ASTM D6058-96(2001)

Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment

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.

General Information

• Status: Historical
• Publication Date: 09-Dec-1996
• ICS: 13.040.30 - Workplace atmospheres
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.04 - Workplace Air Quality

Relations

• Replaces: ASTM D6058-96 - Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment
• Effective Date: 10-Dec-1996
• Replaced By: ASTM D6058-96(2006) - Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment
• Effective Date: 01-Oct-2006

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D6058–96 (Reapproved 2001)
Standard Practice for
Determining Concentration of Airborne Single-Crystal
Ceramic Whiskers in the Workplace Environment
This standard is issued under the fixed designation D 6058; 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 D 6056 Test Method for Determining Concentration of
Airborne Single-Crystal Ceramic Whiskers in the Work-
1.1 This practice is intended to assist individuals in the
place Environment by Transmission Electron Microscopy
sampling and analysis of single-crystal ceramic whiskers
D 6057 Test Method for Determining Concentration of
(SCCW), such as silicon carbide and silicon nitride, in the
Airborne Single-Crystal Ceramic Whiskers in the Work-
workplace environment. It describes sampling and analytical
place Environment by Phase Contrast Microscopy
techniques used to assess the airborne concentration and size
D 6059 Test Method for Determining Concentration of
distribution of SCCW, which may occur in and around the
Airborne Single-Crystal Ceramic Whiskers in the Work-
workplace where these materials are manufactured, processed,
place Environment by Scanning Electron Microscopy
transported, or used.
1.2 The protocols currently in use for asbestos and other
3. Terminology
fibrous materials have been used as a guide in developing
3.1 For definitions of terms used in this practice, refer to
sampling and analytical procedures for characterizing fibers
Terminology D 1356.
produced from the manufacture and use of SCCW. The
3.2 Definitions:
sampling and analysis protocols described here have been
3.2.1 man-made mineral fiber, n—any inorganic fibrous
written specifically for SCCW, however, they may be appro-
material produced by chemical or physical processes.
priate for other man-made mineral fibers (MMMF).
3.2.2 single-crystal ceramic whisker, n—a man-made min-
1.3 The values stated in SI units are to be regarded as the
eral fiber that has a single-crystal structure.
standard. The values given in parentheses are for information
3.2.2.1 Discussion—Although the terms fiber and whisker
only.
are, for convenience, used interchangeably in this practice,
1.4 This standard does not purport to address all of the
whisker is correctly applied only to single-crystal fibers
safety concerns, if any, associated with its use. It is the
whereas a fiber may be single- or poly-crystalline or may be
responsibility of the user of this standard to establish appro-
noncrystalline.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Summary of Practice
2. Referenced Documents 4.1 This practice is based on a three-tier approach to the
2 quantitative assessment of airborne SCCW levels. It includes
2.1 ASTM Standards:
detailed procedures to analyze standard air sampling cassettes
D 1356 Terminology Relating to Sampling and Analysis of
by phase contrast microscopy (PCM), scanning electron mi-
Atmospheres
croscopy (SEM), and transmission electron microscopy
(TEM).
4.2 The choice of a particular analytical method shall be
This practice is under the jurisdiction of ASTM Committee D22 on Sampling
based on the visibility limitation of each instrument and an
and Analysis of Atmospheres and is the direct responsibility of Subcommittee
understanding of the actual size distribution of the fibers being
D22.04 on Workplace Atmospheres.
Current edition approved December 10, 1996. Published February 1997.
analyzed.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.3 In general, PCM is suitable for the analysis of fibers that
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
aregreaterthanapproximately0.25µmindiameter.Depending
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. on the instrument and the sample preparation method used, the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6058–96 (2001)
SEM may be capable of examining fibers as small as 0.10 µm the NIOSH 7400 A Counting Rules, fibers with aspect ratios
in diameter. TEM has been shown to be suitable for the study $3:1 are counted. The B Rules count fibers with aspect ratios
of even finer fibers. The high resolution of this instrument $5:1. The B Rules further place an upper limit on fiber
makes it well suited for the determination of the fraction of a diameterof3µm.TheBRuleswereselectedtomonitorSCCW
fiber population with diameters#0.10 to 0.25 µm. based on the nature of SCCWs which are not likely to split
4.4 In addition to an enhanced image resolution, SEM and longitudinally as are asbestos fibers. While asbestos fibers of
TEM have the further advantage of providing elemental low aspect ratio, are, in reality, bundles of finer fibrils which
composition information on a single fiber. Furthermore, TEM may split longitudinally into high aspect ratio fibrils, the
may also be used to ascertain crystallographic data on the fiber. SCCW do not have this structure and thus would not be
Thisadditionalinformationisfrequentlyhelpfulintheanalysis expected to split into higher aspect ratio fibers.
of samples which contain numerous unknown fibers and, thus,
6.1.1.2 In practice, a portion of the membrane filter contain-
SEM or TEM, or both, are preferred in such instances.
ingtheairborneparticlesisplacedonaglassslideandrendered
transparent by exposure to acetone vapor. The slide is trans-
5. Significance and Use
ferred to a phase contrast microscope and examined at a
5.1 TheSCCWmaybepresentintheworkplaceatmosphere
magnification of approximately 4003. Fibers fitting the count-
where these materials are manufactured, processed, trans-
ing rules definition are counted if they lie within a measured
ported, or used. The test methods discussed in this practice can
area. The B Rules require that fiber ends be counted and that
be used to provide guidance when monitoring airborne con-
this number then be divided by two to give the fiber count.
centrations 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 AlthoughTEM is the reference technique, PCM or SEM
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 ParallelTEM measurements shall be carried out, at least
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
SCCW is the only, or the prevalent, fiber type present. The test
reproducible level may the lower resolution techniques (that is,
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. Howev
...