ASTM F312-08(2016)

Standard Test Methods for Microscopical Sizing and Counting Particles from Aerospace Fluids on Membrane Filters

SIGNIFICANCE AND USE
5.1 Reported particle size measurement is a function of both the actual particle dimension and shape factor, as well as the particular physical or chemical properties of the particle being measured. Caution is required when comparing data from instruments operating on different physical or chemical parameters or with different particle size measurement ranges. Sample acquisition, handling, and preparation can also affect the reported particle size results.
SCOPE
1.1 These test methods cover the determination of the size distribution and quantity of particulate matter contamination from aerospace fluids isolated on a membrane filter. The microscopical techniques described may also be applied to other properly prepared samples of small particles. Two test methods are described for sizing particles as follows:  
1.1.1 Test Method A—Particle sizes are measured as the diameter of a circle whose area is equal to the projected area of the particle.  
1.1.2 Test Method B—Particle sizes are measured by their longest dimension.  
1.2 The test methods are intended for application to particle contamination determination of aerospace fluids, gases, surfaces, and environments.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 These test methods do not provide for sizing particles smaller than 5 μm.  
Note 1: Results of these methods are subject to variables inherent in any statistical method. The use of these methods as a standard for initially establishing limits should be avoided unless ample tolerances are permissible.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Sep-2016
• ICS: 49.080 - Aerospace fluid systems and components
• Technical Committee: E21 - Space Simulation and Applications of Space Technology
• Drafting Committee: E21.05 - Contamination

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F312 − 08 (Reapproved 2016)
Standard Test Methods for
Microscopical Sizing and Counting Particles from
Aerospace Fluids on Membrane Filters
This standard is issued under the fixed designation F312; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope F302 Practice for Field Sampling of Aerospace Fluids in
Containers
1.1 These test methods cover the determination of the size
F303 Practices for Sampling for Particles in Aerospace
distribution and quantity of particulate matter contamination
Fluids and Components
from aerospace fluids isolated on a membrane filter. The
F311 Practice for Processing Aerospace Liquid Samples for
microscopical techniques described may also be applied to
Particulate Contamination Analysis Using Membrane Fil-
other properly prepared samples of small particles. Two test
ters
methods are described for sizing particles as follows:
F314 Methods of Test for Identification of Metallic and
1.1.1 Test Method A—Particle sizes are measured as the
Fibrous Contaminants in Aerospace Fluids (Withdrawn
diameter of a circle whose area is equal to the projected area of
1990)
the particle.
F318 Practice for Sampling Airborne Particulate Contami-
1.1.2 Test Method B—Particle sizes are measured by their
nation in Cleanrooms for Handling Aerospace Fluids
longest dimension.
(Withdrawn 2013)
1.2 The test methods are intended for application to particle
contamination determination of aerospace fluids, gases,
3. Terminology
surfaces, and environments.
3.1 Definitions:
1.3 The values stated in SI units are to be regarded as
3.1.1 unit area—the area selected for counting particles.
standard. No other units of measurement are included in this
This may be the area of a reticle grid or some subdivision
standard.
thereof, the area of one imprinted membrane grid, or any other
accurately calibrated area.
1.4 These test methods do not provide for sizing particles
smaller than 5 µm.
3.1.2 effective filter area—the area of the membrane which
entraps the particles to be counted.
NOTE 1—Results of these methods are subject to variables inherent in
any statistical method. The use of these methods as a standard for initially
3.1.3 particle size—the size of a particle as defined by area
establishing limits should be avoided unless ample tolerances are permis-
comparison or by its longest dimension.
sible.
1.5 This standard does not purport to address all of the
4. Summary of Test Methods
safety concerns, if any, associated with its use. It is the
4.1 The membrane is examined through a microscope and
responsibility of the user of this standard to establish appro-
the particles counted according to size or size categories using
priate safety and health practices and determine the applica-
a calibrated reticle. The total number of particles present is
bility of regulatory limitations prior to use.
estimated by statistical methods from the actual number of
particles counted. Either sizing Test Method A or B may be
2. Referenced Documents
selected according to the preference and results expected.
2.1 ASTM Standards:
5. Significance and Use
These test methods are under the jurisdiction of ASTM Committee E21 on
5.1 Reported particle size measurement is a function of both
Space Simulation and Applications of Space Technology and are the direct
the actual particle dimension and shape factor, as well as the
responsibility of Subcommittee E21.05 on Contamination.
Current edition approved Oct. 1, 2016. Published October 2016. Originally particular physical or chemical properties of the particle being
approved in 1969. Last previous edition approved in 2008 as F312 – 08. DOI:
measured. Caution is required when comparing data from
10.1520/F0312-08R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F312 − 08 (2016)
instruments operating on different physical or chemical param- 8. Calibration
eters or with different particle size measurement ranges.
