ASTM D6057-96(2011)
(Test Method)Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Phase Contrast Microscopy (Withdrawn 2020)
Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Phase Contrast Microscopy (Withdrawn 2020)
SIGNIFICANCE AND USE
The SCCW may be present in the workplace atmosphere where these materials are manufactured, processed, transported, or used. This test method can be used to monitor airborne concentrations of fibers in these environments. It may be employed as part of a personal or area monitoring strategy.
This test method is based on dimensional considerations only. As such, it does not provide a positive identification of the fibers counted. Analysis by SEM or TEM is required when additional fiber identification information is needed.
Note 1—This test method assumes that the analyst is familiar with the operation of PCM instrumentation and the interpretation of data obtained using this technique.
This test method is not appropriate for measurement of fibers with diameters less than approximately 0.25 μm due to visibility limitations associated with PCM. The SEM or TEM methods may be used to provide additional size information of SCCW if needed (refer to Practice D6058 for additional information on the use of these methods).
Results from the use of this test method shall be reported along with 95 % confidence limits for the samples being studied. Individual laboratories shall determine their intralaboratory coefficient of variation and use it for reporting 95 % confidence limits (1,3,4).
SCOPE
1.1 This test method covers the sampling methods and analysis techniques used to assess the airborne concentration of single-crystal ceramic whiskers (SCCW), such as silicon carbide and silicon nitride, which may occur in and around the workplace where these materials are manufactured, processed, transported, or used. This test method is based on the collection of fibers by filtration of a known quantity of air through a filter. The filter is subsequently evaluated with a phase contrast microscope (PCM) for the number of fibers meeting appropriately selected counting criteria. This test method cannot distinguish among different types of fibers. This test method may be appropriate for other man-made mineral fibers (MMMF).
1.2 This test method is applicable to the quantitation of fibers on a collection filter that are greater than 5 μm in length, less than 3 μm in width, and have an aspect ratio equal to or greater than 5:1. The data are directly convertible to a statement of concentration per unit volume of air sampled. This test method is limited by the diameter of the fibers visible by PCM (typically greater than 0.25 μm in width) and the amount and type of coincident interference particles.
1.3 A more definitive analysis may be necessary to confirm the identity and dimensions of the fibers located with the PCM, especially where other fiber types may be present. Such techniques may include scanning electron microscopy (SEM) or transmission electron microscopy (TEM). The use of these test methods for the identification and size determination of SCCW is described in Practice D6058 and Test Methods D6059 and D6056.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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.
WITHDRAWN RATIONALE
This test method covers the sampling methods and analysis techniques used to assess the airborne concentration of single-crystal ceramic whiskers (SCCW), such as silicon carbide and silicon nitride, which may occur in and around the workplace where these materials are manufactured, processed, transported, or used.
Formerly under the jurisdiction of Committee D22 on Air Quality, this test method was withdrawn in January 2020 in accordance with section 10.6.3 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated ...
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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: D6057 − 96 (Reapproved 2011)
Standard Test Method for
Determining Concentration of Airborne Single-Crystal
Ceramic Whiskers in the Workplace Environment by Phase
Contrast Microscopy
This standard is issued under the fixed designation D6057; 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 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the sampling methods and
responsibility of the user of this standard to establish appro-
analysistechniquesusedtoassesstheairborneconcentrationof
priate safety and health practices and determine the applica-
single-crystal ceramic whiskers (SCCW), such as silicon car-
bility of regulatory limitations prior to use.
bide and silicon nitride, which may occur in and around the
1.6 This international standard was developed in accor-
workplace where these materials are manufactured, processed,
dance with internationally recognized principles on standard-
transported,orused.Thistestmethodisbasedonthecollection
ization established in the Decision on Principles for the
offibersbyfiltrationofaknownquantityofairthroughafilter.
Development of International Standards, Guides and Recom-
The filter is subsequently evaluated with a phase contrast
mendations issued by the World Trade Organization Technical
microscope (PCM) for the number of fibers meeting appropri-
Barriers to Trade (TBT) Committee.
ately selected counting criteria. This test method cannot
distinguish among different types of fibers. This test method
2. Referenced Documents
may be appropriate for other man-made mineral fibers
2.1 ASTM Standards:
(MMMF).
