What is the working principle of the air shower transfer window?

The working principle of the air shower transfer window is to combine air purification technology with air flow control. During the process of transferring items from the non-clean area to the clean area, it removes the dust particles and microorganisms adhering to their surfaces. At the same time, it prevents direct air circulation between the clean area and the non-clean area through the interlocking of the door body, thereby avoiding cross-contamination. Its core mechanism can be broken down into the following three key links:
1. Door interlocking: Blocking direct air circulation
The doors on both sides of the air shower transfer window (usually designed as double doors) are strictly interlocked through electronic interlocking devices (such as electromagnetic locks, mechanical interlocking mechanisms)
When one side door is opened, the control system will immediately lock the other side door, preventing it from being opened.
Only when the open door is completely closed and sealed will the locked state of the other side door be released and allowed to be opened.
This design physically blocks the direct convection of air between the clean area and the non-clean area, preventing the dust-laden air from the non-clean area from entering the clean area without treatment. It serves as the first line of defense against pollution.
2. High-speed clean air flow purging: Remove contaminants from the surface of items
When the items are placed in the transfer window and the doors on both sides are closed, the air shower system starts automatically and purifies the items through the following process:
Air intake and primary filtration
The fan sucks in air from inside the transfer window or from the clean area (some models draw in air from the non-clean area, but it needs to undergo more rigorous filtration). First, it passes through the primary filter (such as G4 grade) to filter out large particles of dust (diameter ≥5μm) in the air, protecting the subsequent high-efficiency filter.
High-efficiency filtration: Generate clean air
The air that has undergone initial filtration enters a high-efficiency filter (HEPA) or an ultra-high-efficiency filter (ULPA) to further filter out tiny particles.
HEPA can filter particles of 0.3μm with a particle size of ≥99.97%.
ULPA can filter particles of 0.12μm with a particle size of ≥99.999%, making it suitable for scenarios with extremely high cleanliness requirements (such as semiconductor and biological laboratories).
High-speed airflow directional purging
The filtered clean air passes through the air outlet grilles at the top or side of the transfer window (usually designed as louvers or perforated plates), and is directed to sweep the surface of the objects at a high-speed airflow of ≥20m/s.
Top-blowing type: The airflow is vertically downward, covering the top and sides of the object.
Side-blowing type: The airflow blows horizontally against each other, focusing on removing particles adhering to both sides of the items.
Full-blown type: Simultaneous blowing on the top and both sides to achieve 360° coverage without blind spots.
The impact force generated by high-speed airflow can peel off dust, hair, fibers, and other contaminants adhering to the surface of objects, and be sucked into the return air outlet at the bottom or side of the transfer window along with the airflow, forming an internal air circulation.
Pollutants are discharged or re-filtered
Air carrying pollutants will be re-drawn into the fan and enter the next round of the filter-purging cycle. Some models will directly discharge the contaminated air to the non-clean area (which needs to be connected to the outside through pipes or the exhaust system) to prevent the accumulation of pollutants inside.
Iii. Timed Control: Ensure the purification effect meets the standards
The duration of the air shower process can be preset by the control system (usually 10 to 30 seconds) and can be adjusted according to the degree of contamination of the items) :
When the preset time ends, the air shower system automatically stops, and the interior of the transfer window returns to a stationary state.
At this point, the door on one side of the clean area is unlocked, and the operator can take out the purified items to complete the transfer process.
Some high-end models also feature sensor control (such as infrared sensors detecting whether items are placed inside) or automatic delayed start functions, further enhancing operational convenience and purification efficiency.
Iv. Additional Functions: Enhance purification requirements in special scenarios
For special fields such as medicine, biology, and chemical engineering, some air shower transfer Windows will add auxiliary purification measures to work in synergy with the air shower function:
Ultraviolet sterilization: It is equipped with an internal UV-C lamp tube. After the air shower, the ultraviolet irradiation is turned on (usually for 15-30 minutes) to kill bacteria, viruses, etc. by destroying the DNA of microorganisms. It is suitable for scenarios with high sterility requirements (such as operating rooms, vaccine workshops).
Ozone disinfection: Some models can release ozone (O₃), taking advantage of its strong oxidizing property to kill microorganisms. However, it is necessary to pay attention to the impact of ozone residue on the human body and use it in conjunction with an exhaust system.
Summary: The core logic is "physical isolation + active purification"
The working principle of the air shower transfer window is essentially as follows: First, it cuts off the direct transmission path of the pollution source through the interlocking of the door body, then actively removes the contaminants on the surface of the items through high-speed clean air flow, and ultimately achieves the safe transfer of "non-clean area items → purification treatment → clean area". It is a key device for controlling cross-contamination in clean environments.