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Clean room air conditioning automatic control system

2024/4/8

First, the object of clean room air conditioning control

1. Temperature
The temperature control of the clean room is mainly determined by the process, and the temperature base and accuracy are improved according to the needs. In general, the temperature base is low. For example, the temperature of the clean room in the electronics factory is much lower than that of the comfort air conditioner. Therefore, the cooling load in summer is also larger. In addition, the heat of the process equipment is relatively large, that is, the temperature disturbance is very large, and the change is also very large, the use coefficient of the process equipment is changed according to the change of the yield variety, and the product is changed according to the market. To sum up, features: low temperature base, large load changes.
2. Humidity
Clean room temperature control is also based on process requirements, such as electronics factory, pharmaceutical factory relative humidity base is also low, about, but not too low, if too low, easy to produce static electricity.
3. Positive and negative pressure values
In the clean room, there will be toxic and harmful waste heat masonry in the production process, which needs to be discharged to the outside, and in order to ensure the cleanliness of the room, under normal circumstances, it is required to maintain positive pressure indoors (there are also special requirements, and maintain negative pressure), according to different cleanliness, the requirements of positive pressure value are different.
4. Cleanliness
Because the cleanliness of the production environment and the qualified rate of the product have a close relationship, therefore, the clean room requirements for comprehensive and regular testing, if found that the cleanliness does not meet the requirements of the process, should be timely alarm.
5. Concentration detection of flammable, explosive, toxic and harmful gases
When the concentration of flammable and explosive, toxic and harmful gases reaches the specified limit, the accident exhaust air should be started and the alarm should be given.

Second, the difference between clean room air conditioning control and general air conditioning control

1. General air conditioning automatic control methods can be applied in clean air conditioning automatic control projects, because the production process with cleanliness requirements for the production environment generally has higher requirements for temperature and humidity. For example: the temperature base is low and there are high precision requirements, which brings a certain difficulty to temperature and humidity control, coupled with the low base of humidity control, the requirements of higher precision will be more difficult, of course, this is a higher requirement for automatic control technology.
2. The cleanliness of the clean room is to replace the polluted air with a certain amount of clean air conditioning to meet the requirements of the production process. Therefore, the air supply volume is a constant parameter, and the automatic control method with variable air volume and fixed air dew point is not applicable. Generally, the constant air volume and dew point are used to meet the requirements of indoor temperature and humidity, which is the difference from general air conditioning control.
3. If the air conditioning form of dry coil plus FFU is used, if the indoor cooling and heat load changes, the indoor temperature is generally controlled by adjusting the cold and hot water volume of the dry coil. The indoor humidity control is generally to adjust the air supply state of the fresh air system to meet the requirements of the room.
4. By balancing the supply air volume, return air volume, exhaust air volume and fresh air volume, to meet the requirements of maintaining positive pressure value in the room. The automatic control should have the means to achieve balance when the above air volume changes, and meet the requirements of the indoor positive pressure value.