For most of the clean space, in order to prevent the invasion of external pollution, it is necessary to keep the internal pressure of the clean project higher than the external pressure. The pressure of clean engineering space is higher than that of non-clean space; the pressure of high cleanliness level space is higher than that of adjacent low cleanliness level space.
Pressure difference maintenance depends on fresh air volume, which can compensate for the air leakage from the gap under this pressure difference. Therefore, the physical meaning of pressure difference is the resistance of air leakage (or infiltration) through various cracks in the clean room.
The air speed regulation in clean engineering refers to the air speed in clean rooms. For turbulent clean rooms, the degree of indoor pollution is reduced mainly by the dilution of air. The air velocity at the outlet of the air supply outlet should not be too high. Compared with a single air-conditioned room, the speed attenuation is required to be faster and the diffusion angle is larger. The velocity of air flowing through the horizontal plane should not be too high, so as not to blow the surface particles back into the air flow and cause re-pollution, which is generally not suitable to dry 0.2m/s.