What is the concept of differential pressure in a clean room, how is the differential pressure forme

The differential pressure is dust-free.

The pressure of the indoor and outdoor atmospheric environments is different. Depending on the purpose of the clean room, there is both positive and negative pressure. The way to do this is by adjusting the air conditioning system.

The magnitude of the medium supply air volume and the return air volume.

In general electronic workshops, in order to prevent external dust from entering the clean room when opening and closing the door, positive pressure is generally used, so that when the door is opened, the wind will blow out to avoid dust entering. And some biopharmaceuticals.

In the laboratory, in order to prevent the bacteria and microorganisms inside from floating out of the clean room, negative pressure is used to let the wind blow inside.

The dust-free environment of the clean room is mainly achieved by the air supply and return air of the air conditioning system, and in the continuous circulation process, through the primary, medium and high-efficiency filters in the air supply duct.

Filter out dust particles, and finally achieve dust-free, and through the continuous circulation of wind, the new dust brought in by people and equipment entering the clean room is filtered out at any time to ensure the cleanliness of the clean room.

The so-called dust-free does not mean that the dust is zero, but that the number of dust particles is controlled at a very low level relative to the external atmosphere, that is, there is very little dust. Depending on the use, there are many levels of clean rooms, from level 1 to class 300,000, and there are also different standards for the number of dust particles.

The clean room must maintain a certain pressure difference, mostly micro positive pressure, and some negative pressure, in order to ensure that the clean room is not polluted by other spaces. It is used between clean rooms and outdoor, different levels of clean rooms.

We know that the airflow is from high pressure to low pressure, so the dust-free workshop will generally maintain a slight positive pressure, so that the clean air flow is blown out from the top, blown to personnel and production equipment, and becomes dirty air, and then flows to the outside. Even if there is an action to open the door, the polluted air will not flow back because of the presence of micro-positive pressure.

However, it is easy to exchange airflow between two connected clean rooms (clean room), and only the airflow from the room with a high cleanliness level to the room with a low cleanliness level will not have a bad effect on the cleanliness. Therefore, the differential pressure in a room with a high cleanliness level is greater than that in a room with a low cleanliness level.

If there are multiple clean rooms (clean rooms), they should be arranged from low to high levels, and clean rooms of the same level are best together. The static pressure difference between adjacent rooms with different cleanliness levels is generally greater than 5Pa, and the static pressure difference between the clean room (dust-free workshop) and the outdoor is greater than 10Pa, and the opening of the door is towards the room with a high cleanliness level.

The atmospheric pressure in the clean room will be slightly higher than that outside, because the air conditioner blows air indoors, but after the return air volume is lowered, it will produce positive pressure in the clean room, which will produce a pressure difference with the outside. In this way, the outside wind will not enter the clean room, so that the cleanliness of the room is guaranteed. Because the air of the air conditioner is filtered layer by layer.