ASTM D6058-96(2011)
(Practice)Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment
Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment
SIGNIFICANCE AND USE
The SCCW may be present in the workplace atmosphere where these materials are manufactured, processed, transported, or used. The test methods discussed in this practice can be used to provide guidance when monitoring airborne concentrations of SCCW in these environments.
Because of their visibility limitations, a significant fraction of the very small thin fibers that are present in some samples may not be detected by PCM or SEM. Therefore, TEM is considered to be the reference technique for the analysis of airborne SCCW. The TEM must be used to determine both fiber count and morphology when samples are from previously uncharacterized workplaces or materials.
Although TEM is the reference technique, PCM or SEM are considered to be the primary screening methods for the analysis of airborne SCCW.
Parallel TEM measurements shall be carried out, at least initially, to provide an index or relative measure of the fraction of total fibers that are seen by PCM or SEM. Only in instances when this percentage has been shown to be at a high and reproducible level may the lower resolution techniques (that is, PCM or SEM) be relied on exclusively.
SCOPE
1.1 This practice is intended to assist individuals in the sampling and analysis of single-crystal ceramic whiskers (SCCW), such as silicon carbide and silicon nitride, in the workplace environment. It describes sampling and analytical techniques used to assess the airborne concentration and size distribution of SCCW, which may occur in and around the workplace where these materials are manufactured, processed, transported, or used.
1.2 The protocols currently in use for asbestos and other fibrous materials have been used as a guide in developing sampling and analytical procedures for characterizing fibers produced from the manufacture and use of SCCW. The sampling and analysis protocols described here have been written specifically for SCCW, however, they may be appropriate for other man-made mineral fibers (MMMF).
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D6058 − 96(Reapproved 2011)
Standard Practice for
Determining Concentration of Airborne Single-Crystal
Ceramic Whiskers in the Workplace Environment
This standard is issued under the fixed designation D6058; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D6057Test Method for Determining Concentration of Air-
borne Single-Crystal Ceramic Whiskers in the Workplace
1.1 This practice is intended to assist individuals in the
Environment by Phase Contrast Microscopy
sampling and analysis of single-crystal ceramic whiskers
D6059Test Method for Determining Concentration of Air-
(SCCW), such as silicon carbide and silicon nitride, in the
borne Single-Crystal Ceramic Whiskers in the Workplace
workplace environment. It describes sampling and analytical
Environment by Scanning Electron Microscopy
techniques used to assess the airborne concentration and size
distribution of SCCW, which may occur in and around the
3. Terminology
workplace where these materials are manufactured, processed,
transported, or used.
3.1 For definitions of terms used in this practice, refer to
Terminology D1356.
1.2 The protocols currently in use for asbestos and other
fibrous materials have been used as a guide in developing
3.2 Definitions:
sampling and analytical procedures for characterizing fibers
3.2.1 man-made mineral fiber, n—any inorganic fibrous
produced from the manufacture and use of SCCW. The
material produced by chemical or physical processes.
sampling and analysis protocols described here have been
3.2.2 single-crystal ceramic whisker, n—a man-made min-
written specifically for SCCW, however, they may be appro-
eral fiber that has a single-crystal structure.
priate for other man-made mineral fibers (MMMF).
3.2.2.1 Discussion—Although the terms fiber and whisker
1.3 The values stated in SI units are to be regarded as the
are, for convenience, used interchangeably in this practice,
standard. The values given in parentheses are for information
whisker is correctly applied only to single-crystal fibers
only.
whereas a fiber may be single- or poly-crystalline or may be
1.4 This standard does not purport to address all of the
noncrystalline.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Practice
priate safety and health practices and determine the applica-
4.1 This practice is based on a three-tier approach to the
bility of regulatory limitations prior to use.
quantitative assessment of airborne SCCW levels. It includes
detailed procedures to analyze standard air sampling cassettes
2. Referenced Documents
by phase contrast microscopy (PCM), scanning electron mi-
2.1 ASTM Standards:
croscopy (SEM), and transmission electron microscopy
D1356Terminology Relating to Sampling and Analysis of
(TEM).
Atmospheres
4.2 The choice of a particular analytical method shall be
D6056Test Method for Determining Concentration of Air-
based on the visibility limitation of each instrument and an
borne Single-Crystal Ceramic Whiskers in the Workplace
understanding of the actual size distribution of the fibers being
Environment by Transmission Electron Microscopy
analyzed.
