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Room air technology
Cleanroom air conditioning systems must deliver purified air at a specific rate to maintain a specific class of room cleanliness.
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The air is supplied to the clean rooms in such a way that there are no stagnant areas where dust particles can settle and accumulate. The air must also be conditioned in terms of temperature and humidity to meet the requirements of the room's climate parameters.
In addition, a certain amount of conditioned air is introduced into the room to create overpressure.
General facts
Ventilation systems ensure that the required volume of air is supplied in accordance with hygiene regulations and that pollutants are removed. They filter the flow at the inlet to achieve the required cleanliness class, while maintaining the specified microclimate parameters.
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The air exchange volume for each factor is evaluated in the design phase. If a higher value of this parameter is required, at the expense of cleaning, a recalculation is made to reduce it.
The following parameters must be considered:
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-Recovery time after entry of the pollutant
-Air velocity
-Temperature and humidity
-Removal of contaminations
Features of air circulation
The design of cleanroom ventilation and air conditioning systems is a process that requires special equipment.
Special attention is paid to the filter system of the supplied air. For this purpose, filters of three groups are installed:
- for coarse cleaning of mechanical impurities
- for ultra-fine cleaning
- antibacterial elements
- Ultrafine filter HEPA, ULPA
Microfilters are installed in the air distributor, just before entering the clean rooms.
A whole complex of ventilation systems for cleanrooms is involved in creating the microclimate: Fans / automatic dehumidification and humidification / heating and cooling devices / shut-off and control valves / air inlets, distributors and other mechanisms.
To ensure that the air ducts and filter chambers always remain sterile, the project specifies the frequency of their antimicrobial treatment.
In clean rooms it is common to use a supply and exhaust air system. Clean air is supplied from above under pressure. The cooled mass of a certain humidity level gradually descends from the ceiling to the floor and traps the dust in the hood. Since the speed of movement is low, the settled dust does not form vortices and is not dispersed.
Requirements
The ventilation system must meet the following requirements:
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- Reduction of the level of harmful impurities and bacteria in the air
- Ensures the required room temperature and humidity
- Maintaining a minimum air exchange rate with the appropriate standard