D1193Specification for Reagent Water
1.2 This test method is applicable to the quantitation of
D1356Terminology Relating to Sampling and Analysis of
fibers on a collection filter that are greater than 5 µm in length,
Atmospheres
less than 3 µm in width, and have an aspect ratio equal to or
D4532Test Method for Respirable Dust in Workplace At-
greater than 5:1. The data are directly convertible to a
mospheres Using Cyclone Samplers
statementofconcentrationperunitvolumeofairsampled.This
D6056Test Method for Determining Concentration of Air-
test method is limited by the diameter of the fibers visible by
borne Single-Crystal Ceramic Whiskers in the Workplace
PCM (typically greater than 0.25 µm in width) and the amount
Environment by Transmission Electron Microscopy
and type of coincident interference particles.
D6058Practice for Determining Concentration of Airborne
1.3 Amore definitive analysis may be necessary to confirm
Single-Crystal Ceramic Whiskers in the Workplace Envi-
theidentityanddimensionsofthefiberslocatedwiththePCM,
ronment
especially where other fiber types may be present. Such
D6059Test Method for Determining Concentration of Air-
techniques may include scanning electron microscopy (SEM)
borne Single-Crystal Ceramic Whiskers in the Workplace
or transmission electron microscopy (TEM). The use of these
Environment by Scanning Electron Microscopy
test methods for the identification and size determination of
E691Practice for Conducting an Interlaboratory Study to
SCCW is described in Practice D6058 and Test Methods
Determine the Precision of a Test Method
D6059 and D6056.
3. Terminology
1.4 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information 3.1 Definitions:
only. 3.1.1 analytical sensitivity, n—airborne fiber concentration
represented by a single fiber counted in the PCM.
3.1.1.1 Discussion—Although the terms fiber and whisker
This test method is under the jurisdiction of ASTM Committee D22 on Air
Quality and is the direct responsibility of Subcommittee D22.07 on Sampling and
Analysis of Asbestos. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2011. Published October 2011. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1996. Last previous edition approved in 2006 as D6057–96 (2006). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6057-96R11. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6057 − 96 (2011)
are, for convenience, used interchangeably in this test method, ratory coefficient of variation and use it for reporting 95%
whisker is correctly applied only to single-crystal fibers confidence limits (1, 3, 4).
whereas a fiber may be single- or poly-crystalline or may be
6. Interferences
noncrystalline.
6.1 All fibers meeting the dimensional criteria in Section 3
3.1.2 aspect ratio, n—the ratio of the length of a fiber to its
are not necessarily of the same composition. Since the PCM
width.
method does not differentiate based on chemistry or
3.1.3 fiber, n—for the purpose of this test method,an
morphology, all fibers in accordance with the definitions in
elongated particle having a length greater than 5 µm, a width
Section 3 shall be counted.
less than 3 µm, and an aspect ratio equal to or greater than 5:1.
6.1.1 This test method has been designed to filter air for the
3.1.4 man-made mineral fiber, n—any inorganic fibrous
determination of fiber concentration. However, filtration of air
material produced by chemical or physical processes.
also involves collection of extraneous particles. Extraneous
3.1.5 single-crystal ceramic whisker, n— a man-made min-
particles may obscure fibers by overlay or by discoloration of
eral fiber that has a single-crystal structure.
the filter. This situation can be managed by regulating the air
volume sampled and thus the filter loading. Fibers should
3.2 For definitions of other terms used in this test method,
appear separated from other particles to ensure an adequate
see Terminology D1356.
opportunity for their recognition as separate entities in the
PCM and accurate counting. Some coincident particulate
4. Summary of Test Method
agglomeration does occur even with these guidelines.Analyze
4.1 The sample is collected on a mixed cellulose ester
an alternate filter with a reduced loading if the obscuring
(MCE) filter by drawing air, using a sampling pump, through
condition appears to exceed 15% of the filter area (5).
