such as acid and alkali, which are highly corrosive. The countertops, linings, side plates, and selected water nozzles, gas nozzles, etc. shall all have anti-corrosion function. When the use of strong acids such as sulfuric acid, nitric acid, and hydrofluoric acid in the semiconductor industry or in corrosive experiments, the entire material required for the application must be acid and alkali resistant, and must be made of stainless steel or PVC.
The categories of the fume hoods are classified according to the type of ventilation: they are classified into the upper exhaust type, the lower exhaust type, and the upper and lower simultaneous exhaust types. The wind speed in the work area is uniform. For the cold process, the lower exhaust system should be used. For the thermal process, the upper exhaust system should be used. For the process with unstable calorific value, the exhaust air outlet can be adjusted on both the upper and lower sides to adjust the heat generation in the cabinet. The ratio of the upper and lower exhaust air volume results in a uniform wind speed.
According to the way into the air classification also divided into three categories. Through the indoor air circulation in the cabinet after the discharge of outdoor air is called full exhaust type, which is a very widely used type.
When it is installed in a room with heating or temperature and humidity control requirements, in order to save energy consumption of heating and air conditioning, the method of taking outdoor air from the outside and circulating it to the outside after being circulated in the cabinet is called wind-up type.
Another is the variable air volume control type. Ordinary constant air volume system requires manual adjustment of the fixed vane damper, adjusting the amount of exhaust air, when the valve is adjusted to a certain angle to reach the desired surface wind speed. The variable air volume control is to change the air volume by adjusting the valve sensor to reach a given surface wind speed. Of course, the standard type has a low cost and the variable air volume has a high cost, which is suitable for occasions requiring high precision.
According to the classification of the use status, it can be divided into an overall lower open type, a floor type, a two-face type, a three-face glass type, a table type, a conjoined type, and a pair of radioactive experiments and synthetic experiments designed according to different experimental use needs. Special perchloric acid experiment.
Safety is the great mission pursued. The use is to ensure the safety of the user and prevent pollution to the surrounding environment.