ASTM F312-97

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

SCOPE
1.1 These 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 methods are described for sizing particles as follows:  
1.1.1 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 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 These methods do not provide for sizing particles smaller than 5 [mu]m.
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.

General Information

• Status: Historical
• Publication Date: 31-Dec-1996
• ICS: 49.080 - Aerospace fluid systems and components
• Technical Committee: E21 - Space Simulation and Applications of Space Technology
• Drafting Committee: E21.05 - Contamination

Relations

• Replaced By: ASTM F312-97(2003) - Standard Test Methods for Microscopical Sizing and Counting Particles from Aerospace Fluids on Membrane Filters
• Effective Date: 10-Apr-1997
• Referred By: ASTM D6439-23 - Standard Guide for Cleaning, Flushing, and Purification of Steam, Gas, and Hydroelectric Turbine Lubrication Systems
• Effective Date: 01-Jan-1997
• Referred By: ASTM D4378-22 - Standard Practice for In-Service Monitoring of Mineral Turbine Oils for Steam, Gas, and Combined Cycle Turbines
• Effective Date: 01-Jan-1997
• Referred By: ASTM D4898-16 - Standard Test Method for Insoluble Contamination of Hydraulic Fluids by Gravimetric Analysis
• Effective Date: 01-Jan-1997
• Referred By: ASTM E2088-06(2021) - Standard Practice for Selecting, Preparing, Exposing, and Analyzing Witness Surfaces for Measuring Particle Deposition in Cleanrooms and Associated Controlled Environments
• Effective Date: 01-Jan-1997
• Referred By: ASTM E2090-12(2020) - Standard Test Method for Size-Differentiated Counting of Particles and Fibers Released from Cleanroom Wipers Using Optical and Scanning Electron Microscopy
• Effective Date: 01-Jan-1997
• Referred By: ASTM F331-13(2020) - Standard Test Method for Nonvolatile Residue of Solvent Extract from Aerospace Components (Using Flash Evaporator)
• Effective Date: 01-Jan-1997
• Referred By: ASTM G121-18 - Standard Practice for Preparation of Contaminated Test Coupons for the Evaluation of Cleaning Agents
• Effective Date: 01-Jan-1997
• Referred By: ASTM D6224-22 - Standard Practice for In-Service Monitoring of Lubricating Oil for Auxiliary Power Plant Equipment
• Effective Date: 01-Jan-1997
• Referred By: ASTM D4174-23 - Standard Practice for Cleaning, Flushing, and Purification of Petroleum Fluid Hydraulic Systems
• Effective Date: 01-Jan-1997
• Referred By: ASTM F311-08(2020) - Standard Practice for Processing Aerospace Liquid Samples for Particulate Contamination Analysis Using Membrane Filters
• Effective Date: 01-Jan-1997
• Referred By: ASTM G93/G93M-19 - Standard Guide for Cleanliness Levels and Cleaning Methods for Materials and Equipment Used in Oxygen-Enriched Environments
• Effective Date: 01-Jan-1997
• Referred By: ASTM F303-08(2023)e1 - Standard Practices for Sampling for Particles in Aerospace Fluids and Components
• Effective Date: 01-Jan-1997
• Referred By: ASTM D7670-10(2021) - Standard Practice for Processing In-service Fluid Samples for Particulate Contamination Analysis Using Membrane Filters
• Effective Date: 01-Jan-1997
• Referred By: ASTM E1216-21 - Standard Practice for Sampling for Particulate Contamination by Tape Lift
• Effective Date: 01-Jan-1997