an open-face 25-mm electrically conductive sampling cassette
Redeposition of a portion of an overloaded filter is permitted
assembly (1, 2). Asectionoftheopaquefilterisconvertedinto
only in circumstances where an alternate filter is not available
an optically transparent homogeneous specimen using an
and cannot be obtained through resampling (see 10.1.9).
acetone vaporizer. The fibers are counted by PCM at a
magnification of approximately 400× using the criteria dis-
7. Apparatus and Reagents
cussed in Section 11. Results are expressed as a fiber concen-
7.1 Sampling Cassette—Use a 25-mm, electrically conduc-
tration per unit volume of air and a fiber loading per unit area
tive cassette assembly such as a three-piece cassette with an
of filter. The airborne concentration is expressed as fibers per
extension cowl or retainer ring, or both, containing a 0.45-µm
millilitre(f/mL)andthefiberloadingisexpressedasfibersper
2 pore size MCE filter and a support pad. Seal the cassette
square millimetre (f/mm ).
assembly with shrink tape. Reloading of used cassettes is not
permitted.
5. Significance and Use
7.2 Personal Sampling Pump—Use a portable battery-
5.1 TheSCCWmaybepresentintheworkplaceatmosphere
operated pump for personal sampling. Each pump must be
where these materials are manufactured, processed,
capable of operating within the range from 0.5 to 4 L/min and
transported, or used. This test method can be used to monitor
continuously over the chosen sampling period (1). The flow
airborne concentrations of fibers in these environments. It may
mustbefreefrompulsation.Allpumpsshallbecalibratedprior
be employed as part of a personal or area monitoring strategy.
to use (6).
5.2 Thistestmethodisbasedondimensionalconsiderations
7.3 Area Sampling Pump—Use a personal sampling pump
only.Assuch,itdoesnotprovideapositiveidentificationofthe
or a non-portable high-volume pump for area sampling. Each
fibers counted. Analysis by SEM or TEM is required when
pump shall be capable of operating within the range from 0.5
additional fiber identification information is needed.
to 16 L/min and continuously over the chosen sampling period
NOTE 1—This test method assumes that the analyst is familiar with the
(1). The flow shall be free from pulsation. All pumps shall be
operation of PCM instrumentation and the interpretation of data obtained
calibrated prior to use (6).
using this technique.
7.4 Vinyl Tubing, or equivalent.
5.3 This test method is not appropriate for measurement of
fibers with diameters less than approximately 0.25 µm due to 7.5 Microscope—Positivephasecontrastlight,withgreenor
visibility limitations associated with PCM. The SEM or TEM
blue filter, 8 to 10× eyepiece, and 40 to 45× phase objective
methods may be used to provide additional size information of
(total magnification approximately 400×); numerical aper-
SCCW if needed (refer to Practice D6058 for additional
ture=0.65 to 0.75.
information on the use of these methods).
7.6 Acetone Vaporizer—A device used to clear the MCE
5.4 Resultsfromtheuseofthistestmethodshallbereported
filter by exposure to a small amount of vaporized acetone.
along with 95% confidence limits for the samples being
7.7 Graticule, with standardized 100-µm diameter circular
studied. Individual laboratories shall determine their intralabo- −3 2
field at the specimen plane (calibrated area≈7.8×10 mm ),
with the capability to compare diameters and lengths at 3 and
5 µm, respectively, within the field of view.
The boldface numbers in parentheses refer to a list of references at the end of
this test method. NOTE 2—The graticule is custom-made for each microscope. Specify
D6057 − 96 (2011)
disk diameter needed to exactly fit the ocular of the microscope and the
0.5and4L/min (1).Typically,asamplingratebetween0.5and
diameter (millimetres) of the circular counting area (see section 12.2.1).
2.5 L/min is selected (2-5,7). Also see Test Method D4532.
TheWalton-BeckettTypeG-24graticuleorotherequivalentgraticulesare
8.5.2 Placeareasamplesonanextensionrodfacingdownat
recommended. Graticules designed for the NIOSH 7400Arules, such as
a 45° angle.Adjust the calibrated flow rate to a value between
the Walton-Beckett Type G-22, are not recommended.
