What Is an Air Shower?
An air shower is a box-shaped device installed at the entrance of a clean room, etc. It uses dust-free air filtered through a high purity multi-layer filter called HEPA to remove dust from people’s clothes.
Uses of Air Showers
Air showers are mainly used in semiconductor and precision equipment manufacturing facilities. In most cases, they are installed at the entrance to prevent dust from entering the clean room.
To maintain the cleanliness of the clean room, it is important to remove all the dust in the air shower. Because it can remove dust from clothes in a few tens of seconds, it is sometimes installed at the entrance of apartments for pollen allergic patients.
Principle of Air Showers
An air shower has a double door with an interlock that prevents both doors from opening at the same time. When a person enters the air shower from the outside, air is injected through the jets for a set number of seconds. The air is highly purified air that has passed through a HEPA filter.
This forces the dusty air to circulate and keeps the air shower space highly purified. Even when no one is in the room, the air is gently circulated to keep the air shower space constantly at a high level of cleanliness.
The interlocks on the double doors allow only a small amount of dust to enter when exiting, which also contributes to extending the life of the HEPA filter.
How to Choose an Air Shower
Select an air shower that meets the cleanliness requirements of the clean room, as higher dust removal performance is more expensive. Cleanliness of a clean room is classified by ISO based on the size and quantity of particles inside.
Each air shower is selected after confirming its guaranteed class. It is also possible to reduce costs by selecting a simple type of Air Shower that does not have a room. If the number of people coming in and out of the room is large or frequent, a large Air Shower that can accommodate several people at the same time may be selected.
Other Information on Air Showers
1. How to Use Air Showers
An air shower is a facility that removes dust to prevent dust from being brought into the clean room. However, if it is used improperly, it will not achieve the expected dust removal effect. First, decide on a standing position with a predetermined capacity, and mark the “stop” marker. Depending on the standing position, the air velocity hitting the body will decrease, and the dust removal effect will also be reduced.
Next, adjust the air outlet slightly downward toward the standing position. This has the effect of reducing the air blowing up and reducing re-contamination caused by the dust being blown up. During the air shower, rotate 2-3 times with your arms outstretched so that the air blows over your entire body. After rotation, the unit waits in place until the set time.
Generally, set the air shower time to about 30 seconds for one-sided blowers and about 20 seconds for two-sided blowers.
2. Effects of Air Showers
An experiment was conducted to determine the correlation between the dust removal effect of an air shower and the time setting. In the experiment, the dust removal rate for each size was measured for 10, 20, and 30 seconds for the one-sided and two-sided types of air showers.
This experiment showed that the one-sided blowout type had a low removal rate of fine dust particles and was inferior in dust removal effectiveness. With the two-sided blowout type, the removal rate of each size of dust was almost equal, and the dust removal effect was high.
These results indicate that it is appropriate to select a double-sided blowout type for clean rooms that require high cleanliness. In places where cleanliness requirements are not high, it is more economical to use a single-sided blowing type to remove large dust and debris.
As for the dust removal time, experimental data for the two-sided blowout type shows that the dust removal effect is inferior at 10 s. Since there is no noticeable difference between 20 s and 30 s, it is generally recommended that the dust removal time be set at about 20 s. Since the dust removal effect of an air shower varies, depending on how it is used, it is necessary to ensure that it is used in an effective manner.