The pressure difference of a clean room is the static pressure difference that must be maintained between the clean room and the surrounding space. It is a common situation that a clean room maintains a positive static pressure difference with the adjacent room (abbreviated as positive pressure). Industrial clean rooms and general biological clean rooms in actual projects all maintain positive pressure.

If the static pressure difference between adjacent clean rooms (areas) is too large or there are gaps due to construction reasons, air leakage will occur. In severe cases, the air flow in the clean room will be turbulent. Therefore, effective technical measures should be taken to control the static pressure difference between clean rooms (areas). The difference range should be 5~20Pa.

GB 50073-2013 "Cleanroom Design Specifications" has the following provisions for the pressure difference control of clean rooms: A certain pressure difference must be maintained between the clean room and the surrounding space, and the positive or negative pressure difference should be maintained according to the production process requirements. The pressure difference between clean rooms of different levels and between clean areas and non-clean areas should be no less than 5Pa, and the pressure difference between the clean area and the outdoors should be no less than 10Pa.

The basic principle of clean room pressure difference control is to control the supply air volume, return air volume and exhaust air volume. When the amount of air delivered to the clean room is appropriately greater than the return and exhaust air volume, a certain positive pressure value can be maintained indoors. At this time, under the effect of the static pressure difference between indoors and outdoors, the amount of air leaking out through the loose parts of the enclosure structure is equal to the difference between the amount of air entering and exiting the machine.

The difficulty of maintaining the pressure difference lies in the fact that the mechanical air supply and air output volume are dynamically changing. For clean air conditioning systems, dust accumulation in filters will increase resistance in fresh air and air supply pipes, thus affecting air volume. The occasional start and stop of exhaust equipment will also cause changes in exhaust volume. In addition, changes in heat pressure and wind pressure will affect the pressure difference in the room due to proximity to corridors and outdoors. Therefore, the positive difference of the clean room needs to be checked frequently, and the valves of the fresh, supply, return, and exhaust air passages need to be adjusted accordingly.

Can be controlled by return air vent, residual pressure valve control, adjust return air valve or exhaust valve,

The main purpose of clean room pressure differential control is to prevent the intrusion of external pollutants and the spread of internal pollutants. In practical applications, we need to formulate appropriate pressure difference control strategies according to the specific conditions of the clean room and the production process requirements, and strengthen daily maintenance and monitoring work to ensure the stability and reliability of the pressure difference control in the clean room and ensure the smooth progress of the production process.