0.5and16L/min (1).Typically,asamplingratebetween1and
NOTE 3—In some microscopes, adjustments of the interocular distance
will change the tube length and hence magnification of the microscope.
10 L/min is selected (8).
Each analyst shall separately measure the diameter of his or her field of
8.5.3 Set the sampling flow rate and time to produce an
view and this value shall be used in all calculations.
optimumfiberloadingbetween100and1300f/mm (1,2).The
7.8 Phase Shift Test Slide equivalent to HSE/NPL.
time of sampling can be estimated by using the following
equation:
7.9 Telescope, (ocular phase-ring centering) or Bertrand
lens.
~A !~F !
c L
t 5 (1)
Q C 10
~ !~ !
7.10 Stage Micrometer, (0.01-mm divisions).
e
7.11 Tweezers. where:
A = active filter collection area (;385 mm for 25-mm
7.12 Scalpel Blades. c
filter),
7.13 MCE Filters, 25 mm, 0.45 µm and 0.22 µm.
t = time, min,
7.14 Funnel/Filter Assembly, 25 mm. F = fiber loading, f/mm ,
L
Q = sampling flow rate, L/min,
7.15 Triacetin (glycerol triacetate).
C = estimated concentration of SCCW, f/mL, and
e
7.16 Acetone. (Warning— Acetone is a flammable liquid
10 = conversion factor.
and requires precaution not to ignite it accidentally.)
NOTE 4—While the desired minimum loading is 100 f/mm , the
minimum loading that has statistical significance is 7 f/mm after blank
7.17 ASTM D1193 Type II Water (particle free).
correction (1).
NOTE5—Experiencehasshownthatthefiberloadingshouldnotexceed
7.18 Purity of Reagents—Reagent grade chemicals shall be
1300 f/mm (12 fibers/graticule area, average value for all counted fields)
used in all tests. Unless otherwise indicated, it is intended that
for the majority of sampling situations (1).
all reagents conform to the specifications of the Committee on
8.5.4 At a minimum, check the flow rate before and after
Analytical Reagents of theAmerican Chemical Society where
sampling. If the difference is greater than 10% from the initial
such specifications are available. Other grades may be used,
flow rate, the sample shall be rejected. Also see Test Method
provided it is first ascertained that the reagent is of sufficiently
D4532.
high purity to permit its use without lessening the accuracy of
the determination.
8.6 Carefullyremovethecassettefromthetubingattheend
of the sampling period (ensure that the cassette is positioned
8. Sample Collection
upright before interrupting the pump flow). Replace the inlet
8.1 CollectsamplesofairborneSCCWonMCEfiltersusing cap and inlet and outlet plugs, and store the cassette.
sampling cassettes and pumps in accordance with Section 7.
NOTE 6—Deactivate the sampling pump prior to disconnecting the
cassette from the tubing.
8.2 Remove the outlet plug from the sampling cassette and
connect it to a sampling pump by means of flexible,
8.7 Submit at least one field blank (or a number equal to
constriction-proof tubing.
10% of the total samples, whichever is greater) for each set of
samples. Remove the cap of the field blank briefly (approxi-
8.3 Perform a leak check of the sampling system by
mately 30 s) at the sampling site, then replace it. The field
activating the pump with the closed cassette and rotameter (or
blank is used to monitor field sampling procedures. Field
other flow measurement device) in line. Any flow indicates a
blanks shall be representative of filters used in sample collec-
leak that must be eliminated before starting the sampling
tion (for example, same filter lot number).
operation.
8.8 Submit at least one unused and unopened sealed blank
8.4 Remove the inlet plug from the sampling cassette to
which is used to monitor the supplies purchased as well as
eliminate any vacuum that may have accumulated during the
procedures used in the laboratory. The sealed blank shall be
leak test; then remove the entire inlet cap.
representativeoffiltersusedinsamplecollection(forexample,
8.5 Conduct personal and area sampling as follows:
same filter lot number).
8.5.1 For personal sampling, fasten the sampli
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