Differential pressure control method and control requirements for clean rooms

Introduction A clean room is a room in which the concentration of suspended particles is controlled. For cleanrooms, maintaining their cleanliness levels is essential and is a requirement for cleanroom-related production activities. In general, the design, construction and operation of the clean room should minimize the interference and influence of the surrounding environment on the clean room space, and the differential pressure control is the most important to maintain the clean room cleanliness level, reduce external pollution and prevent cross-contamination. The most effective means. The static pressure difference in the clean room has the following effects: (1) When the doors and windows of the clean room are closed, the pollution of the surrounding environment is prevented from infiltrating into the clean room by the gap between the doors and windows. (2) When the clean room doors and windows are opened, ensure sufficient airflow speed, minimize the airflow of doors and windows and personnel entering the clean room, and ensure the airflow direction to minimize the ingress pollution. When clean indoor process production or activities make indoor air contain high-risk substances, such as high-sensitivity drugs such as penicillin, highly infectious high-risk viruses, bacteria, etc., the pressure difference of the clean room should be relatively negative. Domestic and foreign standards, norms [3], [4], [5], [6], [7], [8], [9] have specified the external pressure difference of the clean room, or give the differential pressure control Requirements and guidelines. This paper will discuss the requirements of clean room differential pressure control and discuss the method of clean room differential pressure control. a) Establishment of pressure difference in clean room The test and inspection of the clean room is the design and construction drawings of the construction unit according to the design unit. After all the ventilation and air-conditioning design is installed and in place, the sub-items are tested and measured separately for some projects, mainly air volume debugging and differential pressure debugging, cleanliness Test, measure the temperature and humidity of the clean room. (1) Air volume commissioning: According to the design and construction drawing design, the sending and returning pipelines are designed; the size of the design air volume is determined, the opening state of each pipeline returning air valve is determined, and the air volume of each branch is tested. This article is not covered here. (2) Cleanliness test: It is divided into test under air condition, test under static condition, and test under dynamic condition, and the content of dust in clean room is tested separately. Test under empty conditions means that the system (clean room) is in normal operation, but the process equipment and production personnel have not been tested. Test under static conditions means that the system (clean room) is in normal operation, the ...

Division of clean room air conditioning system

(a) purification of air conditioning system division principle 1, cleanliness, temperature, humidity and its accuracy of the same or similar clean room should be divided into a purification air conditioning system.Easy to control cleanliness and temperature and humidity.2. The clean room close to each other should be classified as a system, which can reduce the length of system pipelines and the crossing of pipelines. 3. When conditions permit, the mixed flow purification air conditioning system can be composed of 4, 5 unidirectional flows and 6, 7 and 8 non-unidirectional flows. 4, clean room should not be combined with the general air conditioning room as a system. 5, use the law and use time is not the same as the clean room is not suitable for a purification air conditioning system. 6, dust production, heat, harmful substances, noise room should be designed as a separate system. 7. Rooms that are highly toxic and cause fire and explosion after mixing shall not be combined into one purification air conditioning system. 8, there are highly toxic and inflammable and explosive a, b room should be a separate system, and should not return the air dc system. 9, a purification air conditioning system is not easy to be too large.In general, the purification air delivery volume should not exceed 100,000 m; otherwise, the air treatment equipment is too large, noisy, the return air duct is large, occupies a large space and area, and the use is not flexible. 10, clean air conditioning system division should also consider the air duct, return duct, exhaust duct and water, electricity, gas and other pipelines layout, as far as possible to make a reasonable, short, easy to use management, reduce the intersection and overlap. 11. The heat, humidity and purification treatment of fresh air in the air conditioning system can be centralized or decentralized The principle of dividing the local exhaust air system of the process equipment 1. The partial exhaust air system of the process equipment should not be too large, and the exhaust air points of each exhaust air system should not be too much, so that the exhaust air management and adjustment are convenient and the exhaust air effect is good. 2. One exhaust air system should not cross two or more purification air conditioning systems. 3. The exhaust air which produces highly toxic, explosive, fire, condensation, crystallization and harmful substances after mixing shall not be combined into one exhaust air system. 4. The exhaust air of different rooms and equipment should not be combined into one exhaust air system. 5.Comparison and selection of air supply type of clean room purification air conditioning system (a) purification and air conditioning air supply combined air supply type, usually also known as the centralized type of air supply.The scheme of purifying air conditioning units (air handling units AHU) set in air conditioning room, purification of all air conditioning supply air purification were conduct...