4.3 Ingeneral,PCMissuitablefortheanalysisoffibersthat
ThispracticeisunderthejurisdictionofASTMCommitteeD22onAirQuality
aregreaterthanapproximately0.25µmindiameter.Depending
and is the direct responsibility of Subcommittee D22.04 on WorkplaceAir Quality.
on the instrument and the sample preparation method used, the
Current edition approved Oct. 1, 2011. Published October 2011. Originally
SEM may be capable of examining fibers as small as 0.10 µm
approved in 1996. Last previous edition approved in 2006 as D6058-96 (2006).
DOI: 10.1520/D6058-96R11.
in diameter. TEM has been shown to be suitable for the study
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
of even finer fibers. The high resolution of this instrument
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
makes it well suited for the determination of the fraction of a
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. fiber population with diameters ≤0.10 to 0.25 µm.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6058 − 96 (2011)
4.4 In addition to an enhanced image resolution, SEM and based on the nature of SCCWs which are not likely to split
TEM have the further advantage of providing elemental longitudinally as are asbestos fibers. While asbestos fibers of
composition information on a single fiber. Furthermore, TEM low aspect ratio, are, in reality, bundles of finer fibrils which
mayalsobeusedtoascertaincrystallographicdataonthefiber. may split longitudinally into high aspect ratio fibrils, the
Thisadditionalinformationisfrequentlyhelpfulintheanalysis SCCW do not have this structure and thus would not be
of samples which contain numerous unknown fibers and, thus, expected to split into higher aspect ratio fibers.
SEM or TEM, or both, are preferred in such instances.
6.1.1.2 Inpractice,aportionofthemembranefiltercontain-
ingtheairborneparticlesisplacedonaglassslideandrendered
5. Significance and Use
transparent by exposure to acetone vapor. The slide is trans-
ferred to a phase contrast microscope and examined at a
5.1 TheSCCWmaybepresentintheworkplaceatmosphere
where these materials are manufactured, processed, magnification of approximately 400×. Fibers fitting the count-
ing rules definition are counted if they lie within a measured
transported,orused.Thetestmethodsdiscussedinthispractice
can be used to provide guidance when monitoring airborne area. The B Rules require that fiber ends be counted and that
this number then be divided by two to give the fiber count.
concentrations of SCCW in these environments.
From this fiber count, and knowing the volume of air sampled,
5.2 Because of their visibility limitations, a significant
it is possible to calculate the fiber concentration in the air that
fraction of the very small thin fibers that are present in some
was sampled. This number is generally expressed in terms of
samples may not be detected by PCM or SEM. Therefore,
fibers per millilitre (f/mL) of air.
TEM is considered to be the reference technique for the
6.1.1.3 The PCM method only counts fibers that fit within
analysis of airborne SCCW. The TEM must be used to
the dimensional constraints of the counting rules. Thus, the
determine both fiber count and morphology when samples are
lower limit of length to be counted will be 5 µm and the
from previously uncharacterized workplaces or materials.
maximum diameter counted will be 3 µm. The lower limit of
5.3 AlthoughTEMisthereferencetechnique,PCMorSEM
diameter is determined by the resolution and contrast (visibil-
are considered to be the primary screening methods for the
ity) of the microscope which is approximately 0.25 µm.
analysis of airborne SCCW.
6.1.1.4 ThePCMmethodisalsorestrictedtocountingfibers
5.4 ParallelTEMmeasurementsshallbecarriedout,atleast
of all types; the method does not identify or differentiate
initially, to provide an index or relative measure of the fraction
betweendifferentfibertypes.Inconsequence,thePCMmethod
of total fibers that are seen by PCM or SEM. Only in instances
is applicable to measurement of those populations in which
when this percentage has been shown to be at a high and
SCCWis the only, or the prevalent, fiber type present.The test
reproduciblelevelmaythelowerresolutiontechniques(thatis,
method is rapid, inexpensive and may be readily performed
PCM or SEM) be relied on exclusively.
on-site. It is therefore a useful screening tool for monitoring
workplace environmental levels of fibers or potential worker
6. Evaluating Potential Methods
exposure to fibers. However, one must bear in mind that this
6.1 The following three test methods address the determi- approach is inherently limited to the examination of fibers
greater than approximately 0.25 µm in diameter, depending on
nation of SCCW concentrations in a
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