8.1 The sizing reticle shall be calibrated at each magnifica-
Sample acquisition, handling, and preparation can also affect
tion by comparing the reference divisions noted in 6.3 with the
the reported particle size results.
rulings on the stage micrometer. Detailed calibration proce-
dures and a discussion of errors are given in Appendix X1.
6. Apparatus
8.2 The area extrapolation factor used for statistical count-
6.1 Microscope, capable of resolving the smallest particles
ing is determined by the ratio of the area counted to the total
to be counted and producing a flat field of view.
effective area of the membrane filter.
6.1.1 The following optic combinations are recommended:
8.2.1 Unit Area—Measure the size of the appropriate unit
Minimum
area with the stage micrometer or previously calibrated reticle
Magnification Ocular Objective Numerical
and calculate its area.
Aperture
50× 10× 5× 0.15
8.2.2 Effective Filter Area (Note 3)—Measure the diameter
100× 10× 10× 0.25
of the effective filter area with a scale, caliper, or calibrated
200× 10× 20× 0.50
mechanical stage and calculate the total area. Area = π r ,
Similar ocular-objective combinations resulting in magnifi-
where r is the radius of the effective circle.
cations of 50 6 10×, 100 6 10×, and 200 6 20× may be used.
NOTE 3—Where accurate effective filtering area measurements are
The optimum equipment is a compound binocular microscope.
required, a colored pigment solution should be filtered through the
Conventional stereo microscopes will not meet these require-
filtration apparatus as described in Practice F311.
ments.
8.2.3 Area Extrapolation Factor—The total particle count
6.2 Mechanical Stage, capable of traversing the entire
for a given size range is determined as follows:
effective filter area.
C 5 C 3A / A 3N (1)
~ ! ~ !
t e u
6.3 Stage Micrometer, with 0.1 and 0.01-mm subdivisions.
where:
6.4 Provisions for variable high-intensity external oblique
C = total extrapolated count,
t
incident illumination and for a focusing condenser. A flexible
C = actual particle count,
or jointed arm is desirable.
A = effective filter area,
e
A = unit area, and
u
6.5 Reticles, inscribed with reference markings that can be
N = number of unit areas counted.
calibrated to represent the following dimensions:
Magnification Size, µm Tolerance, µm
9. Procedure
200 ± 20× 5 ±0.8
15 ±1.2
9.1 While exact details of the counting procedure depend
100 ± 10× 15 ±1.5
25 ±2.0
partly on the specific equipment chosen, all procedures must
50 ± 10× 50 ±2.5
conform to the requirements given in 9.1.1 – 9.1.9 to achieve
50 ±2.5
reproducibility. Methods A and B differ only in the sizing of
100 ±5.0
particles, and the detailed procedure given shall be used for
6.5.1 The reticles shall be as follows:
either Reticle A or B.
6.5.1.1 Reticle A, Globe and Circle Pattern, provides a
9.1.1 Blank analysis counts, which are part of the normal
means for correlation of the microscopic method with auto-
processing procedure, must be used to determine the adequacy
matic counter methods. Reticle A uses the diameter of a circle
of environmental control.
for its comparison of a particle, and automatic counter methods
9.1.2 Size and count the particles in the following order:
use either a particle volume, projected area, or particle area
particles greater than 100 µm (including fibers), 50 to 100 µm,
measurements which are all directly related to the diameter.
25 to 50 µm, 15 to 25 µm, and 5 to 15 µm. Particles smaller
6.5.1.2 Reticle B, Linear Scale, provides for measurement
than 5 µm shall not be counted by this method. Fibers (particles
of the longest linear
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F312 − 08 F312 − 08 (Reapproved 2016)
Standard Test Methods for
Microscopical Sizing and Counting Particles from
Aerospace Fluids on Membrane Filters
This standard is issued under the fixed designation F312; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 These test methods cover the determination of the size distribution and quantity of particulate matter contamination from
aerospace fluids isolated on a membrane filter. The microscopical techniques described may also be applied to other properly
prepared samples of small particles. Two test methods are described for sizing particles as follows:
1.1.1 Test Method A—Particle sizes are measured as the diameter of a circle whose area is equal to the projected area of the
particle.
1.1.2 Test Method B—Particle sizes are measured by their longest dimension.
1.2 The test methods are intended for application to particle contamination determination of aerospace fluids, gases, surfaces,
and environments.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 These test methods do not provide for sizing particles smaller than 5 μm.
NOTE 1—Results of these methods are subject to variables inherent in any statistical method. The use of these methods as a standard for initially
establishing limits should be avoided unless ample tolerances are permissible.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
F302 Practice for Field Sampling of Aerospace Fluids in Containers
F303 Practices for Sampling for Particles in Aerospace Fluids and Components
F311 Practice for Processing Aerospace Liquid Samples for Particulate Contamination Analysis Using Membrane Filters
F314 Methods of Test for Identification of Metallic and Fibrous Contaminants in Aerospace Fluids (Withdrawn 1990)
F318 Practice for Sampling Airborne Particulate Contamination in Cleanrooms for Handling Aerospace Fluids (Withdrawn
2013)
3. Terminology
3.1 Definitions:
3.1.1 unit area—the area selected for counting particles. This may be the area of a reticle grid or some subdivision thereof, the
area of one imprinted membrane grid, or any other accurately calibrated area.
