1 Scope
This part of GB/T 25915 covers the classification of air cleanliness in cleanrooms and associated controlled environments exclusively in terms of concentration of airborne particles. Only particle populations having cumulative distributions based on threshold (lower limit) sizes ranging from 0.1~5μm are considered for classification purposes.
This part does not provide for classification of particle populations that are outside of the specified particle size range, 0.1~5μm. Concentrations of ultrafine particles (particles smaller than 0.1μm) and macroparticles (particles larger than 5μm) may be used to quantify these populations in terms of U descriptors and M descriptors, respectively.
This part cannot be used to characterize the physical, chemical, radiological, or viable nature of airborne particles.
Note: the actual distribution of particle concentrations within incremental size ranges normally is not predictable and typically is variable over time.
2 Terms and Definitions
For the purposes of this part, the following definitions apply.
2.1 General
2.1.1
cleanroom
room in which the concentration of airborne particles is controlled, and which is constructed and used in a manner to minimize the introduction, generation, and retention of particles inside the room, and in which other relevant parameters, e.g. temperature, humidity, and pressure, are controlled as necessary
2.1.2
clean zone
dedicated space in which the concentration of airborne particles is controlled, and which is constructed and used in a manner to minimize the introduction, generation, and retention of particles inside the zone, and in which other relevant parameters, e.g. temperature, humidity, and pressure, are controlled as necessary
Note: this zone may be open or enclosed and may or may not be located within a cleanroom.
2.1.3
installation
cleanroom or one or more clean zones, together with all associated structures, air-treatment systems, services, and utilities
2.1.4
classification
level (or the process of specifying or determining the level) of airborne particulate cleanliness applicable to a cleanroom or clean zone, expressed in terms of an ISO Class N, which represents maximum allowable concentrations (in particles per cubic meter of air) for considered sizes of particles
Notes:
1 The concentrations are determined by using Equation (1) in 3.2.
2 Classification in accordance with this part is limited to the range extending from ISO Class 1 through ISO Class 9.
Foreword i
Introduction ii
1 Scope
2 Terms and Definitions
3 Classification
4 Demonstration of Compliance
Annex A (Informative) Graphical Illustration of the Classes of Table
Annex B (Normative) Determination of Particulate Cleanliness Classification Using a Discrete-particle-counting, Light-scattering Instrument
Annex C (Normative) Statistical Treatment of Particle Concentration Data
Annex D (Informative) Worked Examples of Classification Calculations
Annex E (Informative) Considerations for the Counting and Sizing of Particles outside the Size Range Applicable for Classification
Annex F (Informative) Sequential Sampling Procedure
Bibliography
