Laboratory ventilation system planning and design considerations and composition

There may be some unpleasant, corrosive, toxic or explosive gases in the laboratory during the experiment. If these toxic and harmful gases are not excluded from the outdoors, it will cause laboratory air pollution, which will affect the health and safety of the experimental personnel. Therefore, the planning and design of the laboratory ventilation system is very important.

I. Laboratory ventilation system planning and design considerations

1, security

Safety elements ensure the safety of operators in the laboratory and the safety of the surrounding environment. Countries have more detailed standards for laboratory safety, and safety is one of the most important goals of the laboratory.

In order to ensure the safety of the operators in the laboratory, we need accurate control of the airflow of various laboratory equipment, such as the commonly used fume hood , biosafety cabinet, universal exhaust hood and animal cages in experimental animal equipment, etc. The purpose of the control is to ensure that the toxic and harmful gases generated during the inspection will not overflow and endanger the safety of personnel. The assurance of the safety of the surrounding environment of the laboratory is usually done by ensuring the negative pressure of the laboratory.

2, pressure control

The usual biochemical laboratories are required to ensure laboratory negative pressure to prevent the poisonous gases generated by the laboratory from flowing into the adjacent office area and forming interstitial contamination.

3, energy saving

Today, energy issues have become more and more confusing, and energy conservation has become a very caring content for laboratory managers. In the usual commercial buildings, in order to save energy, only 15% of the fresh air is used, and the building is operated 10 hours a day, 5 days a week. As for the laboratory, it is often 100% fresh, running 24 hours a day, 7 days a week, so the energy consumption is huge, and it is necessary to minimize energy consumption while ensuring safety.

4, warm

Ensure that the laboratory has suitable and stable temperature and humidity, stable airflow and no odor, providing a warm working environment for laboratory staff to improve work efficiency.

5, easy to maintain

Overly complex systems often require regular maintenance, complex maintenance procedures and high costs. Therefore, a good control system should be as simple and reliable as possible, simple to maintain or no regular maintenance.

6. Reconstruction or expansion after the day

The design of the control system should try to think about future modifications and expansions. It makes the equipment such as fume hoods update, shift, increase, and change the polarity of the laboratory pressure as simple as possible.

Second, laboratory ventilation

There are two types of ventilation in general laboratories: local ventilation and full room ventilation.

1, local ventilation

Local ventilation is the near discharge of harmful substances, which can remove a large amount of harmful substances with less air volume. The energy is saved and the effect is good, and the existing laboratory conditions can be improved, which is economical and feasible.

Including: fume hood ventilation, desktop fume hood ventilation, biosafety cabinet ventilation, atomic absorption hood ventilation, universal exhaust hood ventilation, stainless steel hood ventilation, ventilation reagent cabinet ventilation, exhaust medicine cabinets and other laboratory rows Wind instruments are ventilated.

2, full room ventilation

Ventilation of the entire room, using the fresh air sent into the room to dilute the concentration of harmful gases in the room to the allowable range of sanitary standards, and at the same time, the indoor polluted air is directly or purified and discharged to the outdoor atmosphere. .

Includes: natural ventilation and mechanical ventilation.

It is often used in rooms where there are no fume hoods and hazardous substances are required.

Third, the composition of the laboratory ventilation system

Laboratory ventilation systems generally consist of ventilation equipment, ventilation ducts, mufflers, fans, and control systems.

1, ventilation equipment

The common ventilation equipment in the laboratory mainly includes: detoxification cabinet, atomic absorption hood, universal exhaust hood, and desktop hood.

(1) The detoxification cabinet is a ventilating device for safely handling harmful, harmful gases or steam. Its function is to capture, seal and transfer pollutants and harmful gases, and place them in the laboratory, so as to inhale pollutants in the working area. It is the operator that minimizes the inhalation of contaminants. The airflow in the detoxification cabinet is to suck the air in the laboratory into the detoxification cabinet through the exhaust fan, dilute the polluted gas in the detoxification cabinet and discharge it to the outside through the ventilation system to achieve low concentration diffusion.

(2) Universal suction hood is the first choice for local ventilation, simple installation and flexible positioning. Good ventilation, can effectively protect the personal safety of laboratory workers, suitable for liquid chromatography, gas chromatography or experiments with small amount of exhaust gas and no high temperature.

(3) Atomic absorption hood is mainly suitable for large-scale precision instruments such as atomic absorption instruments, which require high temperature and requires local ventilation. It requires positioning and installation, and it is also one of the factors that must be considered in the overall laboratory planning.

(4) The desktop hood is mainly suitable for organic chemistry or laboratories that require long-term distillation. It is one of the essential equipments to solve the overall ventilation requirements of such laboratories.

2, ventilation duct

For ordinary buildings, if the gas discharged from the room is not corrosive, the ventilation ducts may be galvanized steel. For laboratories with corrosive gases, the ducts shall be PVC ducts or glass ducts with corrosion-resistant materials. In the general laboratory ventilation project, PVC ducts are mostly used indoors and glass ducts are used outdoors. For laboratories with insufficient indoor height or laboratories with large air ducts, rectangular ducts are generally used to match the space on the site, and the space occupied by the ducts should be minimized on the premise of meeting the requirements of the ducts. The circular ducts are connected by inserts, and the rectangular ducts are connected by flanges, and can also be connected by means of plug-ins according to actual conditions.

3, the fan

Fans mainly include axial flow fans, diagonal flow fans, and centrifugal fans. The axial flow fan and the diagonal flow fan are suitable for the ventilation system with small wind pressure and short pipeline, for example, the ventilation system directly discharged to the window or outside the wall, referred to as: straight row; the FRP centrifugal fan is suitable for the long ventilation system of the pipeline. For example, it is discharged to the roof through a duct pipe or an external wall, referred to as: roof discharge. The material of the fan: generally divided into glass steel, PP, PVC and so on. The estimated models are selected based on air volume and wind pressure.

4, ventilation control system

The ventilation control system can adopt different control methods according to different situations, such as a single ventilation unit constant air volume ventilation control system, multiple ventilation equipment frequency conversion control systems, and multiple ventilation equipment frequency conversion + variable air volume ventilation control system.

(Content source Hengtianli Instrument Network)