Ventilation and energy-saving measures for laboratory fume hoods and laboratory workstations

A fume hood is a special form of enclosed hood, and the operation process of generating harmful substances is completely carried out inside the hood. There are usually open and closed operation holes and observation holes on the fume hood. In order to prevent harmful substances from escaping due to disturbances from mechanical equipment, chemical reactions, or heat sources inside the fume hood, it is necessary to exhaust the fume hood to create negative pressure inside the hood.

The laboratory test bench itself is also a tool for conducting experiments. It is mainly composed of reagent racks, cabinets, frames, single door cabinets, and double door cabinets. These products are combined together to form the laboratory test bench. Generally, after all product combinations, the bench can withstand a weight of about 400kg/m².

1.Exhaust air volume of fume hood and laboratory bench
The main equipment for chemical experiments and analysis are fume hoods and laboratory test benches, which produce harmful gases to the human body during the experimental process. In order to avoid the diffusion of harmful gases indoors, it is necessary to dilute the harmful gases and meet emission standards before discharging them into the outdoor atmosphere. Generally, exhaust devices should be installed on the experimental cabinets and test benches, and the minimum exhaust volume should meet the above requirements at the same time.

1.1 Exhaust air volume of fume hood

The exhaust volume of a fume hood is directly related to many factors. The area inside the fume hood and the operating port are directly related to the wind speed. During use, it is especially necessary to reduce the area of the operating port while meeting the conditions for laboratory operations. Only in this way can the exhaust volume of the fume hood be better reduced. In addition, when starting the laboratory operation, it should be kept at around 600mm, and the entire process should be completed after the operation is completed. In addition, in the specific execution process, comprehensive adjustments should be made according to the position of the fume hood, the state of the gas, the properties and diffusion speed of the gas.

If V cabinet represents the exhaust volume of the fume hood (m3/h), the wind speed at its operating port is set to m/s, and f is the area of the operating port m2. After setting these parameters, the exhaust volume of the fume hood is V cabinet=v × f × 3600.

1.2 Exhaust air volume of laboratory bench

During the experiment, the harmful gases generated on the laboratory table must also be discharged immediately. The exhaust volume on the laboratory table is always controlled at 860-1600m3/(m2 · h). In addition, the exhaust volume inside the laboratory table needs to be calculated based on its own area.
Only by comprehensively calculating the exhaust air volume of the fume hood and laboratory bench can better energy-saving measures be adopted in the future and achieve better results.

2.Energy saving measures for fume hoods and laboratory tables

2.1 Effective use of supplementary ventilation cabinets

A supply air outlet can be designed above the front of the fume hood, which can send out about 70% of the air from the inside. Once the cabinet door is opened, the airflow of the supply air will form a screen at the operating port, effectively blocking harmful gases from the outside. This way, only about 30% of the air can be replenished to the room in a timely manner. When the cabinet door is closed, 70% of the total exhaust air volume can be sent into the interior of the cabinet, so that harmful substances in the cabinet can be discharged in the first time.

This type of supplementary ventilation cabinet neither affects the indoor airflow nor is disturbed by it. However, because it does not require too much indoor air to be discharged during operation, it can best play its energy-saving role in heating and air conditioning rooms. In addition to the energy generated during the air supply process, it can also save more than half of the energy.

2.2 Effective supplementation of energy-saving fresh air

In order to reduce the heat loss of exhaust and makeup air, makeup air does not need to be heated. Outdoor air is directly sent to the vicinity of the exhaust outlet through pipes, so that the intake air can enter directly without passing through the main indoor area and can be discharged without affecting the indoor temperature and the room temperature environment of the operators. There are two ways of makeup air for the laboratory table. The intake must be along the bottom edge of the laboratory table, and from the operating port and table to the exhaust port, it must be along the bottom edge of the laboratory table, and from the operating port and table to the exhaust port. It cannot be directly discharged from the inside, otherwise it will not work.

In summary, by conducting a comprehensive analysis of the structure of the experimental fume hood and laboratory bench, and combining appropriate measures in the future to find more energy-saving measures, the overall experimental environment can be improved.