There are cheap and expensive counters in medical laboratories. Considering the economy, purchases should be made according to actual functions. Some laboratory counters are just a computer, and there is no requirement to use ceramic panels. In fact, some advanced plates are enough. In addition, the management of some advanced laboratories has changed from 5 years ago to 15 years now. I don’t know how many laboratories can stay still in 15 years, because different leaders and different PIs change, and the space requirements of the laboratory are required. They are all different. The entire experimental counter may need to be dismantled and modified. If it is a prescriptive type, once the counter is dismantled and modified, it must be rebuilt. So we feel that the use of flexible counters can help solve this problem.

　　The importance of ventilation and air conditioning systems

　　The most important thing in the entire medical laboratory is to do a good job of ventilation and air conditioning system, which is one of the most widely affected systems. Whether the entire ventilation system is perfect or not has a direct impact on the laboratory environment, the health of the experimenters, and the operation of the test equipment. The core indicators of the design and construction of the ventilation and air-conditioning system are the laboratory pressure, the number of air changes and the temperature. These aspects must be considered.

　　How to confirm the safety and reliability of the ventilation and air-conditioning system? At present, there are not many methods, only to verify its safety through continuous testing of various indicators, so it is necessary to conduct periodic testing of various indicators in the laboratory.

　　Now let’s introduce the selection of fume hood

　　The biggest purpose of using a fume hood is to discharge the harmful gases generated in the experiment and protect the health of the experimenters. That is to say, it must have a high degree of safety and superior operability. This requires the fume hood to have the following functions:

　　(1) Releasing function: It should be equipped with a mechanism to absorb harmful gas generated inside the fume hood to absorb the gas outside the cabinet, and to dilute it and remove it from the outdoors.

　　(2) Non-reverse flow function: It shall have the function of preventing harmful gas from flowing into the room from the inside of the fume hood by the airflow generated by the exhaust fan inside the fume hood. In order to ensure the realization of this function, it is the best way to connect a fume hood and a ventilator with a single pipe. It cannot be connected by a single pipe, and it is limited to the same room on the same floor. The ventilator can be connected as much as possible. Install at the end of the pipe (or at the top of the layer).

　　(3) Isolation function: In front of the fume hood, there should be a non-sliding glass window to separate the inside and outside of the fume hood.

　　(4) Supplementary function: It should have a passage or alternative device for sucking in air from outside the fume hood when discharging harmful gas.

　　(5) Wind speed control function: In order to prevent harmful gases from escaping in the fume hood, a certain suction speed is required. The factors that determine the suction speed of the air intake of the fume hood are: the heat generated by the experiment content and the relationship with the number of air changes. The main ones are the content of the experiment and the nature of the harmful substance. It is usually stipulated that the general non-toxic pollutant is 0.25-0.38m/s, the toxic or dangerous harmful substance is 0.4-0.5 m/s, the highly toxic or has a small amount of radioactivity is 0.5-0.6m/s, and the gas is 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 when the air passes through the ventilation duct. When determining the wind speed, you must also pay attention to the noise problem. When the air flows in the pipe, the limit is 7-10m. Noise will be generated if the air is more than 10m. The noise limit value of the laboratory (indoor background noise level) is usually 70dBA. Lowering the wind speed also reduces 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 electric furnaces must be installed in the fume hood, and some experiments produce a large amount of toxic and harmful gases such as acid and alkali, which are extremely corrosive. The countertops, liners, side panels, and the selected water nozzles and air nozzles of the fume hood should all have anti-corrosion function. Where strong acids such as sulfuric acid, nitric acid, and hydrofluoric acid are used in the semiconductor industry or corrosive experiments, the overall material of the fume hood must be acid-proof and must be made of stainless steel or PVC.

　　Fume hoods are classified according to the air exhaust method: they are divided into three types: the upper exhaust type, the lower exhaust type and the upper and lower simultaneous exhaust type. In order to ensure uniform wind speed in the work area, the lower exhaust type should be adopted for the fume hood in the cold process, and the upper exhaust type should be adopted for the fume hood in the hot process. For the process of unstable heat generation, exhaust outlets can be set up and down along with the cabinet. The change of internal heat generation adjusts the ratio of the upper and lower exhaust air volume, so as to obtain a uniform wind speed.

　　Fume hoods are classified into three categories according to the way of air intake. It is called the full exhaust type, which is a type with very wide application, after the indoor air is circulated in the cabinet and discharged to the outside.

                                                                                                                                                                                 All steel fume hood

　　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 the supply air from the outside and circulating it out of the cabinet is called the supplementary air fume hood.

　　 Another type is a fume hood with variable air volume control. Ordinary constant air volume systems need to manually adjust the fixed blade air valve, adjust the exhaust air volume of the fume hood, and reach 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 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, which is suitable for occasions that require high precision.

　　According to the classification of the use status, the fume hood can be divided into an integrated lower part open type, a floor type, a two-sided type, a three-sided glass type, a table type, a conjoined type, and a radioactive experiment and a synthetic experiment designed according to the needs of different experiments. , Special fume hood for perchloric acid experiment.