The cleanliness requirement of the 100-level clean room is to take the dust and bacterial pollutants emitted from the pollution source as the premise of indoor diffusion, and dilute the pollutants with the clean air treated by the high-efficiency filter, so as to maintain the required indoor air cleanliness level.
Grade 100 clean room cleanliness requirements refer to the degree of dust contained in the air environment. When the cleanliness of a 100-grade clean room is generally required, it refers to the number of particles containing more than or equal to a certain particle size in the air per unit volume. The cleanliness of the clean room is low when the dust content is high, and the cleanliness is high when the dust content is low.
Class 100 cleanroom cleanliness grades are named by the concentration of particles ≥0.5μm. For example, a clean room with an allowable concentration of 100 PC /ft3 (about 3520pc/m3) of particles ≥0.5μm is called class 100. Our 1984 "clean workshop design standard" also used the English system grade name -- 100 level, 1000 level, ten thousand level, one hundred thousand level, the engineering is still being used in this kind of name. The four levels mentioned above are close to levels 5, 6, 7 and 8 in GB50072-2001 specification. The lower the cleanliness grade value of the cleanroom, the higher the grade. For the same grade clean room, the concentration of 1~2 particle sizes can be controlled according to the process requirements. For example, a level 6 cleanroom may require a particle concentration of ≥0.5μm not greater than 35200pc/m3 and a particle concentration of ≥5μm not greater than 293PC /m3.
Cleanliness monitoring and management system of 100-grade clean room:
Use of clean area:
(1) Personnel entering the clean area should be regularly trained in basic knowledge of microbiology, hygiene knowledge and clean operation;
(2) Personnel entering and exiting the clean area must enter the clean area according to the standard operating procedures for entering and exiting the clean area of the corresponding level;
(3) The limit of the number of people entering the clean area should be clear and strictly implemented in the standard operating procedures for personnel entering and exiting the clean area of each workshop;
(4) All materials and appliances used in the clean area must be cleaned according to the prescribed procedures. Items entering the clean area should be cleaned and treated outside the area and enter the area through the transfer window.
(5) The air conditioning in the clean area should be carried out continuously. After the end of production, the air conditioning system should continue to run for 4 hours before stopping. The system must be disinfected before it can run again.
(6) Waste should be stored in special containers, cleaned up in time every day, and sent out of the window by the transfer window.
Monitoring of clean area of 100-grade clean room:
(1) In order to ensure the purification of the environment and cleanliness of the clean area, it is necessary to regularly monitor the clean area;
(2) If the following conditions are found, the HEPA filter should be replaced;
A. Airflow velocity ≤0.25m/s, even after the replacement of primary and medium effect air filtration, airflow velocity still cannot increase;
B. The HEPA filter is leaking beyond repair.
Maintenance requirements for clean area of class 100 clean room:
(1) Safety measures such as safety doors, emergency lights and alcohol cabinets should be set up in the clean area;
(2) The management of clean areas should be recorded;
(3) In addition to the daily management of the user, the air conditioning system and the air purification equipment in the clean area should be overhauled once a year. In case of any abnormality during production, it should be overhauled in time and verified after overhaul.
Grade 100 Cleanroom cleanliness and methods
The air cleanliness of the clean room should be as follows:
Air condition: The clean room has been completed, the purification air conditioning system has been in normal operation, and the indoor process equipment and production personnel are not available.
Static: the clean room air conditioning system has been in normal operation, the process equipment has been installed, and there is no production personnel in the room.
Dynamic: The clean room has been under normal production. The detection of air volume, wind speed, positive pressure, temperature, humidity and noise in the clean room can be carried out according to the relevant provisions of general and air regulation.
For the count of dust particles with particle size greater than or equal to 0.5 micron, light scattering particle counting method should be adopted. For particle size greater than or equal to 5 microns can also be counted by filter microscope.
Clean room non-unidirectional flow pattern used to be called Turbulence type (Turbulence). Non-unidirectional flow is a kind of non-uniform Airflow distribution. Its speed and direction are different in different locations of the clean room. The following figure shows the air distribution of non-unidirectional flow.
Therefore, the number of air changes required by non-unidirectional flow clean rooms will vary greatly with the cleanliness required and the diffusion of indoor pollutants.
The air distribution form of non-unidirectional flow clean room is divided into the following categories according to the different installation ways of high-efficiency filter and return air outlet: top feed, side lower return; Side send, side back; Top feed, top back.