What Is Air Shower? - Air Shower For Cleanroom
- 13, 04, 2022
1. What is an air shower?
Air shower is a specialized chamber that works as an entryway to the cleanroom to keep the cleanroom uncontaminated. It employs high pressure and high-velocity HEPA-filtered air to dislodge and remove particles from surfaces of personnel and products before they enter cleanroom.
Air shower is installed between cleanroom and non-cleanroom. Normally, air showers are put between a gowning room and a cleanroom. After personnel wears cleanroom clothing, they enter the air shower so that the air dislodges any residual from clothing.
Some air showers are placed between cleanrooms of different cleanliness classes.
2. The history of cleanroom air shower
The first air shower was launched in 1892. At that time, the US Department of Defense tried and failed many times in the development of high-precision equipment. It was detected that the production environment contained particulate matter, resulting in inaccuracy. Finally, the first cleanroom and the first air shower were designed by several relevant departments to overcome particle contamination.
Since the invention of the cleanroom and air shower, all walks of life have continuously made new breakthroughs in a cleanroom in order to improve their competitiveness.
For more than 200 years, air shower has been widely used. It is used in cleanrooms with high/medium/low requirements. The air shower has also been included in the required equipment by international multi-industry standards (QS, GMP, ISO, etc.).
In recent years, the air shower has become more and more developed. In particular, the voice prompts of the intelligent voice air shower can let people complete the blowing and dust removal process in an orderly manner.
The purification effect is upgraded, especially the clean fluid filtered by the filter can be sprayed from all directions by rotating the nozzle. The particles are filtered through the high-efficiency filter and then circulated to the air shower.
3. Why do we need a cleanroom air shower?
Cleanroom is an environment where parameters such as cleanliness, pressure, humidity, etc are strictly controlled.
Even a small number of particles can lead to poor working performance inside cleanroom. For example, pharmaceuticals produced in cleanrooms can be damaged if the cleanroom is contaminated by too much particulate.
That’s why we need a cleanroom air shower. Air shower helps workers get rid of harmful contaminants on their clothing before entering the cleanroom.
4. Air shower application
Air shower is used in various cleanrooms and non-clean workshops such as microelectronics, optoelectronics, semiconductors, pharmaceuticals, food, chemicals, aviation, automobiles, printing, laboratories, etc.
It is used to remove particles larger than 0.3 microns from personnel during the process of entering a high-class cleanroom from a low-class clean room, so as to prevent people from bringing contamination after entering the cleanroom.
The air shower also plays the role of airflow buffer room. When opening the door, there is airflow. The air shower with a positive pressure design can stop the air from low-class cleanroom or non-cleanroom flow inside the air shower, which can avoid air contamination.
5. Air shower working principle
A cleanroom air shower is an isolated chamber with a self-contained blower and motor. When a worker enters the chamber, the blower turns on. With dual interlocked doors, the room is like an airlock.
And how does an air shower work?
The worker enters an air shower from the gowning room or non-cleanroom. The door is automatically locked. Then, the air shower starts blowing air with high velocity. The air streams scrub off the particles. After a total of about 10-20 seconds of this process, the second door unlocks, and the worker steps outside to the cleanroom.
Watch our cleanroom air shower working process video:
“Are air showers effective?”
The effectiveness of an air shower relates directly to its proper design and use. Many recent tests conducted show that air shower is 35 to 90 percent effective in contamination removal.
The reason why the air shower can remove the dust from all parts of the worker has a strong connection with the two-stage filter system inside the air shower. After filtering, the air is blown out through the air shower nozzle. After being compressed by the air shower nozzle, the blown air velocity reaches 25 m/s.
According to many tests of the League of Nations, particles larger than 0.3 microns can be taken away by 99.999% at this velocity, so the air velocity should not be lower than 25 m/s in the international standard.
In addition, GMP cleanrooms need to be equipped with a sterilization system. With the improvement of technology and product requirements, the air showers used in cleanrooms in many industries need to be equipped with germicidal lamps to remove the bacteria hidden in the air shower system, thereby avoiding cleanroom contamination.
6. Air shower structure
An air shower is composed of main parts, including body, controller, centrifugal blower, filter system (HEPA filter), air nozzles, and interlocked doors.
Body: The casing is made of powder-coated cold-rolled steel or stainless steel. The chamber is usually made of stainless steel SUS304. The thickness is 1.0mm
Filter system: High-efficiency filter HEPA H13 or H14 with efficiency of 99.99% at 0.3 microns. Pre-filter (G4) is optional
Door: Doors are equipped with an interlock system and a high-quality door closer
Controller: Advanced high-tech integrated circuit board, LCD display blowing time. The air showering time is adjustable from 0 to 99 seconds.
Blower: 2 blowers for large air volume air shower on both sides, equipped with 18 stainless steel nozzles, power: 0.55KW/unit, to ensure the shower effect. The air velocity is around ≥22-25 m/s
7. Air shower specification
|Number of passers (at a time)||1 person||2 persons|
|Casing material||Stainless steel 201/304 and powder-coated steel|
|Air shower external dimension (WxDxH)||1400x1000x2100 mm||1400x1500x2100 mm|
|Air shower internal dimension (WxDxH)||800x900x1960 mm||800x1400x1960 mm|
|Nozzle number||12 (6 pieces on each side)||24 (12 pieces on each side)|
|Air velocity||25-32 m/s|
|Air shower time||0-99s adjustable|
|Filter||600x600x120 mm||820x600x120 mm|
|Filter efficiency||99.99% at ≥0.3μm|
|Light||Built-in type LED|
|Max power (W)||1100W||2200W|
8. How to choose the right cleanroom air shower
There are the following factors you should consider when selecting an air shower:
- A modular air shower is recommended because it is easy to configure, ship, and install.
- The air shower should be made of stainless steel as it is easy to clean and chemical resistant
- The blowers should supply a high volume of air. Pre-filter and HEPA filters should be used in the filter system for excellent filtering results.
- Air nozzles should be adjustable and evenly-spaced