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 312 – 97
Standard Test Methods for
Microscopical Sizing and Counting Particles from
Aerospace Fluids on Membrane Filters
This standard is issued under the fixed designation F 312; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope Particulate Contamination Analysis Using Membrane Fil-
ters
1.1 These test methods cover the determination of the size
F 314 Test Method for Identification of Metallic and Fi-
distribution and quantity of particulate matter contamination
brous Contaminants in Aerospace Fluids
from aerospace fluids isolated on a membrane filter. The
F 318 Practice for Sampling Airborne Particulate Contami-
microscopical techniques described may also be applied to
nation in Clean Rooms for Handling Aerospace Fluids
other properly prepared samples of small particles. Two test
methods are described for sizing particles as follows:
3. Terminology
1.1.1 Test Method A—Particle sizes are measured as the
3.1 Definitions:
diameter of a circle whose area is equal to the projected area of
3.1.1 unit area—the area selected for counting particles.
the particle.
This may be the area of a reticle grid or some subdivision
1.1.2 Test Method B—Particle sizes are measured by their
thereof, the area of one imprinted membrane grid, or any other
longest dimension.
accurately calibrated area.
1.2 The test methods are intended for application to particle
3.1.2 effective filter area—the area of the membrane which
contamination determination of aerospace fluids, gases, sur-
entraps the particles to be counted.
faces, and environments.
3.1.3 particle size—the size of a particle as defined by area
1.3 These test methods do not provide for sizing particles
comparison or by its longest dimension.
smaller than 5 μm.
4. Summary of Test Methods
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
4.1 The membrane is examined through a microscope and
establishing limits should be avoided unless ample tolerances are permis-
the particles counted according to size or size categories using
sible.
a calibrated reticle. The total number of particles present is
1.4 This standard does not purport to address all of the
estimated by statistical methods from the actual number of
safety concerns, if any, associated with its use. It is the
particles counted. Either sizing Test Method A or B may be
responsibility of the user of this standard to establish appro-
selected according to the preference and results expected.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 5. Significance and Use
5.1 Reported particle size measurement is a function of both
2. Referenced Documents
the actual particle dimension and shape factor as well as the
2.1 ASTM Standards:
particular physical or chemical properties of the particle being
F 302 Practice for Field Sampling of Aerospace Fluids in
measured. Caution is required when comparing data from
Containers
instruments operating on different physical or chemical param-
F 303 Practices for Sampling Aerospace Fluids from Com-
eters or with different particle size measurement ranges.
ponents
Sample acquisition, handling and preparation can also affect
F 311 Practice for Processing Aerospace Liquid Samples for
the reported particle size results.
6. Apparatus
These test methods are under the jurisdiction of ASTM Committee E-29 on
Particle Size Measurement are the direct responsibility of Subcommittee E29.02 on
6.1 Microscope, capable of resolving the smallest particles
Subsieve Testing.
to be counted and producing a flat field of view.
Current edition approved April 10, 1997. Published November 1997. Originally
published as F 312 – 69. Last previous edition F 312 – 96.
2 3
Annual Book of ASTM Standards, Vol 10.05. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 312
6.1.1 The following optic combinations are recommended: mechanical stage and calculate the total area. Area = pr ,
where r is the radius of the effective circle.
Minimum
Magnification Ocular Objective Numerical
NOTE 3—Where accurate effective filtering area measurements are
Aperture
503 103 53 0.15 required, a colored pigment solution should be filtered through the
1003 103 103 0.25
filtration apparatus as described in Practice F 311.
2003 103 203 0.50
8.2.3 Area Extrapolation Factor—The total particle count
Similar ocular-objective combinations resulting in magnifi-
for a given size range is determined as follows:
cations of 50 6 103, 100 6 103, and 200 6 203 may be
C 5 ~C 3 A !/~A 3 N! (1)
t e u
used. The optimum equipment is a compound binocular
microscope. Conventional stereo microscopes will not meet
where:
these requirements.
C = total extrapolated count,
t
6.2 Mechanical Stage, capable of traversing the entire
C = actual particle count,
effective filter area. A = effective filter area,
e
6.3 Stage Micrometer, with 0.1 and 0.01-mm subdivisions. A = unit area, and
u
N = number of unit areas counted.
6.4 Provisions for variable high-intensity external oblique
incident illumination and for a focusing condenser. A flexible
9. Procedure
or jointed arm is desirable.
9.1 While exact details of the counting procedure depend
6.5 Reticles, inscribed with reference markings that can be
partly on the specific equipment chosen, all procedures must
calibrated to represent the following dimensions:
conform to the requirements given in 9.1.1-9.1.9 to achieve
Magnification Size, μm Tolerance, μm
reproducibility. Methods A and B differ only in the sizing of
200 6 203 5 60.8
15 61.2
particles and the detailed procedure given shall be used for
100 6 103 15 61.5
either Reticle A or B.
25 62.0
9.1.1 Blank analysis counts, which are part of the normal
50 6 103 50 62.5
50 62.5
processing procedure, must be used to determine the adequacy
100 65.0
of environmental control.
6.5.1 The reticles shall be as follows: 9.1.2 Size and count the particles in the following order:
6.5.1.1 Reticle A, Globe and Circle Pattern, provides a particles greater than 100 μm (including fibers), 50 to 100 μm,
means for correlation of the microscopic method with auto- 25 to 50 μm, 15 to 25 μm, and 5 to 15 μm. Particles smaller
matic counter methods. Reticle A uses the diameter of a circle than 5 μm shall not be counted by this method. Fibers (particles
with length-to-width ratio exceeding 10 to 1 and over 100 μm
for its comparison of a particle, and automatic counter methods
use either a particle volume, projected area, or particle area in length) may be identified additionally if desired. Identifica-
measurements which are all directly related to the diameter. tion may be made in accordance with Test Method F 314.
6.5.1.2 Reticle B, Linear Scale, provides for measurement 9.1.3 Place the membrane filter (in a suitable holder) on the
of the longest linear dimension technique. mechanical stage; adjust the lamp and microscope to achieve
maximum particle definition.
NOTE 2—Some reticles combine both patterns in one reticle.
9.1.4 Using 503 or lower magnification, scan the mem-
6.6 Tally Counter, hand operated, for recording particle
brane surface to assure random particle distribution and to
counts.
select the proper unit area to be used.
9.1.5 Select a unit area containing less than 20 particles in
7. Sampling
the size range counted at 503. In most cases this will represent
7.1 Collect and process the sample in accordance with the
the entire effective filtration area. Record all
...