3.1.2 effective filter area—the area of the membrane which entraps the particles to be counted.
3.1.3 particle size—the size of a particle as defined by area comparison or by its longest dimension.
These test methods are under the jurisdiction of ASTM Committee E21 on Space Simulation and Applications of Space Technology and are the direct responsibility of
Subcommittee E21.05 on Contamination.
Current edition approved Nov. 1, 2008Oct. 1, 2016. Published December 2008October 2016. Originally approved in 1969. Last previous edition approved in 20032008
as F312 – 97F312 – 08.(2003). DOI: 10.1520/F0312-08.10.1520/F0312-08R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F312 − 08 (2016)
4. Summary of Test Methods
4.1 The membrane is examined through a microscope and the particles counted according to size or size categories using a
calibrated reticle. The total number of particles present is estimated by statistical methods from the actual number of particles
counted. Either sizing Test Method A or B may be selected according to the preference and results expected.
5. Significance and Use
5.1 Reported particle size measurement is a function of both the actual particle dimension and shape factor, as well as the
particular physical or chemical properties of the particle being measured. Caution is required when comparing data from
instruments operating on different physical or chemical parameters or with different particle size measurement ranges. Sample
acquisition, handling, and preparation can also affect the reported particle size results.
6. Apparatus
6.1 Microscope, capable of resolving the smallest particles to be counted and producing a flat field of view.
6.1.1 The following optic combinations are recommended:
Minimum
Magnification Ocular Objective Numerical
Aperture
50× 10× 5× 0.15
100× 10× 10× 0.25
200× 10× 20× 0.50
Similar ocular-objective combinations resulting in magnifications of 50 6 10×, 100 6 10×, and 200 6 20× may be used. The
optimum equipment is a compound binocular microscope. Conventional stereo microscopes will not meet these requirements.
6.2 Mechanical Stage, capable of traversing the entire effective filter area.
6.3 Stage Micrometer, with 0.1 and 0.01-mm subdivisions.
6.4 Provisions for variable high-intensity external oblique incident illumination and for a focusing condenser. A flexible or
jointed arm is desirable.
6.5 Reticles, inscribed with reference markings that can be calibrated to represent the following dimensions:
Magnification Size, μm Tolerance, μm
200 ± 20× 5 ±0.8
15 ±1.2
100 ± 10× 15 ±1.5
25 ±2.0
50 ± 10× 50 ±2.5
50 ±2.5
100 ±5.0
6.5.1 The reticles shall be as follows:
6.5.1.1 Reticle A, Globe and Circle Pattern, provides a means for correlation of the microscopic method with automatic counter
methods. Reticle A uses the diameter of a circle for its comparison of a particle, and automatic counter methods use either a particle
volume, projected area, or particle area measurements which are all directly related to the diameter.
6.5.1.2 Reticle B, Linear Scale, provides for measurement of the longest linear dimension technique.
NOTE 2—Some reticles combine both patterns in one reticle.
6.6 Tally Counter, hand operated, for recording particle counts.
6.7 Video imaging and software packages are allowed provided they meet the calibration requirements of 6.5.
7. Sampling
7.1 Collect and process the sample in accordance with the applicable methods of the American Society for Testing and
Materials, as follows: Practice F302, Practice F311, Practice F318, and Practices F303.
8. Calibration
8.1 The sizing reticle shall be calibrated at each magnification by comparing the reference divisions noted in 6.3 with the rulings
on the stage micrometer. Detailed calibration procedures and a discussion of errors are given in Appendix X1.
8.2 The area extrapolation factor used for statistical counting is determined by the ratio of the area counted to the total effective
area of the membrane filter.
8.2.1 Unit Area—Measure the size of the appropriate unit area with the stage micrometer or previously calibrated reticle and
calculate its area.
8.2.2 Effective Filter Area (Note 3)—Measure the diameter of the effective filter area with a scale, caliper, or calibrated
mechanical stage and calculate the total area. Area = π r , where r is the radius of the effective circle.
F312 − 08 (2016)
NOTE 3—Where accurate effective filtering area measurements are required, a colored pigment solution should be filtered through the filtration
apparatus as described in Practice F311.
8.2.3 Area Extrapolation Factor—The total particle count for a given size range is determined as follows:
C 5 C 3A / A 3N (1)
~ ! ~ !
t e u
where:
C = total extrapolated count,
t
C = actual particle count,
A = effective filter area,
e
A = unit area, and
u
N = number of unit areas counted.
9. Procedure
9.1 While exact details of the counting proc
...