1
INTERNATIONAL STANDARD © ISO ISO 14644-1:1999(E)
1 Scope
This part of ISO 14644 covers the classification of air cleanli-
ness 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 µm to 5 µm are
considered for classification purposes.
This part of ISO 14644 does not provide for classification of
particle populations that are outside of the specified particle
size range, 0,1 µm to 5 µm. Concentrations of ultrafine particles
(particles smaller than 0,1 µm) and macroparticles (particles
larger than 5 µm) may be used to quantify these populations in
terms of U descriptors and M descriptors, respectively.
This part of ISO 14644 cannot be used to characterize the
physical, chemical, radiological, or viable nature of airborne
particles.
NOTE The actual distribution of particle concentrations within incre-
mental size ranges normally is not predictable and typically is variable
over time.
2 Definitions
For the purposes of this part of ISO 14644, the following
definitions apply.
2.1 General
2.1.1
cleanroom
room in which the concentration of airborne particles is con-
trolled, and which is constructed and used in a manner to
minimize the introduction, generation, and retention of parti-
cles 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 parti-
cles 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 metre of air) for considered sizes of particles
NOTE 1 The concentrations are determined by using equation (1)
in 3.2.
NOTE 2 Classification in accordance with this International Stan-
dard is limited to the range extending from ISO Class 1 through ISO
Class 9.
NOTE 3 The considered particle sizes (lower threshold values)
applicable for classification in accordance with this International
Cleanrooms and associated controlled environments —
Part 1:
Classification of air cleanliness
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