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A Clean Room is a highly controlled environment designed for manufacturing, research, or processing products that are sensitive to air pollution, especially in industries such as microElectronics, pharmaceuticals, and food processing. The construction and operation of a modular clean room requires strict control of particle concentration to ensure product quality and safety. Particle maps are an important reference tool in the construction of clean rooms. Through particle maps, the indoor particle pollution status can be accurately described, providing a basis for the design, construction, monitoring, and maintenance of clean rooms.
Particle concentration standards and grades
The particle concentration standard of a clean room is the key basis for evaluating its cleanliness. The most widely used standard internationally is the ISO 14644-1 standard, which divides clean room grades according to the concentration of particles of different particle sizes in the air. Common particle sizes include 0.1μm, 0.3μm, 0.5μm, etc. The standard requires that the particle concentration in the air of clean rooms of different levels cannot exceed a certain value. Common clean room grades include Class 1, Class 10, Class 100, etc., indicating the number of particles per cubic meter of air.
For example, according to iso 14644-1, Class 100 cleanrooms require that the number of particles of 0.5μm and above should be less than 100/ft³ (about 3,531/m³). In the more stringent Class 1 level, the number of particles of 0.3μm and above is required to be less than 1/ft³ (about 35/m³). The detection of particle concentration requires the use of equipment such as particle counters.
ISO 14644-1 standard
Classification of cleanrooms according to the number of particles
Particle size monitoring
0.1μm, 0.3μm, 0.5μm
Class 100 Cleanroom requirements
≤100 particles/ft³ (3,531 particles/m³)
Class 1 cleanroom requirements
≤1 particle/ft³ (35 particles/m³)
Definition and application of particle maps
Particle maps are graphical representations of the
distribution of air particles in cleanrooms, usually drawn using particle
counting data. By collecting particle counting data of different particle sizes,
a two-dimensional or three-dimensional particle map is formed. The particle map
can help us clearly see the particle pollution level and particle concentration
change trend in different areas of the clean room. Its application is mainly
reflected in the following aspects:
1. Clean room design optimization
Through the particle map, the pollution sources in different areas can be analyzed, the optimization design of indoor air flow can be guided, and the air purification effect can be ensured.
2. Dynamic monitoring
Real-time monitoring of particle maps can find potential pollution sources, adjust the air purification system or exhaust system in time, and ensure a clean environment.
3. Maintenance and improvement
Regularly drawing particle maps and comparing them with historical data can help managers find system failures, filter efficiency decline and other problems.
Particle map drawing method
The drawing of particle maps usually relies on high-precision particle counter equipment. First, particle sampling is required at multiple points in the clean room to ensure coverage of each key area. During the sampling process, regular sampling should be carried out according to the particle size range specified in the ISO 14644-1 standard (such as 0.3μm, 0.5μm, 1.0μm, etc.), and the sampling location, time and number of particles should be recorded.
When calculating particle concentration, the commonly used formula is:
Where C is the particle concentration (unit: number of particles/m³), N is the measured number of particles, and V is the sampling volume (unit: m³). According to the particle concentration calculation results, it can be directly corresponded to the clean room level in the ISO standard.
Sampling points
Ensure coverage of key areas of the clean room
Particle counter
Light scattering principle or laser detection of particulate matter
Drawing method
Contour map, bar graph, thermal map
Particle concentration calculation formula
Analysis and optimization of particle map
Particle map can help us deeply analyze the pollution sources of the modular clean room. Common pollution sources include personnel activities, equipment operation, poor air flow, etc. In the particle map, the pollution source is usually manifested as a high particle concentration in a specific area. During the analysis process, the following points should be focused on:
1. Pollution hotspot
The pollution hotspot areas shown in the particle map are often places with poor air circulation or dense equipment. By analyzing the hotspot location, combined with the air flow map and filter layout map, the optimization design is carried out.
2. Air flow design
The particle map can reflect the actual effect of air flow. If the particle concentration in some areas of the map is high, it may be that the air flow has not achieved the expected effect. At this time, the air supply and return system need to be adjusted.
3. Regular monitoring and maintenance
Regularly monitor the particle map of the clean room and compare it with historical data to timely detect equipment failures or changes in pollution sources, and perform maintenance and adjustments.
The role of particle maps in clean room maintenance
The maintenance of clean rooms depends on continuous monitoring and data analysis. Particle maps are an important tool for evaluating the operating status of clean rooms, which can help managers find problems in system operation. Regularly drawing particle maps and comparing data can effectively evaluate the operating status of air purification systems, filter efficiency, temperature and humidity control systems, etc. For example, if the particle map shows that the pollution concentration in a certain area is continuously high, it may mean that the air purification device in that area needs to be cleaned or the filter replaced.
According to the ISO 14644-3 standard, the inspection cycle of a clean room should be determined according to its cleanliness level and usage nature. For Class 1 and Class 10 clean rooms, particle map drawing and analysis need to be performed more frequently to ensure that their cleanliness meets the requirements.
Regular monitoring
Regular particle image detection according to standards
System maintenance
Compare particle images to find equipment failures
ISO 14644-3 standard
Clean room detection cycle
List of relevant standards and specifications
ISO 14644-1: Air cleanliness levels for clean rooms and related controlled environments
ISO 14644-3: Test methods for clean rooms and related controlled environments
GB 50073-2013: Clean room building design specifications
GB 50333-2013: Clean room operation and maintenance specifications
The above analysis can help designers and maintenance personnel to apply particle images in a targeted manner when building clean rooms, ensuring that the clean rooms always maintain the best cleanliness.
