ASTM D6058-96
(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
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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Designation: D 6058 – 96
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 3. Terminology
1.1 This practice is intended to assist individuals in the 3.1 For definitions of terms used in this practice, refer to
sampling and analysis of single-crystal ceramic whiskers Terminology D 1356.
(SCCW), such as silicon carbide and silicon nitride, in the 3.2 Definitions:
workplace environment. It describes sampling and analytical 3.2.1 man-made mineral fiber, n—any inorganic fibrous
techniques used to assess the airborne concentration and size material produced by chemical or physical processes.
distribution of SCCW, which may occur in and around the 3.2.2 single-crystal ceramic whisker, n—a man-made min-
workplace where these materials are manufactured, processed, eral fiber that has a single-crystal structure.
transported, or used. 3.2.2.1 Discussion—Although the terms fiber and whisker
1.2 The protocols currently in use for asbestos and other are, for convenience, used interchangeably in this practice,
fibrous materials have been used as a guide in developing whisker is correctly applied only to single-crystal fibers
sampling and analytical procedures for characterizing fibers whereas a fiber may be single- or poly-crystalline or may be
produced from the manufacture and use of SCCW. The noncrystalline.
sampling and analysis protocols described here have been
4. Summary of Practice
written specifically for SCCW, however, they may be appro-
priate for other man-made mineral fibers (MMMF). 4.1 This practice is based on a three-tier approach to the
quantitative assessment of airborne SCCW levels. It includes
1.3 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information detailed procedures to analyze standard air sampling cassettes
by phase contrast microscopy (PCM), scanning electron mi-
only.
1.4 This standard does not purport to address all of the croscopy (SEM), and transmission electron microscopy
(TEM).
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.2 The choice of a particular analytical method shall be
based on the visibility limitation of each instrument and an
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. understanding of the actual size distribution of the fibers being
analyzed.
2. Referenced Documents
4.3 In general, PCM is suitable for the analysis of fibers that
2.1 ASTM Standards: are greater than approximately 0.25 μm in diameter. Depending
D 1356 Terminology Relating to Sampling and Analysis of on the instrument and the sample preparation method used, the
Atmospheres SEM may be capable of examining fibers as small as 0.10 μm
D 6056 Test Method for Determining Concentration of in diameter. TEM has been shown to be suitable for the study
Airborne Single-Crystal Ceramic Whiskers in the Work- of even finer fibers. The high resolution of this instrument
place Environment by Transmission Electron Microscopy makes it well suited for the determination of the fraction of a
D 6057 Test Method for Determining Concentration of fiber population with diameters #0.10 to 0.25 μm.
Airborne Single-Crystal Ceramic Whiskers in the Work- 4.4 In addition to an enhanced image resolution, SEM and
place Environment by Phase Contrast Microscopy TEM have the further advantage of providing elemental
D 6059 Test Method for Determining Concentration of composition information on a single fiber. Furthermore, TEM
Airborne Single-Crystal Ceramic Whiskers in the Work- may also be used to ascertain crystallographic data on the fiber.
place Environment by Scanning Electron Microscopy This additional information is frequently helpful in the analysis
of samples which contain numerous unknown fibers and, thus,
SEM or TEM, or both, are preferred in such instances.
This practice is under the jurisdiction of ASTM Committee D-22 on Sampling
and Analysis of Atmospheresand is the direct responsibility of Subcommittee
5. Significance and Use
D22.04 on Analysis of Workplace Atmospheres.
Current edition approved Dec. 10, 1996. Published February 1997.
5.1 The SCCW may be present in the workplace atmosphere
Annual Book of ASTM Standards, Vol 11.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 6058
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 Although TEM 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 The PCM method is also restricted to counting fibers
5.4 Parallel TEM 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
between different fiber types. In consequence, the PCM method
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. 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
nation of SCCW concentrations in airborne samples. Each has
greater than approximately 0.25 μm in diameter, depending on
its own particular scope of application and varies from the
the difference between the refractive index of the immersion
other in the type of information provided. Thus, all are relevant
medium and the fibers.
in different situations, and the choice of which test method is
6.1.2 Test Method D 6059:
used will depend on the primary objective of the monitoring
6.1.2.1 The SEM may be used when a more definitive
program.
estimate of airborne concentration of SCCW is required. The
6.1.1 Test Method D 6057:
technique covers the size range covered by PCM and may
6.1.1.1 Phase contrast microscopy is the analysis method
provide information on thinner fibers down to approximately
required by the Occupational Safety and Health Administr
...
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