Like ISO14644, the cleanroom grade standard is based on the concentration of suspended particles to classify the cleanroom (area) and the air cleanliness in the controlled environment, and only the particle swarm with cumulative distribution in the range of 0.1um to 5.0um is considered. According to particle diameter, it can be divided into conventional particles (0.1um-5.0um), ultrafine particles (<0.1um) and macroparticles (>5.0um).
1. The following tests shall be carried out for the air cleanliness of clean rooms:
Air test: clean room has been completed, clean air conditioning system has been in normal operation, indoor test without process equipment and production personnel; static test: clean room clean air conditioning system has been in normal operation, process equipment has been installed, indoor without production personnel into the case The dynamic test clean room has been tested under normal production conditions. The detection of air volume, wind speed, positive pressure, temperature, humidity and noise in the clean room can be carried out in accordance with the relevant provisions of general use and air conditioning.
II. Vacuum and Static Testing
Before testing, the clean room and its purified air conditioning system should be thoroughly cleaned. The light scattering particle counter is used to detect the leakage of the high efficiency air filter. Firstly, the number of dust particles with diameter greater than or equal to 0.5 micron in the static pressure box (or duct) on the upper side of the high efficiency air filter should be determined to be greater than or equal to 30,000 particles/liter. If not, introduce smoke and start leak detection. The sampling port of the particle counter (or leak detection device) can move at a speed of 2-4 cm/sec from 2-3 cm of the high efficiency air filter to scan the glue of the head of the whole section and the installation frame of the high efficiency air filter. When the particle counter reads more than three particles per minute per liter (or its penetration rate is greater than 0.01) with an air outlet greater than or equal to or equal to 0.5 micron, it is considered that there is obvious leakage in this area and must be plugged.
Testing contents: total air supply, total return air, fresh air, exhaust air, etc; cleanroom pressure value; cross-section air velocity and flow direction of laminar flow cleanroom; cleanliness of clean working area; adjustment test of indoor temperature, humidity and its control ability; clean room noise.
The method of measuring air cleanliness in clean working area is suitable for counting dust particles whose particle size is greater than or equal to 0.5 micron by light scattering particle counting. For dust particles with particle size greater than or equal to 5 microns. The counting method of filter microscope can also be used.
3. Dynamic testing. The airflow direction of representative measuring points is selected at the operating position of the clean working area, and the testing method is same as that of the air state and static state.