In the last article, I introduced the selection of ventilation frequency, exhaust and air supply in the ventilation design of the laboratory decoration. For details, please click "Ventilation Design in Laboratory Decoration (1)" to view. Next, we will introduce the room pressure difference and control system in ventilation design.

I. Room pressure difference

Ventilation design in laboratory decoration, under normal circumstances, unless the laboratory requires a higher cleanliness, otherwise the room must maintain a relatively negative pressure. Of course, the room pressure difference in laboratory decoration should also be determined according to the actual situation.

If there are strict temperature and humidity requirements in the laboratory, then the room pressure difference must be positive, so that the temperature and humidity can be accurately controlled without leaving safety hazards. If there is a need to prevent toxic, corrosive, high-temperature gases or volatiles from spreading to other rooms in the laboratory, the pressure difference in the room must be negative. In addition, the laboratory office area should maintain a positive pressure relative to the operating area and corridors.

II. Control system

If you want to safely and reasonably control the pressure, pressure difference, ventilation, temperature and humidity in the laboratory, you must complete the control system in the laboratory decoration. The related requirements have also gone from the early constant air volume, bistable, and variable air volume systems to the current adaptive control system.

An adaptive control system is installed in the laboratory. This system can effectively ensure the safety of personnel, and correctly control the balance of air supply and exhaust and indoor pressure, thereby providing the laboratory with maximum stability. In addition, it can also effectively reduce the upfront costs, as well as the costs of operation, energy consumption and maintenance.

Laboratory control needs to start from two aspects, namely: adjusting the temperature and humidity control of the equipment, monitoring safety facilities to protect employees. As for the choice of control system, as long as it is suitable for the current laboratory environment. As to whether the ventilation adopts a constant air volume or a variable air volume control system, it depends on the comprehensive consideration of investment and operating costs.

The constant air volume control system is mainly used to provide the total exhaust air flow for the fume hood and the heating furnace, and the total flow is maintained unchanged. This system uses a mechanical limit stop to limit the valve opening, which can reduce the flow by up to 40%. The variable air volume control system capacity is reduced by more than 10% or 20% of the uneven design.

I believe that through the introduction of these two articles, everyone has a preliminary understanding of the ventilation design in the laboratory decoration!