Fresh air volume requirements of plant clean room:
In the clean room, if there is insufficient fresh air volume, staff will have uncomfortable symptoms such as suffocation and dizziness. In order to meet the sanitary requirements of workers and ensure work efficiency, a sufficient amount of fresh air should be supplied in the clean room. In order to compensate the process equipment exhaust air in the clean room, the clean room needs to compensate the corresponding fresh air. In order to ensure the cleanliness of the clean room from the contamination of the adjacent room or the outside world and the influence of the products in the clean room or allergenic substances in the product production process on the adjacent room, the clean room needs to maintain a certain pressure difference value, which also requires Fresh air added. Therefore, the amount of fresh air required for the clean room should meet:
① Fresh air volume required to meet the health requirements of workers
The natural metabolism of workers in clean rooms continuously exhales carbon dioxide in the air shower room and emits various odors, moisture, heat and particulates, etc. These substances may also be produced during the production of various products. Therefore, if fresh air is not replenished in a timely manner, the concentration of unhealthy substances represented by carbon dioxide in clean rooms will continue to increase, and workers will stay indoors for long periods of time, and activities will be uncomfortable such as suffocation, lethargy, and dizziness. occur. In order to ensure the health of workers, there are regulations on the amount of fresh air in relevant standards and regulations promulgated by the state, and in the "Sanitary Standards for the Design of Industrial Enterprises" (GBZ l-2002), "the volume occupied by each worker is less than 20rr13. The workshop should guarantee a fresh air volume of not less than 30m3 per person per hour. The "Design Code for Heating Ventilation and Air Conditioning" (GBJ 19) stipulates that the fresh air volume of the air conditioning system should meet the following requirements: The production plant should be compensated Exhaust air, maintain the indoor positive pressure, or ensure that the maximum amount of fresh air per person is not less than 30m3 / h. "According to the amount of fresh air required per person per hour: 30rr13 / h in the United States, 42m3 / h in the United Kingdom, Japan 35n13 / h. In the 2001 edition of the "Code for Design of Clean Plants", it is stipulated that the amount of fresh air per person per hour is not less than 40rn3.
② The amount of fresh air required to supplement the exhaust air
In the production process of various products in various clean workshops, due to the characteristics of the production technology of clean sheds, some flammable, explosive or toxic and harmful gases, substances or dust may be generated, leaked, and volatilized. In the biological clean room for product production, allergenic substances, live microorganisms, or viruses may be generated, leaked, or spread. In order to ensure the safe production of clean workshops and prevent cross-contamination in the production process, technical measures must be taken to control the above-mentioned various substances and gases in the clean room air below the allowable concentration range. Generally, two methods are used in engineering. ① Set up a local exhaust system for certain process production equipment to extract various toxic and hazardous substances; ② If the average concentration of toxic and hazardous substances in the indoor air may exceed the allowable concentration specified in relevant standards, a full-room exhaust system must be set up, Reduce the concentration of toxic and harmful substances in the indoor air below the allowable concentration, and set up corresponding processing equipment in the exhaust system according to the nature and concentration of the harmful substances contained in the exhaust. However, it is difficult, complicated and costly to process the harmful substances in the exhaust gas to meet the requirements of returning them to the clean room for recycling. Therefore, the above-mentioned exhaust gas is generally treated to a level below The allowable concentration of national emission standards is discharged into the atmosphere. In order to maintain the air balance of the purification air-conditioning system, the purification workbench should be supplemented with fresh air that is the same as or slightly more than the exhaust volume (including local exhaust and whole room exhaust). Some products in the production process or the production environment purification system air, if the treatment is still unavoidable cross-contamination, it should not be recycled, you need to use a DC system, that is, purification air-conditioning system can not return air, all use fresh air to supplement.