Working principle of clean room

A cleanroom with a cleanliness level of 10-100: To achieve an internal purification level of 100 or above, it is necessary to create a unidirectional vertical airflow of clean air inside the room. That is to say, the airflow in the clean room maintains the same direction and velocity at any point on the same section, which can make the clean airflow move away the dust particles in the room at a fast speed like a piston. To achieve vertical flow, high-efficiency filters need to be installed all over the roof in order to achieve unidirectional vertical flow and achieve a cleanliness level of 100 or above.

1K-100K cleanroom: Its airflow organization direction is different from that of Class1-100 cleanroom. The internal airflow flows at an uneven speed in a non parallel manner, accompanied by backflow and eddies. It mainly relies on clean airflow to continuously dilute the internal air, gradually discharge internal pollution, and achieve a clean effect. To achieve different levels of cleanrooms, it mainly relies on the different air volumes supplied per unit time.
Cleanroom form: It can be divided into fully enclosed and semi enclosed types.
Fully enclosed – commonly used in high demand environments or research institutions.
Working principle of clean room airflow
Airflow → Air purification system purification treatment → Fan pressurized air supply → Fan filtration unit → Clean shed → Remove dust (bacteria). Repeat the above process to achieve the purification goal.
The airflow in the clean room flows in one direction (either vertically or horizontally) and passes through the entire space at a uniform speed of generally 0.3 to 0.5 meters per second (60 to 100 feet per minute). The airflow is supplied to the greenhouse by the fan filtration unit (with high-efficiency filter) on the ceiling of the clean room. The airflow is like an air piston, flowing downwards through the greenhouse, carrying away pollutants, and then being discharged from the ground.
Advantages of Clean Room:
The structure is simple, the system construction cost is low, and it is relatively easy to expand. In some special use areas, ultra clean workbenches can be used to improve the cleanliness level of the clean room.
The main ways to control particle pollution in clean rooms are:
1. Control pollution sources and reduce the occurrence of pollution;
2. Quickly and effectively eliminate indoor pollution that has already occurred;
3. Effectively prevent outdoor pollution from entering. (or effectively prevent indoor pollution from escaping outdoors)
The concept of fluid mechanics:
1. Stable flow and unstable flow; (According to the presence or absence of time factors such as flow rate and acceleration in motion elements)
2. Gradient flow (streamlines are generally equidistant and close to straight lines) and abrupt flow; (According to the streamline shape)
Gradient flow includes both uniform flow (the extreme case of gradient flow) and non-uniform flow;
3. Laminar and turbulent flow (based on the presence or absence of particle exchange).
1、 Principle of Non Unidirectional Flow Cleanroom
Main feature: The flow cross-section of the airflow between the inflow and outflow is variable. Also known as turbulence. Fluid state essence: rapid flow, turbulent flow, stable flow.
Principle of Clean Room

(1) There are two types of orifice plate top delivery: full orifice plate top delivery and partial orifice plate top delivery. The top air velocity of the full orifice plate is low, the airflow distribution is uniform, and it can achieve a cleanliness level of 1000. Compared to full orifice plate top feeding, local orifice plate top feeding has a higher wind speed, resulting in vortices on the wall side and some rolling up along the measuring wall. After passing through the ceiling to the middle, it flows downstream with the clean air flow, mixing and contaminating the clean air flow. Its cleanliness can reach level 10000.
(2) The streamlined diffuser top delivery method is suitable for tall factories over 4 meters in terms of airflow organization.
(3) The high-efficiency filter is arranged at the air supply outlet, usually with a diffuser plate, and can achieve a cleanliness level of 1000 to 100000. It is a commonly used form of airflow organization.
(4) Side delivery is generally used, with the same side returning. This form is suitable for low rise factories and is often used for the renovation of old factories. There are many eddy currents in the side delivery room, and the cleanliness can only reach level 10000, but the engineering cost is low.
The working principle of a non unidirectional flow clean room is that when a clean airflow is sent into the room from the air supply outlet, it quickly spreads and mixes in all directions. At the same time, approximately the same amount of airflow is discharged from the return air outlet. This clean airflow dilutes the indoor polluted air, diluting the indoor air with high dust concentration until equilibrium is reached. So the faster and more uniform the airflow spreads, the better the dilution effect will naturally be.
The principle of non unidirectional flow clean room is dilution effect.
According to the working principle of non unidirectional flow cleanrooms, the cleanliness they can achieve is generally between 1000 and 10000 (6-7) levels. If designed properly, in some cases, it can reach up to 100 (5) levels. The higher the indoor air exchange rate, generally speaking, the higher the cleanliness obtained.