improve air circulation Air entering the laboratory from non laboratory environmental areas should be directly discharged from the outside of the laboratory building

-Occupational Safety and Health Administration (OSHA)

Under any conditions, the air entering the laboratory area should come from areas such as office areas, corridors, etc

-Prudent Practices

In the process of indoor pressure control in the laboratory, maintaining a specific pressure difference between indoor and outdoor is not our ultimate goal,

What we really need to achieve is to maintain a constant flow of air at a certain speed when circulating indoors and outdoors“

-American National Standards Institute (ANSI)/American Industrial Hygiene Association (AIHA) Z9.5

Three methods of negative pressure control：

1. Pressure difference control method:

The laboratory should always maintain negative pressure

Ensure that there is always a certain pressure difference between the laboratory and the corridor

2. Residual air control method:

As shown in the example diagram, ensure that the residual air volume is 10% * total exhaust air volume

3. Compensation control method:

Residual air volume control+pressure difference control

Control through residual air flow, adjust the residual air flow value when the pressure difference deviates